When rockets or satellites are launched into space, the entire thing doesn't usually end up there. On the way, parts are either jettisoned or they simply fall off.
According to NASA, about 500,000 such pieces of space debris are currently orbiting earth. This animation shows the 20,000 of pieces that are larger than a softball.
Story by Jacob Shamsian and editing by Stephen Parkhurst
People have been vacationing in space for 15 years.
The first non-astronaut to visit the International Space Station was businessman Dennis Tito in 2001, who paid a hefty $20 million ticket price.
But now plenty of companies have sprung up with exciting plans to bring more people to space, for fares as low as $75,000.
But that price should decrease as the space tourism industry matures into a $1 billion market by 2022.
So if you are patiently waiting for your turn to see Earth from above, these are the companies that'll take you there.
Humanity has known the Earth to be round for a few millennia and I’ve been meaning to show some of the methods of how we figured out the world is not flat.
I’ve had a few ideas on how to do that, but I got an interesting incentive, when Phil Plait (The Bad Astronomer) wrote about a recently published BBC article about “The Flat Earth” society.
Phil claims it’s ridiculous to even bother rebutting the flat earth society – and I tend to agree.
But the history of our species’ intellectual pursuit is important and interesting, and it’s very much well worth writing about. You don’t need to denounce all science and knowledge and believe in a kooky conspiracy theory to enjoy some historical factoids about humanity’s quest for space.
On we go to the top 10 ways to know the Earth is unequivocally, absolutely, positively, 100% not flat:
SEE ALSO: B.o.B thinks the earth is flat and Neil deGrasse Tyson just shut him down
CHECK OUT: QUIZ: Are these pictures of Mars or Earth?
Now that humanity knows quite positively that the Moon is not a piece of cheese or a playful god, the phenomena that accompany it (from its monthly cycles to lunar eclipses) are well-explained. It was quite a mystery to the ancient Greeks, though, and in their quest for knowledge, they came up with a few insightful observations that helped humanity figure out the shape of our planet.
Aristotle (who made quite a lot of observations about the spherical nature of the Earth) noticed that during lunar eclipses (when the Earth’s orbit places it directly between the Sun and the Moon, creating a shadow in the process), the shadow on the Moon’s surface is round. This shadow is the Earth’s, and it’s a great clue on the spherical shape of the Earth.
Since the earth is rotating (see the “Foucault Pendulum” experiment for a definite proof, if you are doubtful), the consistent oval-shadow it produces in each and every lunar eclipse proves that the earth is not only round but spherical – absolutely, utterly, beyond a shadow of a doubt not flat.
If you’ve been next to a port lately, or just strolled down a beach and stared off vacantly into the horizon, you might have, perhaps, noticed a very interesting phenomenon: approaching ships do not just “appear” out of the horizon (like they should have if the world was flat), but rather emerge from beneath the sea.
But – you say – ships do not submerge and rise up again as they approach our view (except in “Pirates of the Caribbean”, but we are hereby assuming that was a fictitious movie). The reason ships appear as if they “emerge from the waves” is because the world is not flat: it’s round.
Imagine an ant walking along the surface of an orange, into your field of view. If you look at the orange “head on”, you will see the ant’s body slowly rising up from the “horizon”, because of the curvature of the Orange. If you would do that experiment with a long road, the effect would have changed: The ant would have slowly ‘materialized’ into view, depending on how sharp your vision is.
This observation was originally made by Aristotle (384-322 BCE), who declared the Earth was round judging from the different constellations one sees while moving away from the equator.
After returning from a trip to Egypt, Aristotle noted that “there are stars seen in Egypt and […] Cyprus which are not seen in the northerly regions.” This phenomenon can only be explained with a round surface, and Aristotle continued and claimed that the sphere of the Earth is “of no great size, for otherwise the effect of so slight a change of place would not be quickly apparent.” (De caelo, 298a2-10)
The farther you go from the equator, the farther the ‘known’ constellations go towards the horizon, and are replaced by different stars. This would not have happened if the world was flat.
We may think of astronauts as robust, all-powerful supermen who can survive in the most severe conditions — even living in a tin can in the vast vacuum of space.
But they're human. And they need to eat. And ideally, their food should taste good.
Seasoning in space presents myriad challenges, though, when you're floating around in near-zero-gravity conditions. If you sprinkle some salt and pepper, it will just float away, potentially clogging air vents, contaminating their fancy equipment, or even getting painfully lodged in someone's eyeball.
To prevent this, astronauts use liquid salt and pepper, NASA astronaut Scott Kelly revealed Jan. 23 in a Reddit AMA (ask me anything).
"It would be a disaster to have something powder like that," Kelly said from the ISS, after just having passed his 300th day in space (he'll be the first American to live in space continuously for an entire year).
If a powder were to escape in the interior of the ISS, Kelly said, they would need to "consider shutting down the ventilation to stop it from spreading."
Astronauts eat three square meals per day, just like we do on Earth, including "fruits, nuts, peanut butter, chicken, beef, seafood, candy, and brownies,"according to NASA. They also drink coffee, tea, fruit juices, and lemonade.
But eating from the same bucket of freeze-dried and preserved food for weeks, months, and even years (in Kelly's case) gets old after a while.
When asked what he'd do the minute he was back on Earth, he said:
"The first thing I will eat will probably be a piece of fruit (or a cucumber) the Russian nurse hands me as soon as I am pulled out of the space capsule and begin initial health checks."
Us too, Scott Kelly. Us too.
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NOW WATCH: An astronaut played ping pong in space with a ball of water
We’ve all asked this question at some point in our lives: How long would it take to travel to the stars? Could it be within a person’s own lifetime, and could this kind of travel become the norm some day?
There are many possible answers to this question — some very simple, others in the realm of science fiction. But coming up with a comprehensive answer means taking a lot of things into consideration.
Unfortunately, any realistic assessment is likely to produce answers that would totally discourage futurists and enthusiasts of interstellar travel.
Like it or not, space is very large, and our technology is still very limited. But should we ever contemplate “leaving the nest,” we will have a range of options for getting to the nearest solar systems in our galaxy.
The nearest star to Earth is our sun, which is a fairly "average" star in the Hertzsprung-Russell Diagram's "Main Sequence." This means that it is highly stable, providing Earth with just the right type of sunlight for life to evolve on our planet.
We know there are planets orbiting other stars near to our solar system, and many of these stars are similar to our own.
In the future, should mankind wish to leave the Solar System, we’ll have a huge choice of stars we could travel to, and many could have the right conditions for life to thrive. But where would we go and how long would it take for us to get there?
Just remember: This is all speculative and there is currently no benchmark for interstellar trips. That being said, here we go!
As already noted, the closest star to our solar system is Proxima Centauri, which is why it makes the most sense to plot an interstellar mission to this system first.
As part of a triple star system called Alpha Centauri, Proxima is about 4.24 light-years (or 1.3 parsecs) from Earth.
Alpha Centauri is actually the brightest star of the three in the system — part of a closely orbiting binary 4.37 light-years from Earth — whereas Proxima Centauri (the dimmest of the three) is an isolated red dwarf about 0.13 light-years from the binary.
And while interstellar travel conjures up all kinds of visions of Faster-Than-Light (FTL) travel, ranging from warp speed and wormholes to jump drives, such theories are either highly speculative (such as the Alcubierre Drive) or entirely the province of science-fiction.
In all likelihood, any deep space mission will likely take generations to get there, rather than a few days or in an instantaneous flash.
So, starting with one of the slowest forms of space travel, how long will it take to get to Proxima Centauri?
The question of how long would it take to get somewhere in space is somewhat easier when dealing with existing technology and bodies within our solar system.
For instance, using the technology that powered the New Horizons mission — which consisted of 16 thrusters fueled with hydrazine monopropellant — reaching the Moon would take a mere 8 hours and 35 minutes.
On the other hand, there is the European Space Agency’s (ESA) SMART-1 mission, which took it’s time traveling to the moon using the method of ionic propulsion.
With this revolutionary technology, a variation of which has since been used by the Dawn spacecraft to reach Vesta, the SMART-1 mission took one year, one month and two weeks to reach the moon.
So, from the speedy rocket-propelled spacecraft to the economical ion drive, we have a few options for getting around local space — plus we could use Jupiter or Saturn for a hefty gravitational slingshot.
However, if we were to contemplate missions to somewhere a little more out of the way, we would have to scale up our technology and look at what’s really possible.
When we say possible methods, we are talking about those that involve existing technology, or those that do not yet exist, but are technically feasible.
Some, as you will see, are time-honored and proven, while others are emerging or still on the board. In just about all cases, though, they present a possible, but extremely time-consuming or expensive, scenario for getting to even the closest stars: ion propulsion.
Currently, the slowest form of propulsion, and the most fuel-efficient, is the ion engine. A few decades ago, ionic propulsion was considered to be the subject of science-fiction.
However, in recent years, the technology to support ion engines has moved from theory to practice in a big way.
The ESA’s SMART-1 mission, for example, successfully completed its mission to the moon after taking a 13 month spiral path from Earth.
SMART-1 used solar powered ion thrusters, where electrical energy was harvested from its solar panels and used to power its Hall-effect thrusters.
Only 82 kg of xenon propellant was used to propel SMART-1 to the moon. One kg of xenon propellant provided a delta-v of 45 m/s. This is a highly efficient form of propulsion, but it is by no means fast.
One of the first missions to use ion drive technology was the Deep Space 1 mission to Comet Borrelly that took place in 1998. DS1 also used a xenon-powered ion drive, consuming 81.5 kg of propellant. Over 20 months of thrusting, DS1 managed to reach a velocity of 56,000 km/hr (35,000 m/hr) during its flyby of the comet.
Ion thrusters are therefore more economical than rocket technology, as the thrust per unit mass of propellant (a.k.a. specific impulse) is far higher.
But it takes a long time for ion thrusters to accelerate spacecraft to any great speeds, and the maximum velocity it can achieve is dependent on its fuel supply and how much electrical energy it can generate.
So if ionic propulsion were to be used for a mission to Proxima Centauri, the thrusters would need a huge source of energy production (i.e., nuclear power) and a large quantity of propellant (although still less than conventional rockets).
But based on the assumption that a supply of 81.5 kg of xenon propellant translates into a maximum velocity of 56,000 km/hr (and that there are no other forms of propulsion available, such as a gravitational slingshot to accelerate it further), some calculations can be made.
In short, at a maximum velocity of 56,000 km/h, Deep Space 1 would take over 81,000 years to traverse the 4.24 light-years between Earth and Proxima Centauri.
To put that time-scale into perspective, that would be over 2,700 human generations. So it is safe to say that an interplanetary ion engine mission would be far too slow to be considered for a manned interstellar mission.
But, should ion thrusters be made larger and more powerful (i.e., ion exhaust velocity would need to be significantly higher), and enough propellant could be hauled to keep the spacecraft going for the entire 4.243 light-year trip, that travel time could be greatly reduced. Still not enough to happen in someone’s lifetime, though.
The fastest existing means of space travel is known as the gravity assist method, which involves a spacecraft using the relative movement (i.e., orbit) and gravity of a planet to alter is path and speed. Gravitational assists are a very useful spaceflight technique, especially when using the Earth or another massive planet (like a gas giant) for a boost in velocity.
The Mariner 10 spacecraft was the first to use this method, using Venus’ gravitational pull to slingshot it toward Mercury in February 1974.
In the 1980s, the Voyager 1 probe used Saturn and Jupiter for gravitational slingshots to attain its current velocity of 60,000 km/hr (38,000 m/hr) and make it into interstellar space.
However, it was the Helios 2 mission — which was launched in 1976 to study the interplanetary medium from 0.3 AU to 1 AU to the sun — that holds the record for highest speed achieved with a gravity assist.
At the time, Helios 1 (which launched in 1974) and Helios 2 held the record for closest approach to the Sun. Helios 2 was launched by a conventional NASA Titan/Centaur launch vehicle and placed in a highly elliptical orbit.
Due to the large eccentricity (0.54) of the 190 day solar orbit, at perihelion Helios 2 was able to reach a maximum velocity of over 240,000 km/hr (150,000 m/hr). This orbital speed was attained by the gravitational pull of the sun alone.
Technically, the Helios 2 perihelion velocity was not a gravitational slingshot, it was a maximum orbital velocity, but it still holds the record for being the fastest man-made object regardless.
So, if Voyager 1 was traveling in the direction of the red dwarf Proxima Centauri at a constant velocity of 60,000 km/hr, it would take 76,000 years (or over 2,500 generations) to travel that distance.
But if it could attain the record-breaking speed of Helios 2's close approach of the sun — a constant speed of 240,000 km/hr — it would take 19,000 years (or over 600 generations) to travel 4.243 light years. Significantly better, but still not in the ream of practicality.
Another proposed method of interstellar travel comes in the form of the Radio Frequency (RF) Resonant Cavity Thruster, also known as the EM drive.
Originally proposed in 2001 by Roger K. Shawyer, a UK scientist who started Satellite Propulsion Research Ltd (SPR) to bring it to fruition, this drive is built around the idea that electromagnetic microwave cavities can allow for the direct conversion of electrical energy to thrust.
Whereas conventional electromagnetic thrusters are designed to propel a certain type of mass (such as ionized particles), this particular drive system relies on no reaction mass and emits no directional radiation.
Such a proposal has met with a great deal of skepticism, mainly because it violates the law of Conservation of Momentum — which states that within a system, the amount of momentum remains constant and is neither created nor destroyed, but only changes through the action of forces.
However, recent experiments with the technology have apparently yielded positive results. In July 2014, at the 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference in Cleveland, Ohio, researchers from NASA’s advanced propulsion research claimed that they had successfully tested a new design for an electromagnetic propulsion drive.
This was followed up in April 2015 when researchers at NASA Eagleworks (part of the Johnson Space Center) claimed that they had successfully tested the drive in a vacuum, an indication that it might actually work in space.
In July of that same year, a research team from the Dresden University of Technology’s Space System department built their own version of the engine and observed a detectable thrust.
And in 2010, Prof. Juan Yang of the Northwestern Polytechnical University in Xi’an, China, began publishing a series of papers about her research into EM drive technology.
This culminated in her 2012 paper where she reported higher input power (2.5 kW) and tested thrust (720 mN) levels. In 2014, she further reported extensive tests involving internal temperature measurements with embedded thermocouples, which seemed to confirm that the system worked.
According to calculations based on the NASA prototype (which yielded a power estimate of 0.4 N/kilowatt), a spacecraft equipped with the EM drive could make the trip to Pluto in less than 18 months. That’s one-sixth the time it took for the New Horizons probe to get there, which was traveling at speeds of close to 58,000 km/h (36,000 m/hr).
Sounds impressive. But even at that rate, it would take a ship equipped with EM engines over 13,000 years for the vessel to make it to Proxima Centauri. Getting closer, but not quickly enough, and until such time that technology can be definitively proven to work, it doesn’t make much sense to put our eggs into this basket.
Another possibility for interstellar space flight is to use spacecraft equipped with nuclear engines, a concept which NASA has been exploring for decades.
In a nuclear thermal propulsion (NTP) rocket, uranium or deuterium reactions are used to heat liquid hydrogen inside a reactor, turning it into ionized hydrogen gas (plasma), which is then channeled through a rocket nozzle to generate thrust.
A nuclear electric propulsion (NEP) rocket involves the same basic reactor converting its heat and energy into electrical energy, which would then power an electrical engine.
In both cases, the rocket would rely on the nuclear fission of fusion to generate propulsion rather than chemical propellants, which has been the mainstay of NASA and all other space agencies to date.
Compared to chemical propulsion, both NTP and NEP offer a number of advantages. The first and most obvious is the virtually unlimited energy density compared to rocket fuel.
In addition, a nuclear-powered engine could also provide superior thrust relative to the amount of propellant used. This would cut the total amount of propellant needed, thus cutting launch weight and the cost of individual missions.
Although no nuclear-thermal engines have ever flown, several design concepts have been built and tested over the past few decades, and numerous concepts have been proposed.
These have ranged from the traditional solid-core design — such as the Nuclear Engine for Rocket Vehicle Application (NERVA) — to more advanced and efficient concepts that rely on either a liquid or a gas core.
However, despite these advantages in fuel-efficiency and specific impulse, the most sophisticated NTP concept has a maximum specific impulse of 5,000 seconds (50 kN·s/kg).
Using nuclear engines driven by fission or fusion, NASA scientists estimate it would could take a spaceship only 90 days to get to Mars when the planet was at “opposition” — i.e., as close as 55 million km from Earth.
But adjusted for a one-way journey to Proxima Centauri, a nuclear rocket would still take centuries to accelerate to the point where it was flying a fraction of the speed of light.
It would then require several decades of travel time, followed by many more centuries of deceleration before reaching it destination. All told, we're still talking about 1,000 years before it reaches its destination. Good for interplanetary missions, not so good for interstellar ones.
Using existing technology, the time it would take to send scientists and astronauts on an interstellar mission would be prohibitively slow.
If we want to make that journey within a single lifetime, or even a generation, something a bit more radical (a.k.a. highly theoretical) will be needed.
And while wormholes and jump engines may still be pure fiction at this point, there are some rather advanced ideas that have been considered over the years.
Nuclear pulse propulsion is a theoretically possible form of fast space travel.
The concept was originally proposed in 1946 by Stanislaw Ulam, a Polish-American mathematician who participated in the Manhattan Project, and preliminary calculations were then made by F. Reines and Ulam in 1947.
The actual project — known as Project Orion — was initiated in 1958 and lasted until 1963.
Led by Ted Taylor at General Atomics and physicist Freeman Dyson from the Institute for Advanced Study in Princeton, Orion hoped to harness the power of pulsed nuclear explosions to provide a huge thrust with very high specific impulse (i.e., the amount of thrust compared to weight or the amount of seconds the rocket can continually fire).
In a nutshell, the Orion design involves a large spacecraft with a high supply of thermonuclear warheads achieving propulsion by releasing a bomb behind it and then riding the detonation wave with the help of a rear-mounted pad called a “pusher.”
After each blast, the explosive force would be absorbed by this pusher pad, which then translates the thrust into forward momentum.
Though hardly elegant by modern standards, the advantage of the design is that it achieves a high specific impulse — meaning it extracts the maximum amount of energy from its fuel source (in this case, nuclear bombs) at minimal cost.
In addition, the concept could theoretically achieve very high speeds, with some estimates suggesting a ballpark figure as high as 5% the speed of light (or 5.4×107 km/hr).
But of course, there the inevitable downsides to the design. For one, a ship of this size would be incredibly expensive to build.
According to estimates produced by Dyson in 1968, an Orion spacecraft that used hydrogen bombs to generate propulsion would weight 400,000 to 4 million metric tons. And at least three-quarters of that weight consists of nuclear bombs, where each warhead weights approximately 1 metric ton.
All told, Dyson’s most conservative estimates placed the total cost of building an Orion craft at $367 billion.
Adjusted for inflation, that works out to roughly $2.5 trillion — which accounts for over two-thirds of the US government’s current annual revenue. Hence, even at its lightest, the craft would be extremely expensive to manufacture.
There’s also the slight problem of all the radiation it generates, not to mention nuclear waste. In fact, it is for this reason that the project is believed to have been terminated, owing to the passage of the Partial Test Ban Treaty of 1963, which sought to limit nuclear testing and stop the excessive release of nuclear fallout into the planet’s atmosphere.
Another possibility within the realm of harnessed nuclear power involves rockets that rely on thermonuclear reactions to generate thrust.
For this concept, energy is created when pellets of a deuterium/helium-3 mix are ignited in a reaction chamber by inertial confinement using electron beams (similar to what is done at the National Ignition Facility in California).
This fusion reactor would detonate 250 pellets per second to create high-energy plasma, which would then be directed by a magnetic nozzle to create thrust.
Like a rocket that relies on a nuclear reactor, this concept offers advantages as far as fuel efficiency and specific impulse are concerned. Exhaust velocities of up to 10,600 km/s are estimated, which is far beyond the speed of conventional rockets.
What’s more, the technology has been studied extensively over the past few decades, and many proposals have been made.
For example, between 1973 and 1978, the British Interplanetary Society conducted a feasibility study known as Project Daedalus. Relying on current knowledge of fusion technology and existing methods, the study called for the creation of a two-stage unmanned scientific probe making a trip to Barnard’s Star (5.9 light-years from Earth) in a single lifetime.
The first stage, the larger of the two, would operate for 2.05 years and accelerate the spacecraft to 7.1% the speed of light (o.071 c). This stage would then be jettisoned, at which point the second stage would ignite its engine and accelerate the spacecraft up to about 12% of light speed (0.12 c) over the course of 1.8 years.
The second-stage engine would then be shut down and the ship would enter into a 46-year cruise period.
According to the Project’s estimates, the mission would take 50 years to reach Barnard’s Star. Adjusted for Proxima Centauri, the same craft could make the trip in 36 years.
But of course, the project also identified numerous stumbling blocks that made it unfeasible using then-current technology — most of which are still unresolved.
For instance, there is the fact that helium-3 is scare on Earth, which means it would have to be mined elsewhere (most likely on the moon). Second, the reaction that drives the spacecraft requires that the energy released vastly exceed the energy used to trigger the reaction.
And while experiments here on Earth have surpassed the “break-even goal,” we are still a long way away from the kinds of energy needed to power an interstellar spaceship.
Third, there is the cost factor of constructing such a ship. Even by the modest standard of Project Daedalus’ unmanned craft, a fully fueled craft would weigh as much as 60,000 Mt. To put that in perspective, the gross weight of NASA’s SLS is just over 30 Mt, and a single launch comes with a price tag of $5 billion (based on estimates made in 2013).
In short, a fusion rocket would not only be prohibitively expensive to build, but it would require a level of fusion reactor technology that is currently beyond our means.
Icarus Interstellar, an international organization of volunteer citizen scientists (some of whom worked for NASA or the ESA) have since attempted to revitalize the concept with Project Icarus. Founded in 2009, the group hopes to make fusion propulsion (among other things) feasible by the near future.
Also known as the Bussard Ramjet, this theoretical form of propulsion was first proposed by physicist Robert W. Bussard in 1960.
Basically, it is an improvement over the standard nuclear fusion rocket, which uses magnetic fields to compress hydrogen fuel to the point that fusion occurs. But in the Ramjet’s case, an enormous electromagnetic funnel “scoops” hydrogen from the interstellar medium and dumps it into the reactor as fuel.
As the ship picks up speed, the reactive mass is forced into a progressively constricted magnetic field, compressing it until thermonuclear fusion occurs.
The magnetic field then directs the energy as rocket exhaust through an engine nozzle, thereby accelerating the vessel. Without any fuel tanks to weigh it down, a fusion ramjet could achieve speeds approaching 4% of the speed of light and travel anywhere in the galaxy.
However, the potential drawbacks of this design are numerous. For instance, there is the problem of drag. The ship relies on increased speed to accumulate fuel, but as it collides with more and more interstellar hydrogen, it may also lose speed — especially in denser regions of the galaxy.
Second, deuterium and tritium (used in fusion reactors here on Earth) are rare in space, whereas fusing regular hydrogen (which is plentiful in space) is beyond our current methods.
This concept has been popularized extensively in science-fiction. Perhaps the best known example of this is in the franchise of Star Trek, where “Bussard collectors” are the glowing nacelles on warp engines.
But in reality, our knowledge of fusion reactions need to progress considerably before a ramjet is possible. We would also have to figure out that pesky drag problem before we began to consider building such a ship!
Solar sails have long been considered to be a cost-effective way of exploring the solar system. In addition to being relatively easy and cheap to manufacture, there’s the added bonus of solar sails requiring no fuel.
Rather than using rockets that require propellant, the sail uses the radiation pressure from stars to push large ultra-thin mirrors to high speeds.
However, for the sake of interstellar flight, such a sail would need to be driven by focused energy beams (i.e. lasers or microwaves) to push it to a velocity approaching the speed of light.
The concept was originally proposed by Robert Forward in 1984, who was a physicist at Hughes Aircraft’s research laboratories at the time.
The concept retains the benefits of a solar sail, in that it requires no onboard fuel, but also from the fact that laser energy does not dissipate with distance nearly as much as solar radiation. So while a laser-driven sail would take some time to accelerate to near-luminous speeds, it would be limited only to the speed of light itself.
According to a 2000 study produced by Robert Frisbee, a director of advanced propulsion concept studies at NASA’s Jet Propulsion Laboratory, a laser sail could be accelerated to half the speed of light in less than a decade.
He also calculated that a sail measuring about 320 km (200 miles) in diameter could reach Proxima Centauri in just over 12 years. Meanwhile, a sail measuring about 965 km (600 miles) in diameter would arrive in just under 9 years.
However, such a sail would have to be built from advanced composites to avoid melting. Combined with its size, this would add up to a pretty penny!
Even worse is the sheer expense incurred from building a laser large and powerful enough to drive a sail to half the speed of light. According to Frisbee’s own study, the lasers would require a steady flow of 17,000 terawatts of power — close to what the entire world consumes in a single day.
Fans of science-fiction are sure to have heard of antimatter. But in case you haven’t, antimatter is essentially material composed of antiparticles, which have the same mass but opposite charge as regular particles.
An antimatter engine, meanwhile, is a form of propulsion that uses interactions between matter and antimatter to generate power, or to create thrust.
In short, an antimatter engine involves particles of hydrogen and antihydrogen being slammed together. This reaction unleashes as much energy as a thermonuclear bomb, along with a shower of subatomic particles called pions and muons. These particles, which would travel at one-third the speed of light, are then channeled by a magnetic nozzle to generate thrust.
The advantage to this class of rocket is that a large fraction of the rest mass of a matter/antimatter mixture may be converted to energy, allowing antimatter rockets to have a far higher energy density and specific impulse than any other proposed class of rocket.
What’s more, controlling this kind of reaction could conceivably push a rocket up to half the speed of light.
Pound for pound, this class of ship would be the fastest and most fuel-efficient ever conceived. Whereas conventional rockets require tons of chemical fuel to propel a spaceship to its destination, an antimatter engine could do the same job with just a few milligrams of fuel.
In fact, the mutual annihilation of a half pound of hydrogen and antihydrogen particles would unleash more energy than a 10-megaton hydrogen bomb.
It is for this exact reason that NASA’s Institute for Advanced Concepts (NIAC) has investigated the technology as a possible means for future Mars missions.
Unfortunately, when contemplating missions to nearby star systems, the amount of fuel it needs to make the trip is multiplied exponentially, and the cost involved in producing it would be astronomical (no pun).
According to report prepared for the 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit (also by Robert Frisbee), a two-stage antimatter rocket would need over 815,000 metric tons (900,000 US tons) of fuel to make the journey to Proxima Centauri in approximately 40 years. That’s not bad, as far as timelines go. But again, the cost ...
Whereas a single gram of antimatter would produce an incredible amount of energy, it is estimated that producing just 1 gram would require approximately 25 million billion kilowatt-hours of energy and cost over a trillion dollars. At present, the total amount of antimatter that has been created by humans is less 20 nanograms.
And even if we could produce antimatter for cheap, you would need a massive ship to hold the amount of fuel needed. According to a report by Dr. Darrel Smith and Jonathan Webby of the Embry-Riddle Aeronautical University in Arizona, an interstellar craft equipped with an antimatter engine could reach 0.5 the speed of light and reach Proxima Centauri in a little over 8 years.
However, the ship itself would weigh 400 Mt, and would need 170 Mt of antimatter fuel to make the journey.
A possible way around this is to create a vessel that can create antimatter, which it could then store as fuel. This concept, known as the Vacuum to Antimatter Rocket Interstellar Explorer System (VARIES), was proposed by Richard Obousy of Icarus Interstellar.
Based on the idea of in-situ refueling, a VARIES ship would rely on large lasers (powered by enormous solar arrays) which would create particles of antimatter when fired at empty space.
Much like the Ramjet concept, this proposal solves the problem of carrying fuel by harnessing it from space. But once again, the sheer cost of such a ship would be prohibitively expensive using current technology. In addition, the ability to create dark matter in large volumes is not something we currently have the power to do.
There’s also the matter of radiation, as matter-antimatter annihilation can produce blasts of high-energy gamma rays.
This not only presents a danger to the crew, requiring significant radiation shielding, but requires the engines be shielded as well to ensure that they don’t undergo atomic degradation from all the radiation they are exposed to.
So bottom line, the antimatter engine is completely impractical with our current technology and in the current budget environment.
Fans of science-fiction are also no doubt familiar with the concept of an Alcubierre (or “warp”) drive.
Proposed by Mexican physicist Miguel Alcubierre in 1994, this method was an attempt to make FTL travel possible without violating Einstein’s theory of special relativity.
In short, the concept involves stretching the fabric of space-time in a wave, which would theoretically cause the space ahead of an object to contract and the space behind it to expand.
An object inside this wave (i.e., a spaceship) would then be able to ride this wave, known as a “warp bubble,” beyond relativistic speeds.
Since the ship is not moving within this bubble but is being carried along as it moves, the rules of space-time and relativity would cease to apply. The reason being is that this method does not rely on moving faster than light in the local sense.
It is only “faster than light” in the sense that the ship could reach its destination faster than a beam of light that was traveling outside the warp bubble.
So assuming that a spacecraft could be outfitted with an Alcubierre drive system, it would be able to make the trip to Proxima Centauri in less than 4 years. So when it comes to theoretical interstellar space travel, this is by far the most promising technology, at least in terms of speed.
Naturally, the concept has received its share of counter-arguments over the years. Chief among them are the fact that it does not take quantum mechanics into account, and could be invalidated by a Theory of Everything (such as loop quantum gravity).
Calculations on the amount of energy required have also indicated that a warp drive would require a prohibitive amount of power to work. Other uncertainties include the safety of such a system, the effects on space-time at the destination, and violations of causality.
However, in 2012, NASA scientist Harold Sonny White announced that he and his colleagues had begun researching the possibility of an Alcubierre Drive.
In a paper titled "Warp Field Mechanics 101," White claimed that they had constructed an interferometer that will detect the spatial distortions produced by the expanding and contracting of space-time of the Alcubierre metric.
In 2013, the Jet Propulsion Laboratory published results of a warp field test which was conducted under vacuum conditions. Unfortunately, the results were reported as “inconclusive.”
Long term, we may find that Alcubierre’s metric may violate one or more fundamental laws of nature. And even if the physics should prove to be sound, there is no guarantee it can be harnessed for the sake of FTL flight.
In conclusion, if you were hoping to travel to the nearest star within your lifetime, the outlook isn’t very good. However, if mankind felt the incentive to build an “interstellar ark” filled with a self-sustaining community of space-faring humans, it might be possible to travel there in a little under a century if we were willing to invest in the requisite technology.
But all the available methods are still very limited when it comes to transit time. And while taking hundreds or thousands of years to reach the nearest star may matter less to us if our very survival was at stake, it is simply not practical as far as space exploration and travel goes.
By the time a mission reached even the closest stars in our galaxy, the technology employed would be obsolete and humanity might not even exist back home anymore.
So unless we make a major breakthrough in the realms of fusion, antimatter, or laser technology, we will either have to be content with exploring our own solar system, or be forced to accept a very long-term transit stratagem ...
We have written many interesting articles about space travel here at Universe Today. Here’s Will We Ever Reach Another Star?, Warp Drives May Come With a Killer Downside, The Alcubierre Warp Drive, How Far Is a Light Year?, When Light Just Isn’t Fast Enough, When Will We Become Interstellar?, and Can We Travel Faster Than the Speed of Light?
For more information, be sure to consult NASA’s pages on Propulsion Systems of the Future, and Is Warp Drive Real?
And fans of interstellar travel should definitely check out Icarus Interstellar and the Tau Zero Foundation websites. Keep reaching for those stars!
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The chairman of the Senate Armed Services Committee is assailing the Defense Department for relying on Russian rocket engines to launch American military satellites into space.
At a committee hearing Wednesday, Republican John McCain of Arizona says Russia holds many of the United States' "most precious national security satellites at risk before they ever get off the ground."
Yet McCain says the department has actively sought to undermine the committee's direction to limit the risk and stop the use of the Russian RD-180 engines by the end of this decade.
Air Force Secretary Deborah James says the department is working to end the use of the Russian engines as soon as possible.
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Scott Kelly is a cool guy. In addition to being, you know, an astronaut, he's also the first American to live in space continuously for an entire year. He just surpassed his 300th day up there.
He also looks pretty unflappable in this photo, with those crossed arms and that stern grin. In fact, many astronauts take photos like that.
But that posture isn't just for the sake of exuding vigor and resilience — it actually serves an important purpose, Kelly revealed January 23 in a Reddit AMA (ask me anything).
"Your arms don't hang by your side in space like they do on Earth because there is no gravity," Kelly said in response to user Doug_Lee's question about the deal with astronauts and folded arms.
"It feels awkward to have them floating in front of me. It is just more comfortable to have them folded," Kelly wrote (or rather, someone at NASA wrote for him as he spoke from space).
It's a simple solution to a complicated problem. Who wants to walk around the space station looking like Frankenstein?
Kelly even assumes this arm posture when he's getting some shuteye: "I don't even have them floating in my sleep," he said during the AMA. "I put them in my sleeping bag."
It's a great example of the many adjustments astronauts must make when living in the near zero gravity conditions, including the way they season their food, keep track of time, cry, and use the bathroom.
Something to think about when you're getting all brash with your gravity and your normal-hanging arms on Earth.
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When President Ronald Reagan heard about the Challenger explosion the morning of January 28, 1986, he was preparing to give the State of the Union address that very night.
He postponed the speech for the following week, and instead directly addressed the nation on the disaster.
His words were mournful, but also inspirational, promising that this bleak event would not be the last of America's exploration into space — but rather a painful "part of the process" of expanding humankind's horizons.
"We'll continue our quest in space," Reagan said from the Oval Office that evening. "There will be more shuttle flights and more shuttle crews and, yes, more volunteers, more civilians, more teachers in space. Nothing ends here; our hopes and our journeys continue."
The Challenger disaster was the worst tragedy in US spaceflight history, taking the lives of the seven crewmembers onboard, including civilian high school teacher and trained payload specialist Christa McAuliffe.
McAuliffe is the second woman you see here, in the last footage before the crew boarded the Challenger spacecraft:
Reagan also addressed schoolchildren who watched the launch live on TV in order to see McAuliffe, the first teacher bound for space, make her historic flight:
"I know it is hard to understand, but sometimes painful things like this happen," he said. "It's all part of the process of exploration and discovery. It's all part of taking a chance and expanding man's horizons. The future doesn't belong to the fainthearted; it belongs to the brave. The Challenger crew was pulling us into the future, and we'll continue to follow them."
As the US transitions into a predominantly private space program, with companies like SpaceX, Orbital ATK, and Blue Origin pushing to ever greater heights, Reagan's words are just as poignant today. They also ring true for the rising space tourism industry and Virgin Galactic's deadly SpaceShipTwo crash in October 2014.
We've posted the full text of his speech after this video from the Ronald Reagan Presidential Library, which shows the entire address:
And here's the speech in its entirety, from NASA's archives:
Ladies and gentlemen, I'd planned to speak to you tonight to report on the state of the Union, but the events of earlier today have led me to change those plans. Today is a day for mourning and remembering.
Nancy and I are pained to the core by the tragedy of the shuttle Challenger. We know we share this pain with all of the people of our country. This is truly a national loss.
Nineteen years ago, almost to the day, we lost three astronauts in a terrible accident on the ground. But we've never lost an astronaut in flight; we've never had a tragedy like this. And perhaps we've forgotten the courage it took for the crew of the shuttle; but they, the Challenger Seven, were aware of the dangers, but overcame them and did their jobs brilliantly. We mourn seven heroes: Michael Smith, Dick Scobee, Judith Resnik, Ronald McNair, Ellison Onizuka, Gregory Jarvis, and Christa McAuliffe. We mourn their loss as a nation together.
For the families of the seven, we cannot bear, as you do, the full impact of this tragedy. But we feel the loss, and we're thinking about you so very much. Your loved ones were daring and brave, and they had that special grace, that special spirit that says, "Give me a challenge and I'll meet it with joy." They had a hunger to explore the universe and discover its truths. They wished to serve, and they did. They served all of us.
We've grown used to wonders in this century. It's hard to dazzle us. But for 25 years the United States space program has been doing just that. We've grown used to the idea of space, and perhaps we forget that we've only just begun. We're still pioneers. They, the members of the Challenger crew, were pioneers.
And I want to say something to the schoolchildren of America who were watching the live coverage of the shuttle's takeoff. I know it is hard to understand, but sometimes painful things like this happen. It's all part of the process of exploration and discovery. It's all part of taking a chance and expanding man's horizons. The future doesn't belong to the fainthearted; it belongs to the brave. The Challenger crew was pulling us into the future, and we'll continue to follow them.
I've always had great faith in and respect for our space program, and what happened today does nothing to diminish it. We don't hide our space program. We don't keep secrets and cover things up. We do it all up front and in public. That's the way freedom is, and we wouldn't change it for a minute.
We'll continue our quest in space. There will be more shuttle flights and more shuttle crews and, yes, more volunteers, more civilians, more teachers in space. Nothing ends here; our hopes and our journeys continue.
I want to add that I wish I could talk to every man and woman who works for NASA or who worked on this mission and tell them: "Your dedication and professionalism have moved and impressed us for decades. And we know of your anguish. We share it."
There's a coincidence today. On this day 390 years ago, the great explorer Sir Francis Drake died aboard ship off the coast of Panama. In his lifetime the great frontiers were the oceans, and an historian later said, "He lived by the sea, died on it, and was buried in it." Well, today we can say of the Challenger crew: Their dedication was, like Drake's, complete.
The crew of the space shuttle Challenger honored us by the manner in which they lived their lives. We will never forget them, nor the last time we saw them, this morning, as they prepared for their journey and waved goodbye and "slipped the surly bonds of earth" to "touch the face of God."
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On Monday, the space agencies of India and France signed a letter of intent stating that the two will collaborate on India's next mission to Mars, SpaceNews reported.
This mission, which is scheduled to launch in 2020 and would involve sending a satellite into orbit around the Red Planet, will mark India's second mission to Mars in history.
While the 2020 orbiter will not set a lander on Mars' surface, the president of French space agency National Centre for Space Studies (CNES) Jean-Yves Le Gall said a lander mission might not be far off for India.
"After India's Mars orbiter, the next step has to be a lander. A lander on Mars is not easy, but it will be interesting to undertake," Le Gall told NDTV.
When Le Gall says that sending a lander to Mars "is not easy," he's not kidding.
In the history of deep space exploration, only three space agencies have attempted a Mars lander: the Soviet Space Program, NASA, and the European Space Agency (ESA).
Of those three, NASA is the only agency who's had landers that functioned for longer than 15 seconds after touchdown. In fact, NASA's latest lander, the Opportunity rover, just celebrated 12 years of exploration on the surface.
Needless to say, sending a lander to Mars is a major undertaking. But with a partner like CNES, India might just pull it off.
Founded in 1961, CNES has helped design and build the technology for such groundbreaking missions as ESA's Rosetta mission to comet 67P/Churyumov-Gerasimenko and its Philae lander as well as the Cassini-Huygens mission, which included an atmospheric probe — Huygens — that landed on Saturn's moon, Titan.
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NOW WATCH: Scientists can't explain these mysterious spots on one of Saturn's most remarkable moons
Scientists used to suspect a giant planet named "2MASS J2126-8140" was a rogue world, wandering the galaxy without a star to orbit. But it turns out the planet isn't homeless after all: its star is just very, very far away. Like, a trillion kilometers away (or about 621,000,000,000 miles).
To put that number into context, that's around 6,900 times the distance between the Sun and Earth. Its orbit is 140 times wider than Pluto's. At that distance, the dim red dwarf star would look like just another moderately bright star in the sky.
Astronomer Simon Murphy from the Australian National University and his colleagues uncovered the secret relationship between the planet and star after noticing that they were both located 100 light-years from Earth. Further analysis showed they were moving together as well.
The planet is believed to be a gas giant 12 to 15 times the size of Jupiter, and takes nearly a million Earth years to circle its star.
Scientists aren't sure how such a far-flung solar system could have formed. “There is no way it formed in the same way as our solar system did, from a large disc of dust and gas,” Murphy said in a press statement.
Instead, the team suspects the star-planet duo were born relatively recently (10 to 45 million years ago, compared to our solar system's birth 4.5 billion years ago), and that they formed from “a filament of gas that pushed them together in the same direction," says Murphy.
"They must not have lived their lives in a very dense environment. They are so tenuously bound together that any nearby star would have disrupted their orbit completely.”
This article originally appeared on Popular Science.
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It was one of those moments you’ll never forget.
Thirty years ago, the Challenger space shuttle exploded 73 seconds after launch.
In an instant, a dream became a tragedy – and all because a small, simple seal had failed in the right solid rocket booster.
I remember the event well. I had a dark cubbyhole of an office overlooking a doorway that was a short-cut between our offices and the bar, where there was a television.
At just after five o’clock, when I was thinking of packing up for the day, a colleague banged on my window. “The shuttle has exploded,” he said. “We’re going to see if there’s any news on TV”.
He had heard a news bulletin on his radio and wanted to find out what had happened. It’s all too easy to forget now that in those days you couldn’t just do a quick internet search or flick over to the news channel. The news was broadcast at specific times – and the BBC evening news was not on until 6pm.
I saw the first film footage of the disaster on the children’s news programme, Newsround– appropriate since the mission was the first to have a teacher, Christa McAuliffe, on board, and Newsround had been following the build-up to the launch.
Like millions of others, I hoped that the appearance of several streaks from the shuttle signified that the seven-strong crew had escaped and would soon be rescued from the Atlantic Ocean. But, as is well-known, that was not the case – and the subsequent Rogers Commission found that Sharon Christa McAuliffe, Gregory Jarvis, Judith A. Resnik, Francis R. (Dick) Scobee, Ronald E. McNair, Mike J. Smith and Ellison S. Onizuka were likely to have either died from hypoxia during their return through the atmosphere, or on impact with the water surface. They were the first American astronauts to die in flight.
Since then, there have been advances in communication that have changed the world almost beyond recognition. We no longer have to wait for a news bulletin to receive information, or go to a specific location to watch footage of an event. We carry the news with us – mobile phones and social media give 24/7 access to world events, relaying images and commentary from one side of the globe to the other almost instantly. But has space travel changed that much?
That Challenger mission was the 25th to take off as part of the main Shuttle Transportation System (STS) program. Its launch came at a time when almost every launch was a mission “first”, whether it featured the first American woman, the first African-American, the first European, the first politician. Interest in STS-51-L was particularly high, because school students had followed selection of Christa McAuliffe from 11,000 applicants as part of the Teacher in Space Project. US president Ronald Reagan’s subsequent speech – paraphrasing John Gillespie Magee’s poem High Flight– expressed the enormity of the calamity.
We will never forget them, nor the last time we saw them, this morning, as they prepared for their journey and waved goodbye and ‘slipped the surly bonds of earth’ to ‘touch the face of God’.
The shuttle program was suspended for almost three years and, following its re-introduction, flew 88 successful missions in 14 years, most of which were to build and supply the International Space Station (ISS). The Columbia disaster of February 2003, when the shuttle disintegrated on re-entry, killing all seven crew, again halted the program. One of the most damning findings of the Columbia Accident Investigation Board was the criticism of NASA’s decision-making, its risk assessment procedures and its organizational structures – concluding that NASA had failed to learn many of the lessons from Challenger.
The shuttle program ended in 2011, at first leaving supply of the ISS dependent on the Russian Soyuz and European Ariane rockets. Latterly, the private companies SpaceX and Orbital Sciences have also been contracted to transport cargo to and from the ISS.
So what is the legacy of Challenger? Have we taken on board all the advanced safety requirements that followed the two shuttle disasters? Have the recommendations on organizational change been followed? Sadly, until there is another disaster, we probably won’t know. But with every successful launch that takes place, we can be more certain that spaceflight – at least unmanned spaceflight – is becoming more routine.
On the other hand, human spaceflight as a regular, accepted mode of travel is seemingly as far away as it was in 1986. The arrival of private companies on the scene has given more impetus to the idea that space travel for pleasure is achievable – but the crash of Virgin Galactic’s SpaceShip Two in November 2014 again questioned the safety of such enterprises.
There is a Global Space Exploration Programme and NASA has reaffirmed its commitment to human exploration of Mars. Meanwhile, ESA’s director-general, Johann-Dietrich Woerner, has declared that he wants to build a village on the Moon, probably using 3D printer technology, and that it should be a global village for all nations. But the truth is that many of the documents associated with these ventures are aspirational rather than realistic.
Future visions of human space exploration are either inspiring or laughable, depending where you sit on the optimism-pessimism scale. But they do give us something to strive for – and surely that is the best lesson to take from Challenger, and a fitting tribute to those who have lost their lives in space. Never give up, we’ll get there in the end. And the views will be breathtaking.
Monica Grady, Professor of Planetary and Space Sciences, The Open University
This article was originally published on The Conversation. Read the original article.
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Big Bird could have been on the Challenger space shuttle when it exploded on January, 28 1986.
One of the reasons why he wasn't? His costume was too big.
Caroll Spinney has played the beloved Sesame Street character since the beginning, and he told the story of his brush with spaceflight in "I Am Big Bird," a documentary about his life as the character, released last year.
"I once got a letter from NASA, asking if I would be willing to join a mission to orbit the Earth as Big Bird, to encourage kids to get interested in space," Spinney said in an essay in The Guardian. "There wasn't enough room for the puppet in the end, and I was replaced by a teacher."
Big Bird's costume is more than eight feet tall, and it was simply too big to fit on the Challenger shuttle. Tragically, high school teacher and trained payload specialist Christa McAuliffe took his place, and died along with the six other crewmembers aboard the shuttle that day.
NBC News reported that NASA confirmed sending Sesame Street characters into space was a consideration, but never more than that.
"In 1984, NASA created the Space Flight Participant Program to select teachers, journalists, artists, and other people who could bring their unique perspective to the human spaceflight experience as a passenger on the space shuttle,"NASA said in the statement. "A review of past documentation shows there were initial conversations with Sesame Street regarding their potential participation on a Challenger flight, but that plan was never approved."
Though Spinney didn't go into space as Big Bird, he still felt a special connection to the Challenger the day it exploded.
"We were taping another episode of Sesame Street at the time it went up and they said, 'The ship is about to take off so we’re going to punch the broadcast of the takeoff onto the monitors on the set,'"Spinney told CDC News. "So we stopped working and watched the monitors and when we saw it blow up, it was like my scalp crawled."
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The morning of January 28, 1986 was cold. So cold that icicles formed a freezing ring around the space shuttle Challenger's launch pad at the Kennedy Space Center in Cape Canaveral, Florida.
After some delays, Challenger launched at 11:38 a.m. But 73 seconds into the flight, as family members and onlookers watched from below, the unimaginable happened: The space shuttle exploded, killing all seven astronauts aboard.
The people aboard included Christa McAuliffe, a schoolteacher from New Hampshire who was the first civilian in space.
While tragic, the Challenger disaster ultimately changed the way humans interacted with the final frontier in some strikingly positive ways. Buried within former President Ronald Reagan's immediate response to the disaster was this inspiring quote:
I know it is hard to understand, but sometimes painful things like this happen. It's all part of the process of exploration and discovery. It's all part of taking a chance and expanding man's horizons. The future doesn't belong to the fainthearted; it belongs to the brave.
We'll continue our quest in space. There will be more shuttle flights and more shuttle crews and, yes, more volunteers, more civilians, more teachers in space. Nothing ends here; our hopes and our journeys continue.
Just like that, hours after one of the largest disasters in American space-faring history, Reagan called for "more civilians in space." And this was a long time coming.
Back in 1983, George Keyworth, Reagan's top science advisor, penned an essay elaborating on the administration's plans to open up space travel to private citizens, as well as companies.
"Like an evolving company, the US space program has options for both horizontal and vertical expansion," Keyworth writes, per the Huffington Post. "I would characterize the evolution of commercial launch services as a kind of vertical expansion."
And it was the dramatic end of the Challenger that sowed the seeds of the private space race.
A multi-agency investigation into the disaster ultimately concluded that faulty O-rings (and NASA technicians not accounting for the cold) — which, when frozen, allowed ignition gases to spark the fuel tanks — caused the explosion, reports Motherboard.
The investigation also found more systemic problems with NASA's management of the space shuttle program. NASA had originally billed the shuttle as a space workhorse, capable of delivering high-payloads and satellites into upper orbit. Before the Challenger disaster, all of the country's orbital payloads would fly on the shuttle.
But the space shuttle was not nearly as safe, or reliable as it was cracked up to be. Richard Feynman, the famous physicist who served on the post-disaster investigation, estimated that the odds of losing a shuttle were one-in-a-hundred, far lower than NASA's more tolerable one-in-a-hundred thousand official estimate, reports Popular Mechanics.
"When the shuttle turned out to be not what we thought it was, all those downstream visions began to crumble," Howard McCurdy, a specialist in space policy at American University told USA Today. "The business model collapsed, and it wasn't just the business model for shuttle, it was the business model for shuttle, station, Mars, the moon. ... It was like a corporation going down."
Over concerns about the shuttle's reliability, Reagan banned space shuttles from carrying commercial satellites. With that policy, the private space industry was established, reports CBC.
The final nail in the space shuttle's coffin came in 2003, when the Columbia disintegrated over Texas while landing, sadly killing another seven astronauts.
The space shuttle was officially retired in 2011, and private space companies, including SpaceX, Jeff Bezos' Blue Origin, and the Sierra Nevada Corporation, will begin supplying the International Space Station in 2017, reports Business Insider's Jess Orwig.
When asked about the future of private spaceflight, Bezos himself waxed philosophical to Space.com, "Our biggest opponent in this endeavor is gravity."
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Like a zombie, the Milky Way galaxy may already be dead but it still keeps going.
Our galactic neighbor Andromeda almost certainly expired a few billion years ago, but only recently started showing outward signs of its demise.
Galaxies seem to be able to “perish” — that is, stop turning gas into new stars — via two very different pathways, driven by very different processes.
Galaxies like the Milky Way and Andromeda do so very, very slowly over billions of years.
How and why galaxies “quench” their star formation and change their morphology, or shape, is one of the big questions in extragalactic astrophysics.
We may now be on the brink of being able to piece together how it happens. And part of the thanks goes to citizen scientists who combed through millions of galactic images to classify what’s out there.
Galaxies are dynamic systems that continually accrete gas and convert some of it into stars.
Like people, galaxies need food. In the case of galaxies, that “food” is a supply of fresh hydrogen gas from the cosmic web, the filaments and halos of dark matter that make up the largest structures in the universe. As this gas cools and falls into dark matter halos, it turns into a disk that then can cool even further and eventually fragment into stars.
As stars age and die, they can return some of that gas back into the galaxy either via winds from stars or by going supernova. As massive stars die in such explosions, they heat the gas around them and prevent it from cooling down quite so fast. They provide what astronomers call “feedback”: star formation in galaxies is thus a self-regulated process. The heat from dying stars means cosmic gas doesn’t cool into new stars as readily, which ultimately puts a brake on how many new stars can form.
Most of these star-forming galaxies are disk- or spiral-shaped, like our Milky Way.
But there’s another kind of galaxy that has a very different shape, or morphology, in astronomer-parlance. These massive elliptical galaxies tend to look spheroidal or football-shaped. They’re not nearly so active — they’ve lost their supply of gas and therefore have ceased forming new stars. Their stars move on far more unordered orbits, giving them their bulkier, rounder shape.
These elliptical galaxies differ in two major ways: They no longer form stars and they have a different shape. Something pretty dramatic must have happened to them to produce such profound changes. What?
The basic division of galaxies into star-forming spiral galaxies blazing in the blue light of massive, young and short-lived stars, on the one hand, and quiescent ellipticals bathed in the warm glow of ancient low-mass stars, on the other, goes back to early galaxy surveys of the 20th century.
But, once modern surveys like the Sloan Digital Sky Survey (SDSS) began to record hundreds of thousands of galaxies, objects started emerging that didn’t quite fit into those two broad categories.
A significant number of red, quiescent galaxies aren’t elliptical in shape at all, but retain roughly a disk shape. Somehow, these galaxies stopped forming stars without dramatically changing their structure.
At the same time, blue elliptical galaxies started to surface. Their structure is similar to that of “red and dead” ellipticals, but they shine in the bright blue light of young stars, indicating that star formation is still ongoing in them.
How do these two oddballs — the red spirals and the blue ellipticals — fit into our picture of galaxy evolution?
As a graduate student in Oxford, I was looking for some of these oddball galaxies. I was particularly interested in the blue ellipticals and any clues they contained about the formation of elliptical galaxies in general.
At one point, I spent a whole week going through almost 50,000 galaxies from SDSS by eye, as none of the available algorithms for classifying galaxy shape was as good as I needed it to be. I found quite a few blue ellipticals, but the value of classifying all of the roughly 1 million galaxies in SDSS with human eyes quickly became apparent. Of course, going through a million galaxies by myself wasn’t possible.
A short time later, a group of collaborators and I launched GalaxyZoo.org and invited members of the public — citizen scientists — to participate in astrophysics research. When you logged on to Galaxy Zoo, you’d be shown an image of a galaxy and a set of buttons corresponding to possible classifications, and a tutorial to help you recognize the different classes.
By the time we stopped recording classifications from a quarter-million people, each of the 1 million galaxies on Galaxy Zoo had been classified over 70 times, giving me reliable, human classifications of galaxy shape, including a measure of uncertainty. Did 65 out of 70 citizen scientists agree that this galaxy is an elliptical? Good! If there’s no agreement at all, that’s information, too.
Tapping into the “wisdom of the crowd” effect, coupled with the unparalleled human ability for pattern recognition, helped sort through a million galaxies and unearthed many of the less common blue ellipticals and red spirals for us to study.
The crossroads of galaxy evolution is a place called the “green valley.” This may sound scenic, but refers to the population between the blue star-forming galaxies (the “blue cloud”) and the red, passively evolving galaxies (the “red sequence”). Galaxies with “green” or intermediate colors should be those galaxies in which star formation is in the process of turning off, but which still have some ongoing star formation — indicating the process only shut down a short while ago, perhaps a few hundred million years.
As a curious aside, the origin of the term “green valley” may actually go back to a talk given at the University of Arizona on galaxy evolution where, when the speaker described the galaxy color-mass diagram, a member of the audience called out: “the green valley, where galaxies go to die!” Green Valley, Arizona, is a retirement community just outside of the university’s hometown, Tucson.
For our project, the really exciting moment came when we looked at the rate at which various galaxies were dying. We found the slowly dying ones are the spirals and the rapidly dying ones are the ellipticals. There must be two fundamentally different evolutionary pathways that lead to quenching in galaxies. When we explored these two scenarios — dying slowly, and dying quickly — it became obvious that these two pathways have to be tied to the gas supply that fuels star formation in the first place.
Imagine a spiral galaxy like our own Milky Way merrily converting gas to stars as new gas keeps flowing in. Then something happens that turns off that supply of fresh outside gas: perhaps the galaxy fell into a massive cluster of galaxies where the hot intra-cluster gas cuts off fresh gas from the outside, or perhaps the dark matter halo of the galaxy grew so much that gas falling into it gets shock heated to such a high temperature that it cannot cool down within the age of the universe. In any case, the spiral galaxy is now left with just the gas it has in its reservoir.
Since these reservoirs can be enormous, and the conversion of gas to stars is a very slow process, our spiral galaxy could go on for quite a while looking “alive” with new stars, while the actual rate of star formation declines over several billion years. The glacial slowness of using up the remaining gas reservoir means that by the time we realize that a galaxy is in terminal decline, the “trigger moment” occurred billions of years ago.
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The Andromeda galaxy, our nearest massive spiral galaxy, is in the green valley and likely began its decline eons ago: it is a zombie galaxy, according to our latest research. It’s dead, but keeps on moving, still producing stars, but at a diminished rate compared to what it should if it were still a normal star-forming galaxy. Working out whether the Milky Way is in the green valley — in the process of shutting down — is much more challenging, as we are in the Milky Way and cannot easily measure its integrated properties the way we can for distant galaxies.
Even with the more uncertain data, it looks like the Milky Way is just at the edge, ready to tumble into the green valley. It’s entirely possible that the Milky Way galaxy is a zombie, having died a billion years ago.
Kevin Schawinski, assistant professor of galaxy and black hole astrophysics, Swiss Federal Institute of Technology, Zurich.
This article was originally published on The Conversation. Read the original article.
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Aliens could be out there. We simply don't know it yet.
Part of the reason we're still pretty clueless is because our technology is still in its infancy.
But scientists and engineers are rapidly ramping up the tools we'll need to answer one of humanity's most compelling questions: Are we alone?
Here are six ways scientists plan to delve into this mystery in the recent and coming years.
LEARN MORE: The 12 most compelling scientific findings that suggest aliens are real
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Read more about why we should send humans to Mars here.
Learn more about NASA's upcoming mission to Europa here.
Read about what the former director of the Center for SETI Research at the SETI Institute, Jill Tarter thinks about aliens here.
One of SpaceX's competitors made a risky move last year that could now cost it a multi-billion dollar contract with the US Air Force.
At a Senate Armed Services Committee hearing on Wednesday, Air Force Secretary Deborah Lee James said that Air Force staff were currently investigating the repercussions of prematurely ending its contract with the launch services provider United Launch Alliance.
Under the contract — called the EELV (Evolved Expendable Launch Vehicle) Launch Capability (ELC) contract — the US Air Force agrees to pay ULA $800 million per year from 2006 to 2019 to ferry national security satellites to space.
There's just one problem: SpaceX, the private spaceflight company owned and founded by billionaire entrepreneur Elon Musk.
In 2006, when the Air Force first awarded the contract to ULA, no one could have foreseen how fast and furious Musk's private spaceflight company would rise to success.
And after SpaceX had demonstrated itself as a reliable launch services provider by the start of 2014, Musk decided that he wanted in on some of ULA's action.
At the time, ULA was the only spaceflight company certified to conduction national security launches.
Because the US Air Force had not certified SpaceX rockets for national security launches, ULA was enjoying a secure and lucrative monopoly on the market to ferry sensitive and costly military satellites into orbit.
But now, the tables could turn in favor of SpaceX because of a potentially fatal decision that ULA made last year.
In May 2015, the US Air Force upped the competition for ULA by certifying SpaceX for those coveted national security launches, making ULA and SpaceX the only two spaceflight companies certified to perform these missions.
When the time finally came last November for the two companies to compete for the first time to launch a US Air Force GPS navigation satellite, ULA pulled out and didn't submit a proposal.
That move raised a lot of eyebrows from the US Air Force, who was paying ULA nearly $1 billion a year in tax payer's dollars to perform such launches. And now, it could cost ULA its contract.
“I was very surprised and disappointed when ULA did not bid on a recent GPS competitive launch opportunity,” James told Defense News. “And given the fact that there are taxpayer dollars involved with this ELC arrangement ... I've asked my legal team to review what could be done about this.”
If the US Air Force decides to cancel its contract with ULA, then ULA will have a very hard time surviving as a company, let alone competing with SpaceX for upcoming national security launches.
And it could give SpaceX, which is already scheduled to launch more than half of the world's commercial satellite missions this year, a sizeable advantage on the US military spaceflight market.
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NOW WATCH: The most difficult space mission in history is coming
While the Apollo missions are the most famous, the Space Transportation System (STS) shuttle program was the most productive in NASA's history.
From 1980 to 2011, NASA launched 135 missions. Over 350 astronauts deployed 180 payloads, including satellites and space probes. Crews sent the International Space Station and the Hubble telescope into orbit.
Two shuttle flights ended in disaster: the Challenger on January 28, 1986, just 73 seconds after launch; and the Columbia on February 1, 2003, when it was returning to Earth.
Both tragedies shook the nation.
But the shuttle program didn't stop. More pioneers continued to take to the skies, making discoveries we could never make on the ground.
Adam Rutherford led a team at Nature that put together an incredible video documenting every space shuttle NASA ever launched. They combed through around 100 hours of footage that had been recorded on VHS tapes, which NASA sent them 15 at a time.
"We'd go through hours of footage to get a few seconds' worth," he told The Open Notebook, in an interview about the months-long project.
The moving video they created will likely make you cry — with sorrow for the astronauts lost, but also with wonder that we could accomplish such greatness.
Set aside eight minutes to watch it, and appreciate the incredible drive, genius, and bravery that went into the shuttle program.
As Commander Chris Ferguson said when the last shuttle mission, STS-135, rolled to a stop: "Although we got to take the ride, we sure hope that everybody who has ever worked on, or touched, or looked at, or envied or admired a space shuttle was able to take just a little part of the journey with us."
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The ancient Babylonians used geometry to calculate the position of Jupiter 1,400 years before scholars in Europe were believed to have come up with the technique. The discovery is the earliest ever example of geometry being used to calculate positions of spacetime – and could indicate Western science was influenced by these ancient astronomers.
Mathieu Ossendrijver, a professor at Humboldt University in Berlin who specializes in Babylonian astronomy, made the discovery by studying five tablets dating to between 350 and 50 BC. He had long known of four of the tablets – but they were damaged, meaning he could not fully translate the information on them. He knew they involved geometrical computations, and thought they may involve Jupiter, but did not have enough information to go on to make any solid claims.
However, in 2015, he came across a set of photographs showing a previously unknown Babylonian astronomical tablet held at the British Museum in London. After examining it, he realized it related to the other four – acting as a key to unlock the information they contained. "The fifth one, was essential for forming a sense of the whole," he told IBTimes UK.
"All these questions were solved by this new tablet. Because it contains exactly the same computation in terms of numbers and it definitely deals with Jupiter. It was then possible to understand the others. It definitely deals with Jupiter. The trapezoid describes the motion of Jupiter. We were then able to reinterpret these tablets in spite of the fact they were damaged. It was a eureka moment."
The tablets contain geometrical calculations based on a trapezoid's area, using its long and short sides. They showed the two intervals from when Jupiter first appears on the horizon, depicting it at 60 and 120 days. They also worked out the time when Jupiter has covered half the 60 day distance by positioning the trapezoid into smaller ones. The findings are published in the journal Science.
Ossendrijver said we already knew a great deal about the ancient Babylonians were advanced in terms of their mathematical and astronomical abilities. "But this bunch of tablets, this kind of geometry that we've now found, is another level of abstraction," he said. "It's a kind of geometry that is not found anywhere else in antiquity. It's geometrical objects in this trapezoid – essentially a rectangle with a slanted top. This trapezoid is not located in real space, like our 3D space in which we are living, in which the planets are moving. But it's found in a more abstract mathematical space. It describes how Jupiter's velocity changes with time.
"The horizontal axis is time, the vertical axis is velocity. This slanted topside which is orientated downwards represents how Jupiter's velocity decreases from day zero to day 60. So it's like a modern graph. This is totally new. We thought this was invented in 14th century in Oxford and Paris – groups of mathematicians were inventing these methods."
Jupiter was particularly important to the Babylonians. The five tablets analyzed were most likely found in Babylon and were written by astronomers who served as priests in the main temple. This temple was dedicated to Marduk, a god from ancient Mesopotamia patron deity of the city of Babylon. All of the gods were assigned a star or planet to represent – Marduk's was Jupiter.
Ossendrijver said it would have been no coincidence that five tablets with the same geometrical method dealt only with Jupiter and the same 60-day interval. While there is no evidence, he speculates that the priests would have had good reason to study Jupiter more intensely than the other planets. Whether Jupiter was used as a proof of concept, or whether they used this method to track the other planets is not yet known.
"I would like to think this method was also applied to other planets and maybe such tablets will be found one day. I simply don't know. It could be that it's one very clever astronomer who came up with this new method and he thought let's work it out with Jupiter and see where we go from there. Maybe it was not continued, or maybe we don't have the tablets that were produced after that for the other planets. Time will tell."
While the Babylonians are known to have been very advanced, the latest find adds to the complexity and sophistication of their astronomy. It shows, Ossendrijver said, that they understood connections between time, velocity and distance travelled in a modern way – something he says is quite amazing.
How and why they were doing these calculations is unclear – researchers only have tablets with instructions on how to do something. There are no tablets explaining how they came up with something.
"These tablets are very rare or non-existent. So we can only speculate what they were actually thinking about with this method – how they perceived it. I like to think of the Babylonians as fully modern people that had the same cognitive skills as us, so I like to think that the astronomer who invented this was very proud of it or understood that it was something very new and very special."
Ossendrijver will continue to work with these other Babylonian astronomical tablets. He released his first book on them in 2012, and is currently in the process of writing a second that involves tables and numbers that describe positions in the sky.
Furthermore he is working with a colleague from Oxford to find links between the Babylonians and late Egyptian texts from the Roman period. The texts were found to have Babylonian astronomy relating to Mercury – showing their work had travelled to Egypt and the people there.
Summing up the latest research, astronomy historian John Steele of Brown University (who was not involved in the study), told Science Magazine Ossendrijver's finding was "an extremely important contribution to the history of Babylonian astronomy, and more generally to the history of science."
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