In the last few days, we have learned that the Bezos brothers are heading to a suborbital spaceflight on July 20 using Blue Origin’s New Shepard rocket. I guess this is putting Jeff Bezos’ money where his mouth is as he and his brother Mark fly to the edge of space on the anniversary date of America’s moon landing in 1969.
New Shepard has been tested 15 times without any humans aboard. This will be the first of what Bezos hopes will become a space tourism business. It will mark the first time a billionaire has gone to space. Later this year, Richard Branson hopes to be the second person with more money than he needs and knows what to do with. He will fly in the Spaceship2 Unity suborbital spaceplane to the edge of space. I think both men are trying to goad Elon Musk to take a ride in the future either with Dragon and Falcon 9 or with the Starship. Musk has already stated he’s not going to Mars, just sending others there.
Ion drives are different from chemical rocket motors. You can’t get off the planet with the former. But once in space, they can get you to places with very little fuel and save time. Both NASA and the China National Space Administration (CNSA) have been experimenting with this form of propulsion.
Ion drives use electric propulsion to accelerate a spacecraft once in space. In Earth’s atmosphere and having to fight gravity, it’s a losing battle for this type of engine, but in space, the drive creates acceleration by stripping gas molecules of electrons and shooting the remaining positive ions out the back to create thrust. Theoretically, a spacecraft powered by ion thrusters would incrementally gain speed over time and, for example in a voyage to Mars, could attain speeds five times greater than current chemical rockets. That would cut down the time it would take for an Earth to Mars and return trip from the current eight months each way to a little more than a month.
CNSA has been perfecting ion thrusters and has been firing one down here on Earth continuously for 11 months. Ion thrusters require powerful magnets to direct the ion stream, and specialized ceramic materials to protect them from radiation damage.
China’s first big space test of the technology will be on the Tiangong Space Station. Its first module, Tianhe, launched in April has 4 ion thrusters that use electricity generated from the solar panels to power the drives.
A yet to be tapped resource, electricity from space is being looked at seriously by NASA, the U.S. Department of Defense, and American companies as the next frontier in renewable, clean energy.
Today, solar powers our satellites in orbit, and solar panels harvest the photons from sunlight and convert them to electricity to power businesses and homes. But what if we could capture solar energy using large photovoltaic arrays and beam that energy to Earth?
Back in 2008, Ben Bova, a science-fiction novelist with 120-authored books under his belt, and President Emeritus of the National Space Society wrote a letter to President-Elect Obama, about harvesting solar energy from space to wean the U.S. off fossil fuels.
In it, Bova noted that the sun generates 386 trillion megawatts of energy per second, a steady, continuous, clean energy resource that could be harvested by solar-power satellites (SPS). These satellites once in orbit would deliver electricity to Earth by microwave. The microwave beam would be diffuse so that any animal or plant life would be unaffected by it. Receiving stations would be located in remote areas and would be linked into a modernized grid.
SPS would convert sunlight to energy far more efficiently than photovoltaic panels do today here on Earth. SPS wouldn’t have to deal with atmospheric interference. shifting of the panels to maximize the amount of energy received, and the daily loss of sunlight at nightfall.
Currently, Japan, China, Russia, the European Union, and the United States are considering building an SPS. The U.S. has plans aimed at a test deployment using the International Space Station sometime in 2023. China has announced plans to have an SPS in orbit by no later than 2030. And who knows if Blue Origin or SpaceX won’t decide to get into the business themselves.
An SPS could be a massive structure. Bova imagined a satellite with a surface area almost 13 square kilometres (5 square miles). It would be placed in a stationary orbit above the planet. The material costs for the first would rival the building of a nuclear power plant. But unlike anything built by humans in the past, an SPS would be assembled in orbit almost exclusively by robots using materials initially sent from Earth, but the vast majority harvested from captured asteroids or the lunar surface.
A mesh network of SPS could theoretically replace all terrestrial power generation sources as material harvesting and manufacturing capacity in space grows. By 2100, then we would be in a position to no longer need terrestrial power generation to deliver power to every corner of the planet. At least, that was Bova’s dream which yet may turn into a reality as we here on Earth end our fossil fuel energy dependency.
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Natalya Bailey, CEO of Accion, recently talked about the propulsion technology to a conference at MIT’s Sloan School of Management, describing it as scalable from as small as a nanometer to a multiple TILE array to serve as a propulsion system for large satellite systems. Seen in the image below each TILE features:
TILE uses ionic liquid electrospray propulsion. That it uses an electromagnetic field to shoot charged atomic particles in the direction required by its operators. How it differs from other ion propulsion systems is this. TILE is really a thruster-chip assembly containing hundreds of emitters beaming ions powered by a salt-based solution propellant. Each TILE module is composed of 36 thruster chips measuring 10 x 10 x 12.5 centimeters (4 x 4 x 5 inches). The salt-based propellant gets stored in very small tanks. The electronics is powered by attached solar panels with battery. Ions get drawn from the propellant when the electromagnetic field is fired up. The ions are then ejected in a beam in the opposite direction from the satellite or spaceships planned direction creating forward thrust. TILEs can fire in two directions as can be seen in this YouTube posted video.
A small satellite weighing up to 200 kilograms can easily be propelled by 1 to 4 TILES. For larger objects, TILES can be strung together in an array to provide additional thrust. Because the TILES are lightweight, they are an attractive option for satellite and spacecraft builders. Accion believes a shoebox-sized array of TILES is all that would be needed for a voyage to Mars by a human-crewed spaceship.
In a recent article appearing in Bloomberg, Accion was rated as one of 50 startup companies deemed most promising to investors looking at emerging technologies and innovative business plays. I would suspect we will see this technology deployed in the very near future. The company states first flight will happen in 2018 and suspects that TILE technology will be used in the near future for satellites and spacecraft in orbit to raise, maintain and de-orbit, extending mission lifetimes without expending costly and toxic propellants into near space. And although ion propulsion can’t get you off the ground and out of Earth’s gravity well, once up in space, it becomes an excellent propulsion alternative to chemical-fuelled rocket engines.
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Advanced Ion Propulsion Engine Sets World Record
The Dawn robotic spacecraft has been using ion propulsion to help it on its journey to the Asteroid Belt. Since leaving Vesta in August of last year it has deployed the engine to push it to its ultimate destination in 2015, the dwarf planet Ceres. But here on Earth another ion propulsion engine has been operating continuously for even longer – a total of 5 1/2 years.
Developed at NASA’s Glenn Research Center in Cleveland, Ohio, the engine goes by the acronym NEXT (NASA Evolutionary Xenon Thruster). Ion propulsion uses electricity generated from solar panels or another power source to heat up xenon propellant which then gets pushed out the back of the combustion chamber to provide thrust. What makes NEXT interesting is it achieves thrust capable of accelerating a spacecraft to 145,000 kilometers (90,000 miles) per hour over a period of time using only 870 kilograms (1,918 pounds) of fuel. A chemical rocket would need 10,000 kilograms (22,000 pounds) to achieve similar results once deployed in space.
A Company with the Name Soylent Raises $800,000 for a Food Replacement Product
It is hard to know whether this is for real or a hoax but a company using the crowdfunding launch tool, Crowdhoster, claims to have raised $800,000 in 3 hours with almost 6,500 people wanting to be the first to get its product called Soylent.
What is Soylent? A customizable total food replacement that comes in powdered form. All you do is mix it with water and it has all the nutritional needs normally derived from balanced eating. On its promotion site the founders state you no longer need to go to a grocery store to buy food. No more cooking and after dinner clean ups. No more eating cute little chickens and calves. And no more unsightly trash from packaging or wasted food. Soylent has a long shelf life. It requires no preparation other than mixing it with water. And its first manufactured batch ships in July. It will be vegetarian, halal and lactose free. Didn’t see a kosher stamp but I guess halal is close enough for those who care.
If you are familiar with the movie Soylent Green and that products “human” content then you may feel a bit on the squeamish side about a company that has chosen this moniker. But lots of people have ponied up $10 or more to be first in line to get Soylent which right now is only available in the United States, Canada, the UK and Mexico. If you miss getting in on this first batch a second is expected to be shipping in the fall. Aah, the shape of things to come and it isn’t even 2022 yet.
Nano Sensors Smell Melanomas
Researchers have known for some time that dogs can smell cancer in a human. That’s because normal and diseased human skin produce airborne chemical signatures in the form of volatile organic compounds or VOCs. Different diseases emit different odors which are only discernible to a keen sense of smell. That’s why some dog breeds whose sense of smell is as much as 10,000 times better than us have been used to detect skin, lung and other forms of cancer.
But what happens if you don’t have a dog around? Well a group of researchers and scientists from the Monell Chemical Senses Center in Philadelphia decided to try and develop a nanotechnology with equivalent capability to a dog’s nose. Reported in next month’s issue of the Journal of Chromatography, the researchers constructed nano-sized carbon tubes which they coated with strands of DNA bioengineered to recognize odor molecules. The result a tool that distinguishes the difference in smell between normal and melanoma cells.
But for those of you who are dog lovers there’s no walking this technology and it won’t play fetch.
If You See This Ball in a Farmer’s Field Don’t Kick It
It is called Rosphere, a globe-shaped robot packed with sensors and a mechatronic internal mechanism that enables it to roll on its own. It is a product born of a research team at the Universidad Politécnica de Madrid. Their goal was to develop a robot that could move over any type of farm terrain collecting data without disturbing the crops. The device can be packed with different sensors for measuring soil moisture levels, ambient temperature, and chemical signatures to assist farmers in improving crop yields. And Rosphere isn’t limited to agricultural applications. It can be used to explore and study almost any terrain. If it gets stuck, remote operators can connect to it and get its mechatronic system moving again.
New Nuclear Fuel May Make Fission Reactors Much Safer
An Idaho State University research team has successfully manufactured a crystalline non-radioactive substitute for uranium or plutonium. It is uniformly structured crystallized uranium oxide with all of its atoms perfectly aligned. It looks a lot like a lump of glass but it has a lot of scientists and engineers working in the nuclear industry excited about its potential to produce a better and safer fuel for future reactors.
Today’s nuclear fuels consist of pellets that have random crystalline structure. This makes them difficult to model for the purpose of studying heat flow through the reactor. With a uniform uranium crystal, however, scientists will be able to study material behaviour in much greater detail and thus manufacture much safer nuclear fuel.
A Postscript
This week I watched and read about the Chinese taikonauts showing school children how water forms a sphere in a vacuum, and how they themselves can float in zero gravity. It was like a flashback to the 1970s when we saw similar demonstrations from space by crews on NASA’s Skylab and the Soviet Salyut modules. And that made me wonder why China isn’t involved like other nations with the International Space Station (ISS) and is having to start back at square one to develop its own human presence in space. Why step back 40 years when the world is about to see the first commercial suborbital and low-Earth orbit human spaceflights?
To me it appears the geopolitics of the old Cold War continue to isolate China so that it has to reinvent its own version of human space travel. Isn’t that a colossal waste of time and money?
When you consider that China in most other ways has become an integral part of our world community why is the country isolated from the rest of us when it comes to space science? After all China holds the largest amount of U.S. securities. It is America’s largest trading partner. It is a healthy competitor to the U.S., Canada and other countries in many fields including supercomputers. But when it comes to space it somehow or other doesn’t get let in the door to join the consortia of nations advancing space science and technology onboard the ISS. Yet when you consider that China is graduating more engineers today than the United States and Russia combined, wouldn’t it make sense to have these graduates contribute to our collective advancement in space?
Just asking!
That’s it for this week. Hope you found my selection of headlines interesting. If you encounter a breaking technology or science story that you feel belongs here, don’t be shy. Drop me a note and I’ll be happy to do the research and writing and acknowledge your contribution along the way.
– Len Rosen
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One justification comes from a NASA spokesperson who has wrapped this mission in the sacred cloak of saving civilization from near-Earth objects that could collide with the planet such as the one over Chelyabinsk on February 14 of this year. The rationale would be to build and demonstrate a technology solution for identifying, targeting and capturing Earth-threatening space rocks and moving them out of harms way.
What are we expecting in terms of new technology from such a mission? NASA intends to build what they are calling high-powered solar-electric propulsion (SEP) for the purpose of achieving rendezvous, capture and redirect, and state that without this technology the mission would not be possible. Once demonstrated SEP would be used for future telecommunications satellites and other Deep Space mission objectives.
So what is SEP? You may know it by its other name, ion propulsion, a system that NASA has successfully demonstrated with Dawn, the robotic spacecraft that recently visited Vesta and is now on its way to Ceres in the Asteroid Belt. So if we have already shown that ion propulsion works what needs further testing? Is there something different about the SEP planned for the mission to capture an asteroid?
It appears there is because calling it just SEP is actually a misnomer. What NASA intends to deploy is a hybrid chemical-SEP system. Chemical rockets would lift heavy payloads of components from the gravity well of Earth to low-Earth orbit. You couldn’t use SEP to do that. Once fully assembled and fueled SEP would be deployed to push the spacecraft into higher and higher orbits. This would be a slow process that would take several months. Once the spacecraft reached its destination point in Deep Space a chemical rocket with capsule and humans aboard would set off from Earth to rendezvous and dock. There are several potential scenarios that might ensue. The SEP robotic spacecraft could capture the asteroid on its own and bring it to the rendezvous point. Or the two together could use chemical thrust combined with SEP to set off for a rendezvous and capture of the asteroid. Return to Earth would involve an initial chemical rocket burn plus SEP to generate additional thrust. Will the SEP used for this mission differ from Dawn? Quite significantly! It will be much larger using more efficient solar panels and ion thrusters capable of putting out hundreds instead of tens of kilowatts.
What advantage will be gained by developing the chemical-SEP hybrid? The use of chemical rockets to get to low-Earth orbit will give NASA the best bang for the buck, while the deploying of SEP once in orbit will eliminate the need to carry large payloads of chemical fuel for use in spaceflight. This should save a considerable amount of money.
In addition assembling spacecraft for human occupation in low-Earth orbit rather than launching them fully assembled from the Earth surface will give NASA the capability to build heavier, better shielded human space habitats that can initially exploit SEP technology for travel, and later on magneto-plasma or even nuclear-powered propulsion systems.
So “catch a falling star” or in this case “asteroid” may help NASA catapult human voyagers to Mars and the Deep Space beyond. Let’s see if they get the money from Congress to move ahead.
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How will we manage it? There are a number of technologies already developed or in the developing stages that we can use and enhance to help us get farther than we are today. Some of these technologies are suitable for human space flight while others would better serve us in robotic or pay load specific missions.
Ion Propulsion Engines
Ion propulsion has been used for two robotic space missions to visit asteroids – Hayabusa and Dawn. These engines work by taking a very small amount of gas and accelerating it to very high speeds. Chemical rockets do the reverse, taking large amounts of gas and spewing it out at slow speeds.
Ion propulsion systems are very economical in their use of fuel as opposed to chemical rockets which use fuel rapidly. Ion propulsion engines require a continuous electrical charge to operate and can run on fumes. That’s why missions like Hayabusa and Dawn deployed very large solar arrays to provide the necessary power to not just run on board equipment but keep the engines pushing the spacecraft forward.
Ion propulsion, however, is not a suitable technology for human space flight. In providing very little thrust constantly by shooting gas molecules out the back of the rocket motor at high speed it slowly gains speed over time. For the Dawn mission to Vesta and Ceres its ion propulsion system added incremental velocity once it had escaped Earth’s gravity at a rate of approximately 800 kilometers (500 miles) per hour per month of operation. That type of thrust is equivalent to pushing the spacecraft forward by pushing out a couple of drops of water. For a robotic mission slow and steady while conserving fuel may make a lot of sense. But you wouldn’t want to subject a human expedition to other planets with this technology.
Solar Sails
So ion propulsion is not a suitable choice. What about solar sails? This is another in-space propulsion technology. It requires no fuel other than getting the material that constitutes the sail into low-Earth orbit. Once there the sail unfurls and as photons from sunlight strike its reflective material, the sail slowly begins to provide thrust. Solar sails are lightweight, super-thin and massive in size. Japan deployed a solar sail on its Venus interplanetary mission named IKAROS in 2010. NASA has also deployed a sail, the NanoSail-D, a spacecraft that unfurled its gleaming sheet of space-age fabric 650 km above Earth in early 2011.
Solar sails like ion propulsion are not technologies designed to get from Point A to B in the shortest period of time. They are suitable for unmanned missions where time plays less of a factor. A good use of a solar sail would be an unmanned payload mission to deliver a large amount of materials into orbit around Mars. Such a voyage could take many years and could be launched well ahead of a manned mission that would follow and then utilize the material deployed by the solar-sail driven spacecraft.
Nuclear Thermal Engines
We have been using RTG (Radioisotope Thermal Generators) in space on missions to the outer planets for many years. RTGs use the heat from radioactive decay of plutonium fuel to provide energy and warmth to robotic spacecraft deployed in deep space. We deploy RTGs as a substitute for solar photovoltaics in missions where solar arrays cannot gather sufficient energy from sunlight. But the energy we derive from RTGs is not meant to be a propulsive force.
A nuclear thermal engine (NTE) on the other hand is intended to be used as a rocket providing the kind of thrust we obtain from chemical rockets. NTEs use an on board thermonuclear reactor to heat a fuel like liquid hydrogen. The fuel circulates around the core of the reactor in the same way water is heated in nuclear power stations on Earth to create steam that drives turbines. Substitute an engine nozzle for a turbine and you have a rocket with multiple NTEs capable of delivering thousands to millions of pounds of thrust.
Early NTE experiments by the Soviet Union used ammonia and alcohol as the propellant. But the United States developed a prototype called NERVA, that used liquid hydrogen. The choice of this fuel seems appropriate since the American space program in the 1960s became proficient in the use of hydrogen and today have built significant expertise in its usage for space flight.
NTE has advantages over chemical rockets. You only need to carry the hydrogen on board. You don’t need any oxidizer to create ignition. You can even consider adding hydrogen fuel to your tanks while en-route to your space destination using a giant cow-catcher to capture hydrogen atoms in space. That means you can go a lot farther and faster than with any of the technologies previously described. NTE technology has another benefit over chemical rockets. It is less complex, requiring fewer working parts so there is less chance of a mechanical failure.
The biggest drawback is radioactivity. NTE technology uses uranium for the reactor core. Although the technology is shut off until it reaches Earth orbit there is the potential for an accident during the launch phase. To counter the potential of atmospheric radioactivity in the event of such an accident, scientists propose encasing the uranium in tungsten. Tungsten has a high heat resistance and would keep the reactor core intact to minimize radioactivity escaping into the atmosphere.
NTE technology remains shut off until deployed in Earth orbit and the radioactivity generated gets dispersed into outer space once the engine is operational. Would a human crew be at risk of exposure? With proper shielding an NTE poses much less of a threat in space flight than does exposure to natural radiation from cosmic rays.
But NTE technology may be supplanted by another – the plasma engine.
Plasma Engines
From NERVA to VASIMIR, NASA’s Advanced Space Propulsion Laboratory is experimenting with a technology that could send a human crew to Mars and back in around four months compared to current chemical rockets which would take 10 months. Working with a company, Ad Astra, the developer of the technology, NASA would like to build 10 to 200-megawatt engines using this technology for human, robotic and payload missions to deep space.
What does VASIMIR stand for? Variable Specific Impulse Magneto-plasma Rocket, an idea that was first proposed in 1973 by Dr. Franklin Chang Diaz, an MIT graduate who happens to also be a NASA astronaut.
Like ion propulsion engines VASIMIR can only operate in the vacuum of space with a low thrust to weight ratio. But unlike ion propulsion, the VASIMIR can achieve much greater thrust and power while using very little fuel.
Launched into space using conventional chemical rockets or by other launch technologies such as we described in our last blog, VASIMIR would be payload until deployed in orbit.
How does VASIMIR work? It uses a pair of radio wave emitters surrounded by magnets to turn cold hydrogen, argon, and xenon gases into superheated plasma. The first radio wave emitter heats the gas to a cold plasma state, about equal to the surface temperature of the Sun (6,000 Celsius or approximately 9,900 Fahrenheit degrees). The second emitter drives the temperature higher to levels equal to those at the Sun’s core (1,000,000 Celsius or 1,800,000 Fahrenheit degrees). The magnets generate a shaped series of fields that contain the superheated plasma directing it backward to vent out through nozzles creating forward thrust. The use of magnetic field containment means no physical points of contact and longer engine life.
Providing power to the radio wave emitters and creating the magnetic fields requires a lot of electricity. That’s why these engines are described in megawatt terms. For example a near-Earth robotic missions could be powered by solar array capable of generating 2 Megawatts. But for larger missions like the one proposed to Mars, the engine would require on board nuclear reactors capable of generating much more power. Building and launching nuclear reactors into low-Earth orbit capable of generating 200 Megawatts is a significant task and not one without risk. This may prove to be the biggest impediment to deploying VASIMIR for human interplanetary flight.
A small 200-kilowatt VASIMIR prototype will be deployed and tested on the International Space Station in 2013.
In our next blog on this subject will look at the technology that science fiction has described – antimatter and Warp drives. Are they for real or will they always be fantasy?
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Why Our Solar System Has An Asteroid Belt
The Asteroid Belt consists of rocky debris unevenly distributed in the zone between the planets Mars and Jupiter. This is not the only place where asteroids exist. Asteroid clusters can be found along both Jupiter and Mars’ orbital plane in front and behind the planets at specific points far enough away from them to remain reasonably stable. These asteroids are called Trojans. Other asteroids can be found at similar points along the orbital plane of Neptune. And some asteroids have odd orbits that take them near Earth. In fact scientists estimate neary 9,000 asteroids larger than 50 meters (over 150 feet) cross the orbit of our planet. These are the type of asteroids that pose a potential collision threat with our planet, the type of asteroid that has been associated with the mass extinction event of 65 millions year ago.
Why did asteroids form? Scientists theorize that the Asteroid Belt and Trojans represent the debris of the early Solar System. The Belt itself is believed to represent a zone within the Solar System that failed to form a planet because of the proximity of Jupiter with its massive gravitational pull. The normal gravitational accretion that led to Mars and Earth was stopped by Jupiter.
The Asteroid Belt itself is very thinly populated even though there are millions of these rocky chunks. We have discovered 220 larger than 100 kilometers (62 miles) in diameter of which the largest is Ceres, with a diameter of approximately 1,000 kilometers (620 miles). Total mass of all of the asteroids in the belt is estimated to be about 4% of our Moon with Ceres accounting for 1/3 of the total. Asteroids are unevenly distributed through the Belt. This was first observed in 1886, caused by resonances with Jupiter’s orbit, and named Kirkwood Gaps after the discoverer of the phenomenon. This uneven and thin distribution has made it much easier to launch missions to the outer planets with little in the way of actual debris posing a hazard to spacecraft.
In one mission, Galileo, the spacecraft actually rendezvoused with two asteroids, Gaspra and Ida, while on the way to Jupiter. Gaspra was potato shaped, riddled with craters and 19 kilometers (approximately 11 miles) in length. Ida looked similar and was 52 kilometers (approximately 33 miles) in length and even had its own moonlet named Dactyl, a fragment 1.5 kilometers (less than a mile) across. Dactyl circles Ida at a distance of 100 kilometers (62 miles). The two moons of Mars, Phobos and Deimos, (see image of Phobos below) appear to be asteroids captured by that planet’s gravity in the distant past.How long have asteroids been around? 4.6 billion years, as old as the Solar System itself. We have been observing them through Earth-based telescopes since the early 19th century. William Herschel was the first to coin the word asteroid to describe them. Spectroscopic analysis allows us to remotely determine their composition. Three-quarters of asteroids are carbonaceous chondrites, that is they are carbon-rich. The majority of the remainder are stony and metallic with many reddish in colour indicating the presence of large deposits of iron.
We Send Robot Spacecraft to Visit Asteroids
NEAR
In 1996 NASA launched the NEAR (Near Earth Asteroid Rendezvous) mission, a robotic spacecraft programmed to rendezvous with two asteroids, the first Mathilde, and the second Eros. In 1997 NEAR made its closest approach to Mathilde, viewing it from about 1,200 kilometers (750 miles). This provided scientists at John Hopkins University with a first close up look at a carbonaceous asteroid. Mathilde appeared as black as soot in images transmitted to Earth.
In February of 2000 NEAR rendezvoused with Eros, a 34 kilometer (21 miles) long asteroid and began a a year-long orbit around it at altitudes that varied from 3.2 kilometers (2 miles) to 52 kilometers (35 miles). In February 2001, although not a lander, NEAR descended to the surface of Eros providing detailed images of the asteroid’s surface.
Before NEAR it was thought that asteroids were metallic or carbonaceous rubble. Eros turned out to be neither. It’s rocky composition was similar to the Earth’s crust. It was geologically active with more than 100,000 craters wider than 15 meters (50 feet), many filled with rocky debris and dust to a depth of more than 90 meters (300 feet).
Hayabusa
In 2003 the Japanese Space Agency (JAXA) launched Hayabusa, a research spacecraft designed to rendezvous with an asteroid and return samples from its surface back to Earth. Hayabusa used an experimental ion propulsion system similar to the one deployed by Deep Space 1 in 1998. NASA developed and tested this technology in space for the first time in a mission to a comet in 1998. An ion propulsion system provides pretty tenuous power. In fact, if you were to use it to power a car it would take four days to accelerate from 0 to 100 kilometers (60 miles) per hour. But in space this type of engine creates a steady incremental push to a spacecraft and when operating over months and years provides a very effective propulsion system.
Hayabusa’s target was the near-Earth asteroid, Itokawa. It took two years and one gravity-assisted pass of Earth for Hayabusa to reach the asteroid, travelling over 2 billion kilometers (1.2 billion miles) to its target, 300 million kilometers (180 million miles) from Earth. Once there it studied Itokawa from altitudes between 3 and 20 kilometers (1.8 to 12 miles) touching down twice on its surface in November 2005 to take samples. Hayabusa then began its return to Earth in April 2007 with samples on board. Hayabusa’s sample was retrieved from a reentry capsule in June 2010.
Dawn
The Dawn spacecraft, launched in September 2007, today is orbiting Vesta, the first of the two asteroids it intends to visit between now and 2015. The spacecraft took four years to reach Vesta using a Martian fly by in 2009 to provide gravity assistance in accelerating the spacecraft on a trajectory to the asteroid. Upon arrival at Vesta, Dawn entered into orbit.
Dawn deploys a solar array that extends 19.7 meters (65 feet) to capture the much more tenuous light energy available to it at the distances it is operating in the Solar System. That same solar array provides the power to drive the xenon ion propulsion system, the third time this technology has been successfully deployed.
Dawn’s other technologies include: two framing cameras to provide detailed imaging in visible and infrared light, a gamma ray and neutron detector to measure the composition of each asteroid, a visble and infrared mapping spectrometer to work in association with the cameras to get accurate elevation reads and determine the minerals on each asteroids’ surface, and radio transmitters for sending signals to Earth and detecting gravity field variations.
In July of 2011 Dawn transmitted the first close- up images of Vesta (see the picture of the Snowman craters in the composite image of asteroids above). What it has discovered so far about this asteroid has revised our thinking about the geology of Asteroid Belt objects. For example there is evidence that Vesta first formed in a molten state as evidenced by its iron core. Vesta also has mountains, the largest more than twice the height of Mount Everest. Vesta also has dark, sooty deposits on its surface which appear to have arrived after the asteroid formed, probably delivered by collisions with carbonaceous Asteroid Belt objects. Like Eros, Vesta remains geologically active with its surface constantly being reworked over time as these collisions create debris and dust that settles into craters and narrow gullies that form ridge and valleys across parts of the asteroid.
When Dawn finishes its assignment at Vesta it will move on to its second objective in the Asteroid Belt, Ceres. Arrival is planned for August 2015 where Dawn will take up orbit to study the asteroid the same way it currently is studying Vesta. Ceres will be very different from Vesta. It’s larger and much further out in the Asteroid Belt. Earth observations indicate that it is composed of at least 25% water ice. So in its visit Dawn will give us an entirely different perspective on the composition of asteroids within the Asteroid Belt.
Why Mine Asteroids?
So we know that asteroids come in all shapes and sizes and are composed of everything from ores to ice. Which may explain why a wealthy group of entrepreneurs want to exploit asteroids as resources. A single asteroid could be worth billions of dollars if it were to be mined. And it will require billions of dollars in investment to succeed. The company plans to launch up to five space telescopes within the next two years to search for and identify asteroids of commercial value. Prospecting robotic spacecraft will follow within five to years. These robots will sample and assay target asteroids in preparation for a subsequent mission of robot miners and refiners who will then bring their precious cargo back to Earth. The economics of such a venture requires further study.
But it is far more likely that Planetary Resources will end up creating way stations in space by finding asteroids that are largely made of water, like Ceres but not as big. Water is the commodity that can become a precious resource when broken down into its constituent elements, oxygen and hydrogen. In addition water is life sustaining for any human presence in space. Water harvested in space can lead to Deep Space habitation where humans can provide a string of stops along the way to other destinations in the Solar System and beyond. But there will be many hurdles to overcome for this commercial plan to succeed including issues of legality and the development of whole range of new technology. We’ll explore the topic of the commercialization of space in subsequent blogs. So keep on reading and send me your questions.
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