Artist's conception of asteroid Bennu from the NASA film "Bennu's Journey." Credit: NASA/YouTube (screenshot)
We’ve been super-excited about the Philae landing recently, the first soft landing on a comet. But imagine if the spacecraft was equipped to bring a sample of Comet 67P/Churyumov–Gerasimenko back to Earth. What sort of secrets could we learn from examining the materials of the comet up close?
That dream will remain a dream for 67P, but guess what — if all goes to plan, that idea will execute for asteroid Bennu. Check out the new video above for more details on the audacious mission; below the jump is a brief mission description.
There is a mission expected to launch in 2016 called OSIRIS-REx that will spend two years flying to the asteroid to nab a sample, then will come back to Earth in 2023 to deliver it to scientists. This is exciting because asteroids are a sort of time capsule showing how the Solar System used to be in the early days, before gravity pulled rocks and ice together to gradually form the planets and moons that we have today.
“Scientists tell us that asteroid Bennu has been a silent witness to titanic events in the solar system’s 4.6 billion year history,” NASA wrote on a website commemorating the new video. “When it returns in 2023 with its precious cargo, OSIRIS-REx will help to break that silence and retrace Bennu’s journey.”
For more information on OSIRIS-REx, check out the mission’s website.
This diagram maps data gathered from 1994-2013 on small asteroids impacting Earth's atmosphere to create very bright meteors (bolides). The location of impacts from objects ranging from 1 meter (3 feet) to nearly 20 meters (60 feet) in size such as Chelyabinsk asteroid are shown globally. (Credit: Planetary Science, NASA)
How hazardous are the thousands and millions of asteroids that surround the third rock from the Sun – Earth? Since an asteroid impact represents a real risk to life and property, this is a question that has been begging for answers for decades. But now, scientists at NASA’s Jet Propulsion Laboratory have received data from a variety of US Department of Defense assets and plotted a startling set of data spanning 20 years.
This latest compilation of data underscores how frequent some of these larger fireballs are, with the largest being the Chelyabinsk event on February 15, 2013 which injured thousands in Russia. The new data will improve our understanding of the frequency and presence of small and large asteroids that are hazards to populated areas anywhere on Earth.
On Feb. 28, 2009, Peter Jenniskens (SETI/NASA), finds his first 2008TC3 meteorite after an 18-mile long journey. “It was an incredible feeling,” Jenniskens said. The meteorite which impacted in the Nubian Desert of Africa on Oct 7, 2008 was the first asteroid whose impact with Earth was predicted while still in space approaching Earth. Meteorite 2008TC3 and Chelyabinsk’s are part of the released data set. (Credit: NASA/SETI/P.Jenniskens)
The data from “government sensors” – meaning “early warning” satellites to monitor missile launches (from potential enemies) as well as infrasound ground monitors – shows the distribution of bolide (fireball) events. The data first shows how uniformly distributed the events are around the world. This data is now released to the public and researchers for more detailed analysis.
The newest data released by the US government shows both how frequent bolides are and also how effectively the Earth’s atmosphere protects the surface. A subset of this data had been analyzed and reported by Dr. Peter Brown from the University of Western Ontario, Canada and his team in 2013 but included only 58 events. This new data set holds 556 events.
The newly released data also shows how the Earth’s atmosphere is a superior barrier that prevents small asteroids’ penetration and impact onto the Earth’s surface. Even the 20 meter (65 ft) Chelyabinsk asteroid exploded mid-air, dissipating the power of a nuclear blast 29.7 km (18.4 miles, 97,400 feet) above the surface. Otherwise, this asteroid could have obliterated much of a modern city; Chelyabinsk was also saved due to sheer luck – the asteroid entered at a shallow angle leading to its demise; more steeply, and it would have exploded much closer to the surface. While many do explode in the upper atmosphere, a broad strewn field of small fragments often occurs. In historical times, towns and villages have reported being pelted by such sprays of stones from the sky.
NASA and JPL emphasized that investment in early detection of asteroids has increased 10 fold in the last 5 years. Researchers such as Dr. Jenniskens at the SETI Institute has developed a network of all-sky cameras that have determined the orbits of over 175,000 meteors that burned up in the atmosphere. And the B612 Foundation has been the strongest advocate of discovering of all hazardous asteroids. B612, led by former astronauts Ed Lu and Rusty Schweikert has designed a space telescope called Sentinel which would find hazardous asteroids and help safeguard Earth for centuries into the future.
Speed is everything. While Chelyabinsk had just 1/10th the mass of Nimitz-class super carrier, it traveled 1000 times faster. Its kinetic energy on account of its speed was 20 to 30 times that released by the nuclear weapons used to end the war against Japan – about 320 to 480 kilotons of TNT. Briefly, asteroids are considered to be any space rock larger than 1 meter and those smaller are called meteoroids.
Two earlier surveys can be compared to this new data. One by Eugene Shoemaker in the 1960s and another by Dr. Brown. The initial work by Shoemaker using lunar crater counts and the more recent work of Dr. Brown’s group, utilizing sensors of the Department of Defense, determined estimates of the frequency of asteroid impacts (bolide) rates versus the size of the small bodies. Those two surveys differ by a factor of ten, that is, where Shoemaker’s shows frequencies on the order of 10s or 100s years, Brown’s is on the order of 100s and 1000s of years. The most recent data, which has adjusted Brown’s earlier work is now raising the frequency of hazardous events to that of the work of Shoemaker.
The work of Dr. Brown and co-investigators led to the following graph showing the frequency of collisions with the Earth of asteroids of various sizes. This plot from a Letter to Nature by P. Brown et al. used 58 bolides from data accumulated from 1994 to 2014 from government sensors. Brown and others will improve their analysis with this more detailed dataset. The plot shows that a Chelyabinsk type event can be expected approximately every 30 years though the uncertainty is high. The new data may reduce this uncertainty. Tungunska events which could destroy a metropolitan area the size of Washington DC occur less frequently – about once a century.
The estimated cumulative flux of impactors at the Earth. The bolide impactor flux at Earth (Bolide flux 1994-2013 – black circles) based on ~20 years of global observations from US Government sensors and infrasound airwave data. Global coverage averages 80% among a total of 58 observed bolides with E > 1 kt and includes the Chelyabinsk Chelyabinsk bolide (far right black circle). This coverage correction is approximate and the bolide flux curve is likely a lower limit. The full caption is at bottom. (Credit: P. Brown, Letter to Nature, 2013, Figure 3)
Asteroids come in all sizes. Smaller asteroids are much more common, larger ones less so. A common distribution seen in nature is represented by a bell curve or “normal” distribution. Fortunately the bigger asteroids number in the hundreds while the small “city busters” count in the 100s of thousands, if not millions. And fortunately, the Earth is small in proportion to the volume of space even just the space occupied by our Solar System. Additionally, 69% of the Earth’s surface is covered by Oceans. Humans huddle on only about 10% of the surface area of the Earth. This reduces the chances of any asteroid impact effecting a populated area by a factor of ten.
Altogether the risk from asteroids is very real as the Chelyabinsk event underscored. Since the time of Tugunska impact in Siberia in 1908, the human population has quadrupled. The number of cities of over 1 million has increased from 12 to 400. Realizing how many and how frequent these asteroid impacts occur plus the growth of the human population in the last one hundred years raises the urgency for a near-Earth asteroid discovery telescope such as B612’s Sentinel which could find all hazardous objects in less than 10 years whereas ground-based observations will take 100 years or more.
The estimated cumulative flux of impactors at the Earth. The bolide impactor flux at Earth (Bolide flux 1994-2013 – black circles) based on ~20 years of global observations from US Government sensors and infrasound airwave data. Global coverage averages 80% among a total of 58 observed bolides with E > 1 kt and includes the Chelyabinsk Chelyabinsk bolide (far right black circle). This coverage correction is approximate and the bolide flux curve is likely a lower limit. The brown-coloured line represents an earlier powerlaw fit from a smaller dataset for bolides between 1 – 8 m in diameter15. Error bars represent counting statistics only. For comparison, we plot de-biased estimates of the near-Earth asteroid impact frequency based on all asteroid survey telescopic search data through mid- 2012 (green squares)8 and other earlier independently analysed telescopic datasets including NEAT discoveries (pink squares) and finally from the Spacewatch (blue squares) survey, where diameters are determined assuming an albedo of 0.1. Energy for telescopic data is computed assuming a mean bulk density of 3000 kgm-3 and average impact velocity of 20.3 kms-1. The intrinsic impact frequency for these telescopic data was found using an average probability of impact for NEAs as 2×10-9 per year for the entire population. Lunar crater counts converted to equivalent impactor flux and assuming a geometric albedo of 0.25 (grey solid line) are shown for comparison9, though we note that contamination by secondary craters and modern estimates of the NEA population which suggest lower albedos will tend to shift this curve to the right and down. Finally, we show estimated influx from global airwave measurements conducted from 1960-1974 which detected larger (5-20m) bolide impactors (upward red triangles) using an improved method for energy estimation compared to earlier interpretations of these same data.
As of November 2014, these are all of the planetary, lunar and small body surfaces where humanity has either lived, visited, or sent probes to. Composition by Mike Malaska, updated by Michiel Straathof. Image credits: Comet 67P/C-G [Rosetta/Philae]: ESA / Rosetta / Philae / CIVA / Michiel Straathof. Asteroid Itokawa [Hayabusa]: ISAS / JAXA / Gordan Ugarkovic. Moon [Apollo 17]: NASA. Venus [Venera 14]: IKI / Don Mitchell / Ted Stryk / Mike Malaska. Mars [Mars Exploration Rover Spirit]: NASA / JPL / Cornell / Mike Malaska. Titan [Cassini-Huygens]: ESA / NASA / JPL / University of Arizona. Earth: Mike Malaska
Correction, 11:33 a.m. EST: The University of Central Florida’s Phil Metzger points out that the image composition leaves out Eros, which NEAR Shoemaker landed on in 2001. This article has been corrected to reflect that and to clarify that the surfaces pictured were from “soft” landings.
And now there are eight. With Philae’s incredible landing on a comet earlier this week, humans have now done soft landings on eight solar system bodies. And that’s just in the first 57 years of space exploration. How far do you think we’ll reach in the next six decades? Let us know in the comments … if you dare.
More seriously, this amazing composition comes courtesy of two people who generously compiled images from the following missions: Rosetta/Philae (European Space Agency), Hayabusa (Japan Aerospace Exploration Agency), Apollo 17 (NASA), Venera 14 (Soviet Union), the Spirit rover (NASA) and Cassini-Huygens (NASA/ESA). Omitted is NEAR Shoemaker, which landed on Eros in 2001.
Before Philae touched down on Comet 67P/Churyumov–Gerasimenko Wednesday, the NASA Jet Propulsion Laboratory’s Mike Malaska created a cool infographic of nearly every place we’ve lived or visited before then. This week, Michiel Straathof updated the infographic to include 67P (and generously gave us permission to use it.)
And remember that these are just the SURFACES of solar system bodies that we have visited. If you include all of the places that we have flown by or taken pictures from of a distance in space, the count numbers in the dozens — especially when considering prolific imagers such as Voyager 1 and Voyager 2, which flew by multiple planets and moons.
To check out a small sampling of pictures, visit this NASA website that shows some of the best shots we’ve taken in space.
An astronaut retrieves a sample from an asteroid in this artist's conception. Credit: NASA
We’re still a few years away from the cute robots in Moon or Interstellar that help their human explorers. But if we want to build a base off of Earth, robotic intelligence will be essential to lower the cost and pave the way for astronauts, argues Philip Metzger, a former senior research physicist at NASA’s Kennedy Space Center.
In the last of a three-part series on getting a base ready on the moon or an asteroid, Metzger talks about the steps to get robots ready for the work and what barriers are standing in the way of accomplishing this.
UT: A table in your 2012 paper talks about the steps of lunar industry, starting with tele-operation and an “insect-like” robotic intelligence and then progressing through a few steps to “closely supervised autonomy” (mouse-like) and eventually “nearly full autonomy” (monkey-like) and “autonomous robotics” (human-like). What sorts of developments and how much time/resources would it take to progress through these steps?
Most of the advances in robotic artificial intelligence are being made in software, but they also require advances in computing power. We mentioned in the paper that really only “mouse-like” robotics is needed for it to become successful in a near-Earth environment. We will need robots that can pick up a nut and screw it on a bolt without every motion being commanded from Earth. I believe we are on a trajectory to achieve these levels of autonomy already for robotics here on Earth. I am more concerned about developing robots that can be made easily in space without an extensive supply chain. For example, we need to invent a simple way to manufacture functional motors for the robots, minimizing the assembly tasks for robots making the same motors that are in themselves.
It is very difficult to estimate how long this will take. Here are some guiding ideas. First, robotics and manufacturing technologies are already on an explosive growth curve for terrestrial application, so we can ride on the coattails of that growth as we re-purpose the technologies for space. Second, we are not talking about inventing new capabilities. Everything we are talking about doing in space is already being done on Earth. All we need to do is discover what sets of equipment will function together as partial supply chains using space resources. We need to develop a sequence of partial supply chains, each more sophisticated than the last, each one capable of making a significant portion of the mass of the next. It will require innovation, but it is lower-risk innovation because we already have Earth’s more sophisticated industry to copy.
R2 and D2? NASA and General Motors have come together to develop the next generation dexterous humanoid robot. The robots – called Robonaut2 – were designed to use the same tools as humans, which allows them to work safely side-by-side humans on Earth and in space. Credit: NASA
Third, we tend to estimate things will happen faster than they do in the near term, but slower than they do in the long term. Consider how much technology has changed in the past 200 years, and you will agree that it won’t take another 200 years to get this done. I think it will be much less than 100 years. I am betting it will be done within 50 years, and if we try hard we could do it in 20. In fact, if we really wanted to, and if we put up the money, I think we could do it in 10. But I’m telling people 20 to 50 years. Don’t worry if you think that’s too slow, because the fun of doing it can start immediately, and we will be doing really cool things in space long before the supply chain is complete.
UT: Is it really cheaper and scientifically viable to have a robotic fleet of spacecraft than humans, given development costs and the difficulties of making the robots as efficient to do work as humans?
Biological life needs a place like planet Earth. Humans need more than that; we also need a food chain, and in the final analysis we need an entire ecology of networked organisms interdependent on each other. And if we want to be more than hunters and gatherers, then civilization requires even more than that. We require the industrial supply chain: all the tools and machines and energy sources that we have developed over the past 10,000 years.
When we leave Earth, we need to take not just a canister of air to breath to replicate the physical conditions of our planet. We need the benefit of the entire ecosystem and the entire industrial base to support us. So far we have stayed close to Earth so we have never really “cut the surly bonds of Earth.” We take a consumable supply of food and spare parts from Earth with us, and we send up rockets to the space station when we need more. Even schemes to colonize Mars are depending on regular shipments of things from Earth. These are the things that make it expensive to put humans in space.
Robots, on the other hand, can be adapted to living in the space environment with nothing more from Earth. They can become the ecosphere and the supply chain in space that we humans require. Under our guidance, they can transform any environment analogously to how life has transformed the Earth. They can make air, purify water, and build the habitats and landing pads. Then, when we arrive, it will be vastly less expensive, and it will be safer, too. And this will free us up to spend our time in space doing the things that make us uniquely human. In the long term, robots will make space vastly cheaper for humans.
Canada’s Dextre robot (highlight) and NASA’s Robotic Refueling Experiment jointly performed groundbreaking robotics research aboard the ISS in March 2012. Dextre used its hands to grasp specialized work tools on the RRM for experiments to repair and refuel orbiting satellites. Credit: NASA
But yes, in the near-term there are things we can do more affordably in space by skipping development of robotic industry. We can shoot off sortie missions to various places, and when we are done we can zip back home before everyone dies. But that doesn’t fulfill our great potential as a species. It doesn’t take civilization to the next level. It doesn’t enable scientific research with a billion times the budget we have today. It doesn’t save our planet from overuse and industrial pollution. It doesn’t bring all humanity up to the standard of living many of us are enjoying in the west. It doesn’t make our existence safe in the galaxy. It doesn’t terraform new worlds. It doesn’t take us to other stars. All these things will be possible for almost no additional investment once we pay the tiny cost of bootstrapping industry in our solar system. It’s worth the cost.
I know of several other groups also developing 3D printers that could work on the Moon or Mars to print things directly out of regolith. The KSC Swamp Works is pursuing one technological approach and has built a prototype, and Professor Behrokh Khoshnevis at the University of Southern California is pursing another approach and has printed many things already. My friend Jason Dunn who founded Made In Space, which put the 3D printer into the ISS, has another concept they are pursuing. My friends at NASA have told me that this is healthy, having a portfolio of technologies to pursue rather than just one.
To be ready for missions in space you have to do more than test things in a lab. You need to do testing in reduced gravity aircraft to see if the materials like regolith will flow properly, in vacuum chambers to make sure nothing overheats or jams, and in rugged field locations like a desert or on a volcano to check for dust problems or other unexpected effects. After that, you are ready to start designing the actual version that is going into space, to do the final qualification testing where you shake it and bake it half to death, to assemble and test the flight version, and to launch it.
Deputy Program Manager Matthew Napoli examines a 3D printed piece at Marshall Space Flight Center. Image courtesy Made In Space.
So there are years of work ahead before all that is done. NASA’s direction is to put humans on Mars by the mid-2030’s, so we also have time and there is no rush. If we start to bootstrap space industry in the near-Earth region of space in parallel with getting ready for a Mars campaign then we will probably start testing regolith printers at field sites and making them interoperable with other equipment sooner than NASA presently needs them.
UT: What are the main barriers to robotic exploration on the Moon and beyond?
Budget is the only barrier. But taking a step back we might say a lack of vision is the only barrier because if enough of us understand what is now possible in space and how revolutionary it will be for humanity then there will be no lack of budget.
UT: Is there anything else you would like to add that I haven’t brought up yet?
We live in a very exciting time when these possibilities are being opened to us. It is exciting to think about the world our grandchildren will see, and it is exciting to think of what we can do to bring it about.
Whenever I speak on this topic, afterward the young people in the audience come up and start asking what they can do to get involved in space industry. They tell me that this is how they want to spend their lives. It gets that response because it is so compelling, so logical, and so right.
How much would it cost to establish a space base close to Earth, say on the Moon or an asteroid? To find out, Universe Today spoke with Philip Metzger, a former senior research physicist at NASA’s Kennedy Space Center, who has explored this subject extensively on his website and in published papers.
UT: Your 2012 paper specifically talks about how much development is needed on the Moon to make the industry “self-sustaining and expanding”, but left out the cost of getting the technology ready and of their ongoing operation. Why did you leave this assessment until later? How can we get a complete picture of the costs?
PM: As we stated at the start of the paper, our analysis was very crude and was intended only to garner interest in the topic so that others might join us in doing a more complete, more realistic analysis. The interest has grown faster than I expected, so maybe we will start to see these analyses happening now including cost estimates. Previous analyses talked about building entire factories and sending them into space. The main contribution of our initial paper was to point out that there is this bootstrapping strategy that has not been discussed previously, and we argued that it makes more sense. It will result in a much smaller mass of hardware launched into space, and it will allow us to get started right away so that we can figure out how to make the equipment work as we go along.
Moonbase rover concept – could be used for long-term missions (NASA)
Trying to design up front everything in a supply chain for space is impossible. Even if we got the budget for it and gave it a try, we would discover that it wouldn’t work when we sent it into the extraterrestrial environments. There are too many things that could go wrong. Evolving it in stages will allow us to work out the bugs as we develop it in stages. So the paper was arguing for the community to take a look into this new strategy for space industry.
Now, having said that, I can still give you a very crude cost estimate if you want one. Our model shows a total of about 41 tons of hardware being launched to the Moon, but that results in 100,000 tons of hardware when we include what was made there along the way. If 41 tons turns out to be correct, then let’s take 41% of the cost of the International Space Station as a crude estimate, because that has a mass of 100 tons and we can roughly estimate that a ton of space hardware costs about the same in every program. Then let’s multiply by four because it takes four tons of mass launched to low Earth orbit to land one ton on the Moon.
That may be an over-estimate, because the biggest cost of the International Space Station was the labor to design, build, assemble, and test before launch, including the cost of operating the space shuttle fleet. But the hardware for space industry includes many copies of the same parts so design costs should be lower, and since human lives will not be at stake they don’t need to be as reliable. As discussed in the paper, the launch costs will also be much reduced with the new launch systems coming on line.
The International Space Station in March 2009 as seen from the departing STS-119 space shuttle Discovery crew. Credit: NASA/ESA
Furthermore, the cost can be divided by 3.5 according to the crude modeling, because 41 tons is needed only if the industry is making copies of itself as fast as it can. If we slow it down to making just one copy of the industry along the way as it is evolving, then only 12 tons of hardware needs to be sent to the Moon. Now that gives us an estimate of the total cost over the entire bootstrapping period, so if we take 20 or 30 or 40 years to accomplish it, then divide by that amount to get the annual cost. You end up with a number that is a minority fraction of NASA’s annual budget, and a miniscule fraction of the total U.S. federal budget, and even tinier fraction of the US gross domestic product, and an utterly insignificant cost per human being in the developed nations of the Earth.
Even if we are off by a factor of 10 or more, it is something we can afford to start doing today. And this doesn’t account for the economic payback we will be getting while starting space industry. There will be intermediate ways to get a payback, such as refueling communications satellites and enabling new scientific activities. The entire cost needn’t be carried by taxpayers, either. It can be funded in part by commercial interests, and in part by students and others taking part in robotics contests. Perhaps we can arrange shares of ownership in space industry for people who volunteer time developing technologies and doing other tasks like teleoperating robots on the Moon. Call that “telepioneering.”
Perhaps most importantly, the technologies we will be developing – advanced robotics and manufacturing – are the same things we want to be developing here on Earth for the sake of our economy, anyway. So it is a no-brainer to do this! There are also intangible benefits: giving students enthusiasm to excel in their education, focusing the efforts of the maker community to contribute tangibly to our technological and economic growth, and renewing the zeitgeist of our culture. Civilizations fall when they become old and tired, when their enthusiasm is spent and they stop believing in the inherent value of what they do. Do we want a positive, enthusiastic world working together for the greater good? Here it is.
The Japanese Kibo robotic arm on the International Space Station deploys CubeSats during February 2014. The arm was holding a Small Satellite Orbital Deployer to send out the small satellites during Expedition 38. Credit: NASA
UT: We now have smaller computers and the ability to launch CubeSats or smaller accompanying satellites on rocket launches, something that wasn’t available a few decades ago. Does this reduce the costs of sending materials to the Moon for the purposes of what we want to do there?
Most of the papers about starting the space industry are from the 1980’s and 1990’s because that is when most of the investigations were performed, and there hasn’t been funding to continue their work in recent decades. Indeed, changes in technology since then have been game-changing! Back then some studies were saying that a colony would need to support 10,000 humans in space to do manufacturing tasks before it could make a profit and become economically self-sustaining. Now because of the growth of robotics we think we can do it with zero humans, which drastically cuts the cost.
The most complete study of space industry was the 1980 Summer Study at the Ames Research Center. They were the first to discuss the vision of having space industry fully robotic. They estimated mining robots would need to be made with several tons of mass. More recently, we have actually built lunar mining robots at the Swamp Works at the Kennedy Space Center and they are about one tenth of a ton, each. So we have demonstrated a mass reduction of more than 10 times.
But this added sophistication will be harder to manufacture on the Moon. Early generations will not be able to make the lightweight metal alloys or the electronics packages. That will require a more complex supply chain. The early generations of space industry should not aim to make things better; they should aim to make things easier to make. “Appropriate Technology” will be the goal. As the supply chain evolves, eventually it will reach toward the sophistication of Earth. Still, as long as the supply chain is incomplete and we are sending things from Earth, we will be sending the lightest and most sophisticated things we can to be combined with the crude things made in space, and so the advances we’ve made since the 1980’s will indeed reduce the bootstrapping cost.
Vivid Vesta Vista in Vibrant 3 D from NASA’s Dawn Asteroid Orbiter. Vesta is the second most massive asteroid and is 330 miles (530 km) in diameter. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
When NASA’s Dawn spacecraft arrived at Vesta in July 2011, two features immediately jumped out at planetary scientists who had been so eagerly anticipating a good look at the giant asteroid. One was a series of long troughs encircling Vesta’s equator, and the other was the enormous crater at its southern pole. Named Rheasilvia, the centrally-peaked basin spans 500 kilometers in width and it was hypothesized that the impact event that created it was also responsible for the deep Grand Canyon-sized grooves gouging Vesta’s middle.
Now, research led by a Brown University professor and a former graduate student reveal how it all probably happened.
“Vesta got hammered,” said Peter Schultz, professor of earth, environmental, and planetary sciences at Brown and the study’s senior author. “The whole interior was reverberating, and what we see on the surface is the manifestation of what happened in the interior.”
Using a 4-meter-long air-powered cannon at NASA’s Ames Vertical Gun Range, Peter Schultz and Brown graduate Angela Stickle – now a researcher at the Johns Hopkins University Applied Physics Laboratory – recreated cosmic impact events with small pellets fired at softball-sized acrylic spheres at the type of velocities you’d find in space.
The impacts were captured on super-high-speed camera. What Stickle and Schultz saw were stress fractures occurring not only at the points of impact on the acrylic spheres but also at the point directly opposite them, and then rapidly propagating toward the midlines of the spheres… their “equators,” if you will.
Scaled up to Vesta size and composition, these levels of forces would have created precisely the types of deep troughs seen today running askew around Vesta’s midsection.
Watch a million-fps video of a test impact below:
So why is Vesta’s trough belt slanted? According to the researchers’ abstract, “experimental and numerical results reveal that the offset angle is a natural consequence of oblique impacts into a spherical target.” That is, the impactor that struck Vesta’s south pole likely came in at an angle, which made for uneven propagation of stress fracturing outward across the protoplanet (and smashed its south pole so much that scientists had initially said it was “missing!”)
Close-ups of Vesta’s equatorial troughs obtained by Dawn’s framing camera in August and September 2011. (NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA)
That angle of incidence — estimated to be less than 40 degrees — not only left Vesta with a slanted belt of grooves, but also probably kept it from getting blasted apart altogether.
“Vesta was lucky,” said Schultz. “If this collision had been straight on, there would have been one less large asteroid and only a family of fragments left behind.”
Watch a video tour of Vesta made from data acquired by Dawn in 2011 and 2012 below:
The team’s findings will be published in the February 2015 issue of the journal Icarus and are currently available online here (paywall, sorry). Also you can see many more images of Vesta from the Dawn mission here and find out the latest news from the ongoing mission to Ceres on the Dawn Journal.
Building a lunar base might be easier if astronauts could harvest local materials for the construction, and life support in general. Credit: NASA/Pat Rawlings
So can we get off of Earth already and start building bases on the Moon or an asteroid? As highlighted in a recent Office of Science and Technology Policy blog post, one way to do that quickly could be to use resources on site. But how do we even get started? Can we afford to do it now, in this tough economic climate?
Universe Today spoke with Philip Metzger, a former senior research physicist at NASA’s Kennedy Space Center, who has explored this subject extensively on his website and in published papers. He argues that to do space this way would be similar to how the pilgrims explored North America. In the first of a three-part series, he outlines the rationale and the first steps to making it there.
UT: It’s been said that using resources on the Moon, Mars or asteroids will be cheaper than transporting everything from Earth. At the same time, there are inherent startup costs in terms of developing technology to do this extraction and also sending this equipment over there, among other things. How do we reconcile these two realities?
PM: Space industry will have a tremendous payback, but it will be costly to start. Several years ago I was frustrated because I didn’t think that commercial interests alone would be enough to get it fully started within our generation, so I asked the question, can we find an inexpensive way for the governments of the world (or philanthropists or others who may not have an immediate commercial interest) to get it started simply because of the societal benefits it will bring? That’s why my colleagues and I wrote the paper “Affordable Rapid Bootstrapping of Space Industry and Solar System Civilization.”
We are advocating a bootstrapping approach because it helps solve the problem of the high startup cost and it enables humanity to start reaping the benefits quickly, since we need them quickly. A bootstrapping approach works like this: instead of building all the hardware on Earth and sending it into space ready to start manufacturing things, we can send a reduced set of hardware into space and make only a little bit of what we need. We can send the rest of the manufactured parts from Earth and combine them with what we made in space. Over time we keep doing this until we evolve up to a full manufacturing capability in space.
On a clear day, astronauts aboard the ISS can see over 1,000 miles from Havana to Washington D.C. Image Credit: Chris Hadfield / NASA
This is how colonies on Earth built themselves up until eventually they were able to match the industry of their homelands. The pilgrims, for example, didn’t bring entire factories from Europe over on the Mayflower. Now it took hundreds of years to build up American industry, but with robotics and advanced manufacturing and with some intentionality we can get it done much more quickly at still an affordable price. We have done some rudimentary modeling of this bootstrapping approach and it looks as though it would be a small part of our annual space budget and it could establish the industry within just decades.
What I think is even more important than the cost is that with a bootstrapping approach we can get started right away. We don’t need to complete the entire design and development up front. It also spreads the cost over time so the annual expenses are very low. And it allows us time to evolve our strategy, to figure out what works and what will have more immediate economic payback, as we go along. Many people are looking for the immediate ways to get a payback in space, and there are some great ideas and I am sure they will be successful. One example is to set up a mining operation that refuels communication satellites in geosynchronous orbit. These sorts of activities will contribute to, and will benefit from, the effort to start industry in space, and they will generate revenue to fund their portion of the effort.
UT: Why do you feel the Moon is a good spot to start operations? What would be some activities to start with there? How do we move from there into the rest of the solar system?
When my colleagues and I wrote the paper, we were focused on the Moon in part because that was during NASA’s Constellation program to establish a lunar outpost. However, it is equally possible to use near-Earth asteroids to start this space industry, or to use both. In any case, we need to start space industry close to the Earth. That will keep transportation costs low during the startup. It also enables us to work with much shorter time delay in the radio communications, which is important in the early stages before robotics become sufficiently automated. Ideally the industry will be fully automated; we want robots to prepare the way for humans to follow.
The cancelled Constellation Program. Credit: NASA
However, if we think we will need humans during initial start-up of the industry – for example, to fix or troubleshoot broken hardware, or to do complex tasks that robots can’t yet do – then starting near Earth becomes even more important. It turns out that both the Moon and asteroids are excellent places to start industry. We now know that they have abundant water, minerals from which metals can be refined, carbon for making plastics, and so on. I am glad there are companies planning to develop mining in both locations so we can see what works best.
Another reason to start industry close to Earth is so it can have an early economic payback. In the end, when everything including spaceships and refueling depots are made in space by autonomous robotics, then industry becomes self-sustaining and it will pay us back inestimably for no further cost. Getting to that point requires some serious investment, though, and it will be easier to make the investments if we are getting something back. So what kinds of payback can it give us in the near-term? I keep a list of ideas how to make money in space, and there are about 19 items on the list, some crazy and some not so crazy. A few of the serious ideas include: space tourism; making and selling propellants to NASA for exploration and science missions; returning metals like platinum for sale on Earth; and manufacturing spare parts for other activities in space.
Artist’s rendition of a Moon Base. Credit: John Spencer/Space Tourism Society.
Some of the initial things we will do on the Moon or asteroids includes perfecting the low-gravity mining techniques, learning how to make solar cells out of regolith, and learning how to extract useful metals from minerals that would not be considered “ore” here on Earth. All of these are possible and require only modest investment to make them work.
It will take decades of effort to make space industry self-sustaining. Maybe 2 decades if we get started right away and work steadily, or maybe 5 decades if we have a lower level of funding. But if robotics advance as fast as the roboticists are expecting, soon there will be no manufacturing task a robot cannot do. When that day arrives, and we have set up a complete supply chain in space, then it will be an easy thing to send sets of hardware to the main asteroid belt to begin mining and manufacturing where there are billions of times the resources more than what we have on Earth.
Then, the industry could build landing craft to take equipment to the surface of Mars where it can build cities and eventually even terraform the planet. When we have machines that can use local resources to perform work and build copies of themselves, then they can perform the same role on dry worlds that biological life has performed here on our wet Earth. They can transform the environment and become the food chain so those worlds will be places where humanity can work and live. I realize this sounds too ambitious, but 20 to 50 years of technology growth is going to make a huge difference, and we are only talking about manufacturing – not rocket science — and that is something that we are already quite good at here on Earth. With just a little extrapolation into the future it is not a crazy idea.
Artist concept of a Moon base. Credit: NASA/Pat Rawlings.
UT: What are the main pieces of equipment and robotics that we need up there to accomplish these objectives?
PM: There is an interesting open source project developing what they call the “Global Village Construction Set.” It is 50 machines that will be capable of restarting civilization. It includes things like a windmill, a backhoe, and a 3D printer. What we need is the equivalent “Lunar/Asteroid Village Construction Set.”
A study was done by NASA in 1980 to determine what set of machines are needed in factories on the Moon to build 80% of their own parts. The other 20% would need to be supplied constantly from Earth. In our paper we argued that we can start at much less than 80% closure, making it more affordable and allowing us to start today, but the system should evolve until it reaches 100% closure. So the first set of hardware might make crude solar cells, metal, 3D printed metal parts, and rocket propellants.
Having just that will allow us to make a significant mass of the next generation of hardware as well as support the transportation network. Over time, we want to develop an entire supply chain which would be more extensive than just 50 different types of machines. But before we put anything in space we will want to test them in rugged locations here on Earth, and in the process we will discover what set of machines makes the most sense for the first generation. The idea is to learn as we go, so we can get started right away.
Goldstone delay-Doppler images of 2014 SC324 obtained on October 25. The images span an interval of about 45 minutes and show considerable rotation
by this object, which has an irregular and elongated shape. Credit: NASA/JPL
Looks like we dodged a bullet. A bullet-shaped asteroid that is. The 70-meter Goldstone radar dish, part of NASA’s Deep Space Network, grabbed a collage of photos of Earth-approaching asteroid 2014 SC324 during its close flyby last Friday October 24. These are the first-ever photos of the space rock which was discovered September 30 this year by the Mt. Lemmon Survey. The level of detail is amazing considering that the object is only about 197 feet (60-meters) across. You can also see how incredibly fast it’s rotating – about 30-45 minutes for a one spin.
A cropped version of the photo to more clearly see the asteroid’s shape. 2014 SC324 passed just 1.5 lunar distances from Earth last week. Credit: NASA/JPL
In the cropped version, the shape is somewhat clearer with the asteroid appearing some four times longer than wide. 2014 SC324 belongs to the Apollo asteroid class, named for 1862 Apollo discovered in 1932 by German astronomer Karl Reinmuth. Apollo asteroids follow orbits that occasionally cross that of Earth’s, making them a potential threat to our planet. The famed February 15, 2013 Chelyabinsk fireball, with an approximate pre-atmospheric entry size of 59 feet (18-m), belonged to the Apollo class.
Three classes of asteroids that pass near Earth or cross its orbit are named for the first member discovered — Apollo, Aten and Amor. Apollo asteroids like 2014 SC324 routinely cross Earth’s orbit, Atens also cross but have different orbital characteristics and Amors cross Mars’ orbit but miss Earth’s. Credit: ESA
Lance Benner and colleagues at Goldstone also imaged another Apollo asteroid that passed through our neighborhood on October 19 called 2014 SM143. This larger object, estimated at around 650 feet (200-m) across, was discovered with the Pan-STARRS 1 telescope on Mt. Haleakala in Hawaii on September 17. Tell me we’re not some shiny ball on a solar system-sized pool table where the players fortunately miss their shot … most of the time.
Ambition is a collaboration between Platige Image and ESA. Shot on location in Iceland, it is directed by Tomek Bagi?ski and stars Aiden Gillen and Aisling Franciosi. Does Ambition accomplish more in 7 minutes than Gravity did in 90? Consider the abstraction of the Rosetta mission in light of NASA’s ambitions. (Credit: ESA, Illustration- TRR)
NASA has taken on space missions that have taken years to reach their destination; they have more than a dozen ongoing missions throughout the Solar System and have been to comets as well. So why pay any attention to the European Space Agency’s comet mission Rosetta and their new short film, “Ambition”?
‘Ambition’ might accomplish more in 7 minutes than ‘Gravity’ did in 90.
‘Ambition’ is a 7 minute movie created for ESA and Rosetta, shot on location in Iceland, directed by Oscar-winning Tomek Baginski, and stars Aidan Gillen—Littlefinger of ‘Game of Thrones.’ It is an abstraction of the near future where humans have become demigods. An apprentice is working to merge her understanding of existence with her powers to create. And her master steps in to assure she is truly ready to take the next step.
In the reality of today, we struggle to find grounding for the quest and discoveries that make up our lives on a daily basis. Yet, as the Ebola outbreak or the Middle East crisis reminds us, we are far from breaking away. Such events are like the opening scene of ‘Ambition’ when the apprentice’s work explodes in her face.
The ancient Greeks also took great leaps beyond all the surrounding cultures. They imagined themselves as capable of being demigods. Achilles and Heracles were born from their contact with the gods but they remained fallible and mortal.
The Comet Rendezvous and Flyby Mission conceived in one of two Mariner Mark II spacecraft was abandoned by the US Congress. The American led mission would have accomplished the objectives now being completed by the European Rosetta mission. (Photo Credit: NASA)
But consider the abstraction of the Rosetta mission in light of NASA’s ambitions. As an American viewing the European short film, it reminds me that we are not unlike the ancient Greeks. We have seen the heights of our powers and ability to repel and conquer our enemies, and enrich our country. But we stand manifold vulnerable.
In ‘Ambition’ and Rosetta, America can see our European cousins stepping ahead of us. The reality of the Rosetta mission is that a generation ago – 25 years — we had a mission as ambitious called Comet Rendezvous Asteroid Flyby (CRAF). From the minds within NASA and JPL, twin missions were born. They were of the Mariner Mark II spacecraft design for deep space. One was to Saturn and the other – CRAF was to a comet. CRAF was rejected by congress and became an accepted sacrifice by NASA in order to save its twin, the Cassini mission.
The short film ‘Ambition’ and the Rosetta mission is a reminder of what American ambition accomplished in the 60’s – Apollo, and the 70s – the Viking Landers, but then it began to falter in the 80s. The ambition of the Europeans did not lose site of the importance of comets. They are perhaps the ultimate Rosetta stones of our star system. They are unmitigated remnants of what created our planet billions of years ago unlike the asteroids that remained close to the Sun and were altered by its heat and many collisions.
Artist Illustration of the Cassini space probe to Saturn and Titan, a joint NASA, ESA mission. Cassini was the only Mariner Mark II spacecraft completed. (Photo Credit: NASA)
Our cousins picked up a scepter that we dropped and we should take notice that the best that Europe spawned in the last century – the abstract art of Picasso and Stravinsky, rocketry, and jet travel — remains alive today. Europe had the vision to continue a quest to something quite abstract, a comet, while we chose something bigger and more self-evident, Saturn and Titan.
‘Ambition’ shows us the forces at work in and around ESA. They blend the arts with the sciences to bend our minds and force us to imagine what next and why. There have been American epoch films that bend our minds, but yet sometimes it seems we hold back our innate drive to discover and venture out.
NASA recently created a 7 minute film of a harsh reality, the challenge of landing safely on Mars. ESA and Rosetta’s short film reminds us that we are not alone in the quest for knowledge and discovery, both of which set the stage for new growth and invention. America needs to take heed so that we do not wait until we reach the moment when an arrow pierces our heel as with Achilles and we succumb to our challengers.
Here comes another asteroid! 2014 SC324 will miss Earth by 1.5 times the distance to the Moon early Friday afternoon October 24, 2014. Credit: Gianluca Masi / Software Bisque
What a roller coaster week it’s been. If partial eclipses and giant sunspots aren’t your thing, how about a close flyby of an Earth-approaching asteroid? 2014 SC324 was discovered on September 30 this year by the Mt. Lemmon Surveyhigh in the Catalina Mountains north of Tucson, Arizona. Based on brightness, the tumbling rock’s size is estimated at around 197 feet (60-m), on the large side compared to the many small asteroids that whip harmlessly by Earth each year.
Near-Earth asteroid 2014 SC324 caught in the camera on October 23. The telescope tracked on the zippy space rock, causing the stars to trail. Credit: Gianluca Masi
Closest approach happens around 2 p.m. CDT (7 p.m. UT) Friday afternoon when our fast friend misses Earth by just 351,000 miles (565,000 km) or 1.5 times the distance to the Moon. This is a very safe distance, so we can finish up our lunches without a jot of concern. But the asteroid’s combination of size and proximity means amateur astronomers with a 10-inch or larger telescope will be able to track it across the sky beginning tonight (Oct. 23) and continuing through tomorrow night. 2014 SC324 should shine tolerably bright this evening at around magnitude +13.5.
Bright here is something of a euphemism, but when it comes to new Earth-approaching asteroids, this is within range of many amateur instruments. And because 2014 SC324 is “only” a half million miles away tonight, it’s not moving so fast that you can’t plot its arc on a single star chart, spot it and go for a ride.
Simulation based on recent data showing the known asteroids orbiting the Sun
By Friday evening, the new visitor will have faded a bit to magnitude +14. You can create a track for 2014 SC324 by inputting its orbital elements into a variety of astro software programs like MegaStar, the Sky, and Le Ciel. Elements are available via the Minor Planet Center and Horizons. Once saved, the program will make a track of the asteroid’s movement at selected time intervals. Print out the chart and you’re ready for the hunt!
Illustration of small asteroids passing near Earth. Credit: ESA / P. Carril
You can also go to Horizons, ask for a list of positions every 15 minutes for example and then hand plot those positions in right ascension (R.A.) and declination (Dec.) on a star map. This is what I do. I find the the general chunk of sky the asteroid’s passing through, print the map and then mark positions in pencil and connect them all with a line. Now I’ve got a chart I can use at the telescope based on the most current orbit.
Tonight the errant mountain will rumble through Aries the Ram, which is conveniently located in the eastern sky below Andromeda and the Great Square of Pegasus at nightfall.
Finding a dim, fast-moving object is doubtless an exciting challenge, but if you lack the equipment or the weather doesn’t cooperate, you can see the show online courtesy of Italian astrophysicist Gianluca Masi. He’ll stream the close encounter live on his Virtual Telescope Project website beginning at 7 p.m. CDT (midnight UT) tomorrow night October 24-25.
