From: Ames Research Center
Posted: Wednesday, April 7, 2004
Following are parts of the testimony presented by astronauts Rusty Schweickart and Ed Lu before the U.S. Senate Subcommittee on Science, Technology, and Space at a hearing April 7, 2004. Schweickart was one of the Apollo astronauts, and Lu recently returned to Earth after a 6-month tour of duty on the International Space Station. Their discussions deal primarily with a proposed demonstration mission to develop technology for deflecting an asteroid. For their full testimony, see the news archive at http://impact.arc,nasa.gov.
Others testifying at the same hearing include Wayne Van Citters, Director of the Division of Astronomical Sciences, National Science Foundation; Lindley Johnson, Program Manager of the NASA NEO Observation Program; Grant Stokes, Associate Head of the Aerospace Division of the MIT Lincoln Laboratory and chair of the recent NASA Science Definition Team on sub-km NEOs; and Michael Griffin, Head of the Space Department of the John Hopkins University Applied Physics Lab.
Testimony of Russell L. Schweickart, Chairman, B612 Foundation, before the Subcommittee on Science, Technology and Space of the Senate Commerce Committee (edited)
7 April 2004
First I'd like to thank you for the invitation to speak with you today about this emerging public policy issue of near Earth objects (NEOs) threatening life on Earth. One might have thought, just a few years ago, that the subject of asteroids was one for space wonks and wanna-be astronauts and astronomers. But today the realization is rapidly dawning on the media and the general public that asteroids are a subject of more than passing interest! More and more people are coming to know that some few of these asteroids do not silently pass the Earth, but indeed crash in, largely unannounced. On the rare occasions when this happens they can wreak havoc of a magnitude unprecedented in human history. At the upper limit impacts by large asteroids have caused global destruction leading to the virtually instantaneous extinction of life for most of the species living at the time. The dinosaurs were momentary witnesses to a billion megaton event of this kind 65 million years ago. At the lower limit of concern, but occurring much more frequently, we are dealing with events with an explosive force of 10-15 megatons. It is worth pointing out, however, that these small, most frequent events are more powerful than the blast from the most powerful nuclear weapon in the current U.S. nuclear arsenal.
Given the extremely low frequency of these natural events in combination with the extremely grave consequences when they occur, we find ourselves challenged to properly place this subject in our normal list of priorities. Inattention to infrequent events, regardless of their impact, is the "default" solution of choice given the crowd of issues continually burning around our feet.
Therefore the Committee is to be congratulated for its foresight and exemplary public service in realizing the importance of dealing with this issue now.
Perhaps the best logic path to bring the Committee to appreciate our recommendations for action is to briefly outline the key realities the founders of the B612 Foundation faced when we first came together back in October 2001. We are primarily a group of technical experts familiar with or working within the fields of space exploration and planetary science. We came together out of a deep concern that the threat to life implied in our knowledge of near Earth asteroids (NEAs) was not resulting in any organized effort to take action to protect the public from this hazard. We came together to explore whether or not something could be done, and if so, whether we could trigger a program to protect the public.
A known threat that can potentially destroy millions of lives AND can be predicted to occur ahead of time, AND prevented, cannot responsibly go unaddressed. This inexorable logic led us to decide to take action and examine whether preventive measures could be taken to mitigate this threat, and if so, what specific course of action we would recommend.
It became immediately clear to us that the combination of advanced propulsion technologies and small space-qualified nuclear reactors, both operating in prototype form already, would be powerful enough, with reasonable future development, to deflect most threatening asteroids away from a collision with the Earth, given a decade or more of advance warning.
Nevertheless we saw two immediate problems.
First we lack the specific knowledge of the characteristics of NEAs necessary to design anything approaching a reliable operational system. We could readily show that the technology would exist within a few years to get to and land on an asteroid. We also determined that after arriving at the asteroid we would have enough propulsive energy available to successfully deflect the asteroid from an Earth impact a decade or so later. What was missing however was knowledge about the structure and characteristics of asteroids detailed enough to enable successful and secure attachment to it.
Second we recognized that before we would be able to gather such detailed information about NEAs there would likely be many public announcements about near misses and possible future impacts with asteroids which would alarm the general public and generate a growing demand for action. We felt strongly that there needed to be some legitimate answer to the inevitable question which will be put to public officials and decision makers, "and what are you doing about this?"
These two considerations led us to the conclusion that the most responsible course of action would be to mount a demonstration mission to a NEA (one of our choosing) which would accomplish two essential tasks; 1) gather critical information on the nature of asteroid structure and surface characteristics, and 2) while there, push on the asteroid enough to slightly change its orbit thereby clearly demonstrating to the public that humanity now has the technology to protect the Earth from this hazard in the future.
We furthermore determined that this demonstration mission could be done with currently emerging capabilities within 10-12 years.
We therefore adopted the goal of "altering the orbit of an asteroid, in a controlled manner, by 2015".
Reflecting the work that we have done to bring this goal to realization, a number of us wrote a descriptive article for Scientific American magazine entitled, The Asteroid Tugboat. Scientific American published it in the November 2003 issue of the magazine. I have provided reprints of this article to the Committee and I would like to submit a copy with this testimony and ask that it be incorporated in the record.
A key to implementing this mission is NASA's Prometheus Program. Shortly after B612 Foundation began work on outlining a mission to explore and deflect an asteroid NASA announced the formation of its Prometheus Program to develop and demonstrate technologies to permit routine human and robotic activity in space "beyond low Earth orbit".
The key technologies which NASA recognized would enable this capability are identical with what we had determined were necessary to demonstrate the capability to land on and deflect a near Earth asteroid, i.e., high performance electric propulsion systems and the space nuclear electric power systems to power them. Shortly after announcing the Prometheus Program NASA announced the Jupiter Icy Moons Orbiter (JIMO) mission complete with schematic representations of the spacecraft. Integral to the design of this mission were the very high performance engines and space nuclear power system which would be necessary to enable our B612 mission. We therefore adopted, as an explicit element of our design, the JIMO/Prometheus capabilities, recognizing that this was the most likely path to meeting the demonstration goal that we had set.
Mounting a mission to assure the public that when we discover an asteroid "with our name on it" we can deflect it from a life threatening impact on Earth does not require the development of additional new technologies. The key capabilities required are already "in the pipeline" of the existing Prometheus Program. No new NASA money is required, nor is a change in NASA's mission called for. What is required is that the B612 mission be incorporated within the Prometheus Programä a matter of policy.
Indeed, if one examines the technical requirements associated with the B612 mission, one sees not only a mission ideally suited to demonstrating the Prometheus technology, but a mission notably less demanding than the currently planned JIMO mission. One could then quite easily consider the B612 mission as either a follow-on or a precursor to the JIMO mission, depending on NASA's technical judgment as to where it fits most logically in their mission model.
While many lives are lost every year in natural disasters of one kind or another, there are few natural disasters that can reliably be predicted, much less prevented. Throughout human experience we have been faced with comforting and compensating the devastated after the disaster is over. With near Earth asteroid impacts, however, we are confronted with a massive natural disaster that can be both predicted AND prevented, and the public will come to understand that this is the case.
Given the justifiable public expectation of being protected from both natural and manmade disasters it is incumbent on us to address this known threat responsibly. We therefore make the following specific recommendations:
1) We call on the Congress to task NASA with increasing the capability of the current Spaceguard Survey consistent with the recommendations of the recent NASA Near-Earth Object Science Definition Team report.
2) We call on Congress to direct NASA to incorporate the B612 mission goal of demonstrating the capability of landing on, exploring, and deflecting an asteroid as part of its Prometheus Program.
3) We call on Congress to request that OSTP initiate a high level study to develop a US Government policy for both national and international response to the deflection of near Earth asteroids.
Testimony of Edward Lu, B612 Foundation, before the Subcommittee on Science, Technology and Space of the Senate Commerce Committee (edited)
7 April 2004
Thank you for the opportunity today to discuss a bold new proposal to demonstrate altering the orbit of an asteroid. I represent the B612 foundation, a group of astronomers, engineers, and astronauts, concerned about the issue of asteroid impacts. Recent developments have now given us the potential to defend the Earth against these natural disasters. To develop this capability we have proposed a spacecraft mission to significantly alter the orbit of an asteroid in a controlled manner by 2015.
Why move an asteroid? There is a 10 percent chance that during our lifetimes there will be a 70 meter asteroid that impacts Earth with energy 10 megatons (roughly equivalent to 700 simultaneous Hiroshima sized bombs). There is even a very remote one in 50,000 chance that you and I and everyone we know, along with most of humanity and human civilization, will perish together with the impact of a much larger kilometer or more sized asteroid. We now have the potential to change these odds.
There are many unknowns surrounding how to go about deflecting an asteroid, but the surest way to learn about both asteroids themselves as well as the mechanics of moving them is to actually try a demonstration mission. The first attempt to deflect an asteroid should not be when it counts for real, because there are no doubt many surprises in store as we learn how to manipulate asteroids.
Why by 2015? The time to test, learn, and experiment is now. A number of recent developments in space nuclear power and high efficiency propulsion have made this goal feasible. The goal of 2015 is challenging, but doable, and will serve to focus the development efforts.
How big of an asteroid are we proposing to move? The demonstration asteroid should be large enough to represent a real risk, and the technology used should be scaleable in the future to larger asteroids. We are suggesting picking an asteroid of about 200 meters. A 200 meter asteroid is capable of penetrating the atmosphere and striking the ground with an energy of 600 megatons. Should it land in the ocean (as is likely), it will create an enormous tsunami that could destroy coastal cities. Asteroids of about 150 meters and larger are thought to be comprised of loose conglomerations of pieces, or rubble piles, while smaller asteroids are often single large rocks. The techniques we test on a 200 meter asteroid should therefore also be applicable to larger asteroids.
What does "significantly alter the orbit" mean? If proposed asteroid searches are enacted, we expect to have decades or more of warning before an impact. Given this amount of warning, to prevent an impact only requires that the orbital velocity of an asteroid be altered by a small amount, less than of order 1 cm/sec, or about .02 MPH. This is a tiny velocity increment, considering that the orbital speeds of asteroids are of order 70,000 MPH. However, this is still a very difficult task since the mass of a 200 meter asteroid is of order 10 million tons.
Why does the asteroid need to be moved in a "controlled manner"? If the asteroid is not deflected in a controlled manner, we risk simply making the problem worse. Nuclear explosives for example risk breaking up the asteroid into pieces, thus turning a speeding bullet into a shotgun blast of smaller but still possibly deadly fragments. Explosions also have the drawback that we cannot accurately predict the resultant velocity of the asteroid - not a good situation when trying to avert a catastrophe. Conversely, moving an asteroid in a controlled fashion also opens up the possibility of using the same technology to manipulate other asteroids for the purposes of resource utilization.
How can this be accomplished? This mission is well beyond the capability of conventional chemically powered spacecraft. We are proposing a nuclear powered spacecraft using high efficiency propulsion (ion or plasma engines). Such propulsion packages are currently already under development at NASA as part of the Prometheus Project. In fact, the power and thrust requirements are very similar to the Jupiter Icy Moons Orbiter spacecraft, currently planned for launch around 2012. The B612 spacecraft would fly to, rendezvous with, and attach to a suitably chosen target asteroid (there are many candidate asteroids which are known to be nowhere near a collision course with Earth). By continuously thrusting, the spacecraft would slowly alter the velocity of the asteroid by a fraction of a cm/sec - enough to be clearly measurable from Earth.
What will we learn from this? It is important to remember that this mission is merely a first attempt to learn more about the mechanics of asteroid deflection. There are a number of technical complications, as well as many unknowns about the structure and composition of asteroids. However, the way to make progress is to build, fly, and test. Much of what we will learn is generic to many proposed asteroid deflection schemes, with the added benefit of being able to answer important scientific questions about asteroids themselves. The best way to learn about asteroids is to go there.
NEO News (now in its tenth year of distribution) is an informal compilation of news and opinion dealing with Near Earth Objects (NEOs) and their impacts. These opinions are the responsibility of the individual authors and do not represent the positions of NASA, the International Astronomical Union, or any other organization. To subscribe (or unsubscribe) contact email@example.com. For additional information, please see the website http://impact.arc.nasa.gov. If anyone wishes to copy or redistribute original material from these notes, fully or in part, please include this disclaimer.
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