NEO News is a newsletter about near earth asteroids and related topics. The opinions here are those of the author, David Morrison, and do not represent NASA or any other organization. You may quote or use these comments as long as you note the original source.
NASA FY2014 Budget Request: New Asteroid Initiative
Statement from NASA Administrator Charles Bolden:
We are developing a first-ever mission to identify, capture, and relocate an asteroid. This mission represents an unprecedented technological achievement that will lead to new scientific discoveries and technological capabilities and help protect our home planet. This asteroid initiative brings together the best of NASA’s science, technology, and human exploration efforts to achieve the President’s goal of sending humans to an asteroid by 2025. We will use existing capabilities such as the Orion crew capsule and SLS rocket, and develop new technologies like solar electric propulsion and laser communications – all critical components of deep space exploration.
From Associate Administrator for Human Exploration and Operations William Gerstenmaier:
“The mission to find, capture and redirect an asteroid robotically, and then visit it with astronauts to study it and return samples takes advantage of expertise across all of NASA in an integrated approach to exploration. Along with the scientific research and technology demonstrations happening around the clock on the International Space Station that are teaching us how humans can live and work in space, this mission will give us valuable experience we need in deep space operations to send humans to more distant destinations in the solar system, including Mars. Through the balance of this fiscal year, we will work to define an affordable mission architecture. In Fiscal Year 2014, NASA will begin developing and testing prototype capture mechanisms and concepts for crew interactions with the asteroid.”
From Associate Administrator for Science John Grunsfeld:
“The crucial first step in this endeavor is to enhance our ongoing efforts to identify and characterize near-Earth objects for scientific investigation and to find potentially hazardous asteroids and targets appropriate for capture. The capture mission will be a highly visible and significant collaboration of robotic and human exploration in translunar space.”
From Associate Administrator for Space Technology Michael Gazarik:
“This mission accelerates our technology development activities in high-powered solar electric propulsion. The ambitious mission to rendezvous, capture and redirect a small asteroid to Earth-Moon space could not be accomplished without solar electric propulsion technology. This technology also will support the commercial telecommunications and satellite industries, and is an essential step toward future NASA human and robotic exploration forays into deep space.”
Don Yeomans: Prepared Comments for Hearing on Private and International Efforts to Track and Mitigate Asteroids and Meteors
House Committee on Science and Technology, April 10, 2013.
Excerpts from Prepared statement from Donald K. Yeomans, Manager, NASA Near-Earth Object Program Office, JPL. Full transcript can be found at [http://spaceref.com/news/viewsr.html?pid=43816].
Near-Earth objects, commonly called NEOs, are comets and asteroids that can pass within about 28 million miles of the Earth’s orbit. While icy active comets may occasionally pass close to Earth, it is the difficult-to-find, but far more numerous asteroids that are of most concern in near-Earth space today….While the vast population of near-Earth objects is a relatively recent discovery, they are of utmost importance in the study of the solar system’s origin and our own origins, and they will likely play a major role in the future, providing building materials, water and fuel resources for interplanetary exploration and development. It is ironic that the near- Earth objects that are the easiest to reach for robotic or human exploration, and the easiest to exploit for their mineral and material wealth, are the same objects that represent the most serious potential threats to Earth. While finding them is important for future space resource development, we also need to find them – before they find us.
Discovering and identifying relatively small Earth impactors among the millions of asteroids in the Earth’s neighborhood represents a significant challenge…There are about ten million 20-meter sized asteroids like the one that exploded over central Russia two months ago, and their frequency of collision with the Earth is about once every 100 years, on average…But, the events of February 15, 2013, demonstrate that even extremely improbable events can happen, and that it is prudent to pay attention to the problem of finding and tracking all potentially hazardous near-Earth asteroids.
Spaceguard Survey: When I last had the honor to address this Committee in November 2007, about 80% of the NEOs one kilometer or larger had been discovered and only a few percent of the smaller 140 meter objects. Today, the Spaceguard goal of discovering 90% of the large NEOs has been exceeded and about 25% of the 140 meter or larger sized NEO population has been discovered. Today, the discovery rate of NEOs is about 1000 per year, up 50% since 2007…Fully 96% of all NEOs were discovered by NASA-funded surveys…Thus the near-term risk of an unwarned impact from large asteroids, and hence the majority of the risk from all NEOs, has been reduced by more than 90%. Assuming none are found to be an impact threat, discovering 90% of the 140 meter sized objects will further reduce the total risk to the 99% level. By finding these objects early enough and tracking their motions over the next 100 years, even those rare objects that might be found threatening could be deflected using existing technologies. For example, a spacecraft could purposely ram the asteroid, modifying its orbital velocity by a very small amount, so that over several years its trajectory would be modified and its predicted impact of Earth in the future avoided by a safe margin. The autonomous spacecraft navigation required to effect such a collision was successfully demonstrated in July 2005 when NASA’s Deep Impact spacecraft purposely rammed comet Tempel 1 to better understand the comet’s structure and composition.
There have also been dramatic increases in the rate with which observations have been made to understand the physical nature of these NEOs, their so-called “characterization”… Since 2007 when I last addressed this Committee, there has been a 250% increase in the number of infrared observations of NEOs made at the NASA supported Infrared Telescope Facility in Hawaii. During 2012 alone, the number of radar detections of NEOs at both the Goldstone facility in California and the Arecibo facility in Puerto Rico has tripled compared to the average of the previous ten years… There has also been significant progress within the NEO Action Team associated with the UN Committee on the Peaceful Uses of Outer Space (COPUOS) to encourage and integrate more international efforts for NEO detections, for addressing deflection issues and for establishing protocols to be used by the international community in response to a potential NEO threat.
Possible Next Steps: There is still much work to be done. About 50-100 NEOs larger than one kilometer remain undiscovered, along with about 13,000 NEOs larger than 140 meters and millions of objects larger than about 30 meters in extent – the approximate minimum size for a common stony asteroid to cause significant ground damage.
An important planned future contributor is the Space Surveillance Telescope (SST), a 3.5-meter wide-field telescope that is being developed by MIT’s Lincoln Laboratory for DARPA and the US Air Force. When fully operational in late 2014, this telescope will scan a wide region centered on the equatorial band of the night-time sky. Investigations are ongoing to better understand the efficiency with which this telescope will discover NEOs and what sort of scheduling might be intermingled with its prime mission of manmade space object surveillance to carry out these NEO observations.
The most effective, ground-based NEO detection telescope that is currently in planned development is the Large Synoptic Survey Telescope (LSST), a 8.4-meter aperture, widefield telescope that is planned to begin operations in Chile in the early 2020s. To be funded by the National Science Foundation and a consortia of private and international agencies and universities for a variety of science programs, simulations have suggested that the shared use of LSST could catalog approximately 25% of the 140 meter sized NEOs within 5 years of operations and about 45% in ten years.
If the goal is to complete the survey of 140 meter sized objects more quickly, the 2010 National Research Council report entitled “Defending Planet Earth” indicated that a space-based infrared telescope in either a Venus-like orbit or interior to the Earth on the Sun-Earth line (L1 point) would be far more efficient finding NEOs than would existing, or planned, ground-based optical surveys. For the more numerous population of smaller NEOs that can still do significant ground damage, an infrared telescope at L1 would be well positioned to find those smaller objects making close Earth approaches. A successful space-based IR survey telescope in a Venus-like orbit would be very effective in discovering NEOs further in advance and providing positional observations unavailable from Earth-based telescopes. Together these observations would allow a faster refinement of an asteroid’s orbit so that impact predictions could also be updated more quickly. Hence these space-based observations might provide an early “all clear” and avoid otherwise unnecessary concern and unneeded deflection mission planning or initiation.
[Yeomans then discusses short-term warning systems for small impacts]
Summary: The NASA-supported NEO observations program is proceeding extremely well, and the rate with which NEOs are being discovered and physically characterized is increasing each year. There are viable options for accelerating the current NEO search efficiencies either using next-generation, ground-based optical surveys or the even more efficient space-based infrared surveys. The use of both ground-based and space-based assets would be the most effective option for quickly finding 90% of the NEO population larger than 140 meters. Robust future NEO search programs and the attendant physical characterization efforts could provide a large number of target bodies for scientific study, for future robotic and human exploration and for future resource development. These same surveys could also identify which of the discovered NEOs represent potential future threats and do so with enough time to either deflect the object, or warn of its arrival.