HOUSE HEARING REQUESTED ON NASA NEO SURVEY PLANS A request for a hearing in the U.S. House of Representatives Subcommittee on Space & Aeronautics dealing with NEO surveys and related issues has been made by Dana Rohrabacher, a former chair of this subcommittee, as described in the following letter: From: Hon. Dana Rohrabacher, June 20, 2007
To: Hon. Mark Udall
Chairman, Subcommittee on Space & Aeronautics
Committee on Science and Technology
Dear Mr. Chairman: Near Earth Objects (NEOs) including asteroids and comets are often ignored, yet pose a significant threat to our planet. According to a March 2007 NASA report entitled "Near Earth Object Survey and Deflection Analysis of Alternatives," NASA predicts that there are 20,000 objects, each with the potential energy of 100 megatons of TNT or more, that can be considered "potentially dangerous objects." A 100 megaton collision event is predicted to cause a minimum of 50,000 fatalities. At this time our ability to discover and track such objects is woefully inadequate. NASA's current program, known as Spaceguard, has a goal of discovering 90% of NEOs with a 75,000 megaton potential (estimated to cause more than a billion fatalities). If this program is successful, it is estimated that only 35% of the 100 megaton objects will be found. As a result in 2005 I sponsored H.R. 1022, the "George E. Brown Jr. Near-Earth Object Survey Act" which would substantially increase the program by requiring 90% of NEOs 140 meters and larger be cataloged within 15 years. The bill was passed as part of the 2005 NASA Authorization Act. However, in a hearing earlier this year NASA Administrator Michael Griffin testified that while he is concerned about the situation, NASA has no funds available to carry out a more extensive program than Spaceguard. In addition, the Arecibo Radio Telescope, a key resource needed to track NEOs, is on schedule to be shut down by 2011. Taking the aforementioned factors into consideration, I respectfully request the Space and Aeronautics Subcommittee convene a hearing for the following purposes: - To review the status of the Spaceguard program in terms of its ability to meet the goals of the Survey Act, - To explore the impact the closing of Arecibo will have on current and future NEO programs, - To ascertain what other resources may be brought to bear to achieve the object of the Survey Act, - To determine future actions necessary to implement the Survey Act. Thank you for your consideration of this request and you personal attention to this matter. Sincerely, Dana Rohrabacher CC: Congressman Ralph Hall,
Congressman Bart Gordon,
Congressman Tom Feeney. ============================== STATUS OF THE NASA NEO REPORT As reported here in the May 10 news note, NASA published a short version (Executive Summary) of its report to Congress on strategies for dealing with the NEA impact threat. More recently, NASA Headquarters has released the full 271-page text of its 2006 Near-Earth Object Survey and Deflection Study: Final Report, which can be downloaded at http://www.hq.nasa.gov/office/pao/FOIA/NEO_Analysis_Doc.pdf. Subsequently, several members of the NEO community (Clark Chapman and Rusty Schweickart in particular) have posted concerns about this Report. Very briefly, some of the issues are the following: 1. As presented, the Report does not provide "a recommended option and proposed budget" for a new deep survey for NEAs larger than 140 m, as originally requested by Congress. The Report includes several options, with estimated costs of roughly a billion dollars over the next 11 years. Because of the high costs, the Report concludes that NASA cannot recommend a program at this time because it lacks the funding to implement it. Specifically, the Report concludes that the combination of ground-based surveys using the new LSST and Pan-STARS survey systems are not by themselves able to meet the Congressional requirements by 2020, although the astronomers building these two systems think that they can do so. These judgments are further clouded by the fact that we are unlikely to be able to assess the capability of any specific survey system until we actually collect data on the numbers of NEAs down to 140 m size. For comparison, when we began the current Spaceguard Survey we thought there were 2000 NEAs larger than 1 km, while the survey data themselves subsequently showed that there are only 1100. (Note: In a 2-page posted addendum, the Report authors note that their cost numbers are to be used for comparison only and are not necessarily indicative of real anticipated costs. Don Yeomans, a member of the Report team, also provided the following comments: According to the LSST team, the ability of LSST alone to meet the Congressional mandate may be enabled by revising their observing strategy, which included taking 15% of the time that was once devoted to other LSST science efforts. This option was not offered by LSST until after the report was complete. Additionally, the availability of LSST and PanSTARRS data from multiple bands was not considered by the NASA Report due to uncertainties, both in the detection rate and filter sensitivity. This added a level of conservatism to the survey performance estimates found in the Report. ) 2. The Report recommends that nuclear explosions (surface or stand-off) are the technology of choice for deflecting NEAs, based on current technology. This conclusion follows from its focus on NEAs larger than 140 m diameter, and an adopted metric for comparing deflection techniques that is based on maximum force, irrespective of the target asteroid's size or composition. In addition, the authors utilized non-public data on the nuclear technique to conclude that nuclear deflection is more technologically mature than ballistic defection or the slow-pull "gravity tractor." 3. The Reports message concerning the information needed to characterize NEAs is unclear. On the one hand, it concludes that we already know enough to select a deflection technology (namely nuclear, see 2 above), and recommends that further characterization missions are required only for NEAs that have already been determined to be on a collision course. Elsewhere, however, it suggests several characterization options that involve sending missions to investigate 8 different asteroid "types". There is also some confusion about what can be done with ground-based telescopes, especially concerning the roles of thermal radiometry, polarimetry, and radar observations. =============================== RECENT PRESS COVERAGE OF THE NASA NEO REPORT NASA ANALYSIS OF ASTEROID RISK DEEPLY FLAWED, CRITICS SAY
By Jeff Hecht, NewScientist.com, 21 May 2007 NASA's analysis of how to find and deflect space rocks that could strike Earth focuses on extreme cases representing only 5% of the potential impacts, critics say. They say the vast majority of impacts would be relatively small asteroids that could be found several decades before they would hit Earth, allowing gentle techniques such as gravity tractors to be used to deflect them. A NASA working document on ways to find and deflect celestial objects that might threaten Earth is deeply flawed in ways that exaggerate the cost and difficulty of the programme, critics say. In December 2005, the US Congress gave NASA one year to submit plans for a survey that would catalog 90% of all potentially hazardous near-Earth objects -- spanning at least 140 metres across -- by the end of 2020. In March 2007, the agency delivered to Congress only a sketchy 27-page report that lacked any detailed analysis, a budget or an implementation plan. It recommends continuing NASA's annual $4.1 million search for asteroids down to 1 kilometre across. But it does not address searches for smaller asteroids, saying flatly, "due to current budget constraints, NASA cannot initiate a new program at this time". Congress was not pleased with the conclusion. Bart Gordon, chair of the House of Representatives' Committee on Science and Technology, said the report did not offer "a credible plan" and vowed to push NASA towards "a more responsive approach". Critics also blasted NASA for failing to publish the longer analysis that led to the report. That analysis, which took the form of a 271-page report, was circulated only to study group members and labelled "final report" - a mistake a NASA spokesman blamed on "stupidity". The spokesman also said NASA had decided "a short, concise report would be more helpful" than a detailed one, and that the agency is waiting for direction -- and a budget -- from Congress and the Administration. NASA has now posted the document (PDF), with a list of errata, on its Freedom of Information Act (FOIA) site. But a copy (23 MB PDF) was earlier posted on the web site of the B612 Foundation, a group of asteroid researchers chaired by former astronaut Rusty Schweickart. Dated 28 December 2006, the long report includes a "fairly good" analysis of the requirements of hunting down asteroids as small as 140 metres, says Clark Chapman of the Southwest Research Institute in Boulder, Colorado, US. It projects costs of $820 million for a survey using ground-based instruments, or $1.0 to $1.3 billion using a dedicated infrared telescope in an orbit near Venus, which could reach the survey goal three years faster and would be more sensitive. But Chapman and others are extremely critical of the document's analysis of asteroid risk. Chapman says the six potential threats studied in the report "are not representative" because they are extreme cases -- including a 1-kilometre-wide asteroid and a long-period comet discovered less than two years before impact. "They didn't study the case of a multi-decade warning of a 100-metre object," he says. Small objects of that scale account for some 95% of potential impacts and could be deflected over long periods of time using gravity tractors - spacecraft that fly next to the asteroids and nudge them off course using the craft's own gravity, or space tugs, which could gently push the space rocks into safer orbits. That focus on extreme risks tilted the scales toward deflection techniques that use nuclear explosions - either on the asteroids themselves or nearby to push them away from Earth. The study's approach was that "the bigger the bang is better", says Schweickart. But he says explosions are not as precise as the gentler techniques because they would scatter the asteroids or resulting debris into new orbits around the Sun that could take them through points called "keyholes", narrow zones where the slight changes in the balance of forces could put them on a collision course with the Earth. "If you just shove it out there to miss the Earth, you can't tell that you haven't put it into another return keyhole," Schweickart told New Scientist. Chapman points to other potential problems with nuclear weapons: "existing international treaties about bombs in space and the potential dangers of maintaining and launching nuclear weapons." The analysis also misunderstands the requirements for a gravity tractor, Schweickart says. He told the study panel that gravity tractors could reach their targets using ion propulsion, such as that used in the successful $147 million Deep Space 1 mission. But the NASA panel instead assumed a gravity tractor would require a $10 billion development of an electric propulsion system based on a space nuclear reactor, similar to NASA's now-cancelled Project Prometheus. NASA says administrator Mike Griffin has been talking with Chapman and Schweickart about their criticisms. --------------------------- NASA ASTEROID REPORT: PICKING OVER THE BONES OF CONTENTION Leonard David, Livescience Blogs, June 19 2007 That NASA Near Earth Object (NEO) study for Congress continues to spark heated debate. A high-level meeting about the report lasted nearly two-and-a-half hours yesterday, June 18, at NASA Headquarters in Washington, D.C. The face-to-face face-off involved the space agency's Office of Program Analysis and Evaluation, as well as former astronauts, Russell Schweickart and Tom Jones, as well as planetary scientist and asteroid specialist, Clark Chapman. NASA was represented by about a dozen individuals, including several technical specialists that took part in the NEO assessment. In a communique to me about the get-together, Chapman rates the NASA meeting as a "sad day" for those hoping to move constructively toward systematic thought on how best to deal with the potential hazard of a dangerous space rock smacking into Earth. "From my perspective, the meeting was very disappointing," Chapman notes. Former Apollo astronaut, Schweickart, had previously tagged the NASA report "flawed" as you can read here at: http://www.space.com/adastra/070527_isdc_asteroids.html One particular area of contention, among several issues, is NASA's backing for standoff nuclear deflection of a NEO, with the space agency report viewing it as an effective way to thwart an incoming asteroid with Earth's name on it. That approach is deemed a very poor idea in almost all cases, Chapman relates. Turns out, however, the NASA NEO study group had received secret input that can't be discussed, making the nuclear option doable, the NASA report relates, for deflecting even the smallest NEOs. Chapman reports that it appears the NASA NEO study was reviewed by the White House and other federal agencies, including the Departments of Defense and Energy. At the meeting, it was acknowledged that several bone of contention issues brought up about the NEO report by Schweickart and Chapman did deserve future study. However, those responsible for the report argued that these were not "mistakes". Chapman was invited by a NASA executive at the meeting to submit his recommended modifications to the report with the promise that the red-lined document would be given to NASA chief, Mike Griffin. Griffin had earlier promised Chapman that if consensus were reached at the meeting about serious errors in the NEO report to Congress, then the study would be modified to set the record straight. In the post-meeting view of Chapman, there are serious matters about the NASA NEO appraisal that urgently deserve study and modification to better reflect "technical realities as they are now understood." |
