[FPSPACE] FW: NEO News (06/05/07) Reactions to NASA NEO Report
epgrondine at hotmail.com
Tue Jun 5 20:13:05 EDT 2007
Hi Larry, all -
This would better be entitled "Morrison's Take on Reactions to the NASA NEO
Chapman neglects to mention that using non-nuclear charge methods requires
the earliest possible detection, as well as good estimates of porosity and
beta. Getting all of these will require the expenditure of funds.
China has its policy for dealing with potential impactors, and Russia has
Speaking about academic referees and formal publication, have I mentioned
before that I am pretty bitter about Benny selling out cometary impact for
Morrison's silence on global warming scepticism? Any 100 meter object
hitting soon is likely to be a dead comet fragment, and damned difficult to
spot from the ground.
Man and Impact in the Americas
>From: "LARRY KLAES" <ljk4 at msn.com>
>To: fpspace at friends-partners.org
>Subject: [FPSPACE] FW: NEO News (06/05/07) Reactions to NASA NEO Report
>Date: Tue, 05 Jun 2007 14:11:23 -0400
> >From: David Morrison <dmorrison at arc.nasa.gov>
> >To: David Morrison <dmorrison at arc.nasa.gov>
> >Subject: NEO News (06/05/07) Reactions to NASA NEO Report
> >Date: Tue, 5 Jun 2007 10:02:32 -0700
> >NEO News (06/05/07) Reactions to NASA NEO Report
> >As reported here previously, in March 2007 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
> >Study: Final Report, which can be downloaded at
> >several members of the NEO community have expressed concerns about this
> >Report. The most extensive critique is by Clark Chapman, posted May 2 on
> >his website at http://www.boulder.swri.edu/clark/frep7crt.doc. Very
> >briefly, some of the concerns raised by Chapman and others are the
> >1. As presented, neither the Executive Summary nor the full Report
> >provides "a recommended option and proposed budget" for a new deep survey
> >for NEAs larger than 140 m, as originally requested by Congress. The
> >includes a high estimate of the cost of such a survey and 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
> >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
> >so. These judgments are further clouded by the fact that we are unlikely
> >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. The Report also contains
> >unrealistic expectations about amateur astronomers' ability to follow-up
> >new deep surveys, which will be finding NEAs that are mostly too faint to
> >be reached with amateur telescopes. (Note: In a 2-page posted addendum,
> >Report authors note that their cost numbers are to be used for comparison
> >only and are not necessarily indicative of real anticipated costs.)
> >2. The Report recommends that nuclear explosions (surface or stand-off)
> >the technology of choice for deflecting NEAs, based on current
> >This conclusion follows from (1) an adopted metric for comparing
> >techniques that is based on maximum force, irrespective of the target
> >asteroid's size, composition, or orbit, and (2) a conclusion that nuclear
> >deflection, although untested, is more technologically mature than
> >ballistic defection or the slow-pull "gravity tractor," both of which are
> >based on some flight experience. In part this issue reflects different
> >assumptions made -- the NASA Report focuses on the very rare large
> >(1 km NEAs), while the critics emphasize the need to defend against much
> >more frequent (and therefore more likely) NEAs in the 100-200 m size
> >which can be deflected relatively easily with non-nuclear options.
> >3. The Report makes confusing recommendations concerning the information
> >needed to characterize NEAs. On the one hand, it concludes that we
> >know enough to select a deflection technology (namely nuclear, see 2
> >above), and recommends that further characterization missions are needed
> >only for NEAs that have already been determined to be on a collision
> >course. Elsewhere, however, it suggests several expensive
> >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.
> >These issues are also reflected in the following news article by Jeff
> >Hecht, published in New Scientist. Meanwhile, discussions are underway
> >between NASA Headquarters and members of the science community to
> >investigate points of difference and lead toward a revised document that
> >achieves a consensus, at least on the technical issues.
> >David Morrison
> >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
> >impacts, critics say. They say the vast majority of impacts would be
> >relatively small asteroids that could be found several decades before
> >would hit Earth, allowing gentle techniques such as gravity tractors to
> >used to deflect them.
> >A NASA working document on ways to find and deflect celestial objects
> >might threaten Earth is deeply flawed in ways that exaggerate the cost
> >difficulty of the programme, critics say.
> >In December 2005, the US Congress gave NASA one year to submit plans for
> >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
> >smaller asteroids, saying flatly, "due to current budget constraints,
> >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
> >was circulated only to study group members and labelled "final report" -
> >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
> >-- 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
> >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,
> >Clark Chapman of the Southwest Research Institute in Boulder, Colorado,
> >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
> >asteroid risk. Chapman says the six potential threats studied in the
> >"are not representative" because they are extreme cases -- including a
> >1-kilometre-wide asteroid and a long-period comet discovered less than
> >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
> >off course using the craft's own gravity, or space tugs, which could
> >push the space rocks into safer orbits.
> >That focus on extreme risks tilted the scales toward deflection
> >that use nuclear explosions - either on the asteroids themselves or
> >to push them away from Earth. The study's approach was that "the bigger
> >bang is better", says Schweickart.
> >But he says explosions are not as precise as the gentler techniques
> >they would scatter the asteroids or resulting debris into new orbits
> >the Sun that could take them through points called "keyholes", narrow
> >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:
> >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
> >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.
> >NEO News (now in its thirteenth year of distribution) is an informal
> >compilation of news and opinion dealing with Near Earth Objects (NEOs)
> >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 dmorrison at arc.nasa.gov. For additional information,
> >please see the website http://impact.arc.nasa.gov. If anyone wishes to
> >or redistribute original material from these notes, fully or in part,
> >please include this disclaimer.
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