[meteorite-list] NASA's Near-Earth Object Report to Congress

From: E.P. Grondine <epgrondine_at_meteoritecentral.com>
Date: Mon, 12 Mar 2007 13:37:00 -0700 (PDT)
Message-ID: <427927.33005.qm_at_web36908.mail.mud.yahoo.com>

Hi Ron, all -

I attended the Planetary Defense Conference last week
and watched as Morrison et al. asserted yet once again
that comets apprise only 1% of the impact hazard on
the basis of absolutely no evidence at all other than
their own wishful thinking.

I certainly hope NASA has something in place to track
the fragments of Comet Schwassmann Wachmann 3 on their
passages in 2011, 2017, and 2022.

Thanks for your post on the report.

good hunting,
Ed


--- Ron Baalke <baalke at zagami.jpl.nasa.gov> wrote:

>
> http://neo.jpl.nasa.gov/neo/report2007.html
>
> Near-Earth Object
> Survey and Defintion
> Analysis of Alternvatives
>
> Report to Congress
> March 2007
>
> Note: The full report is available here (PDF -
> 790K):
>
>
http://www.nasa.gov/pdf/171331main_NEO_report_march07.pdf
>
> SUMMARY
>
> Section 321 of the NASA Authorization Act of 2005
> (Public Law No.
> 109-155), also known as the George E. Brown, Jr.
> Near-Earth Object
> Survey Act, directs the NASA Administrator to
> transmit an initial report
> to Congress not later than one year after the date
> of enactment that
> provides: (1) an analysis of possible alternatives
> that NASA may employ
> to carry out the survey program of near-Earth
> Objects (NEO), including
> ground- based and space-based alternatives with
> technical descriptions;
> (2) a recommended option and proposed budget to
> carry out the survey
> program pursuant to the recommended option; and (3)
> an analysis of
> possible alternatives that NASA could employ to
> divert an object on a
> likely collision course with Earth.
>
> The objectives of the George E. Brown, Jr. NEO
> Survey Program are to
> detect, track, catalogue, and characterize the
> physical characteristics
> of NEOs equal to or larger than 140 meters in
> diameter with a perihelion
> distance of less than 1.3 AU (Astronomical Units)
> from the Sun,
> achieving 90 percent completion of the survey within
> 15 years after
> enactment of the NASA Authorization Act of 2005. The
> Act was signed into
> law by President Bush on December 30, 2005.
>
> A study team, led by NASA's Office of Program
> Analysis and Evaluation
> (PA&E), conducted the analysis of alternatives with
> inputs from several
> other U.S. government agencies, international
> organizations, and
> representatives of private organizations. The team
> developed a range of
> possible options from public and private sources and
> then analyzed their
> capabilities and levels of performance including
> development schedules
> and technical risks.
>
> Key Findings for the Survey Program:
>
> * The goal of the Survey Program should be
> modified to detect,
> track, catalogue, and characterize, by the end
> of 2020, 90 percent
> of all Potentially Hazardous Objects (PHOs)
> greater than 140
> meters whose orbits pass within 0.05 AU of the
> Earth's orbit (as
> opposed to surveying for all NEOs).
>
> * The Agency could achieve the specified goal of
> surveying for 90
> percent of the potentially hazardous NEOs by
> the end of 2020 by
> partnering with other government agencies on
> potential future
> optical ground-based observatories and
> building a dedicated NEO
> survey asset assuming the partners' potential
> ground assets come
> online by 2010 and 2014, and a dedicated asset
> by 2015.
>
> * Together, the two observatories potentially to
> be developed by
> other government agencies could complete 83
> percent of the survey
> by 2020 if observing time at these
> observatories is shared with
> NASA's NEO Survey Program.
>
> * New space-based infrared systems, combined
> with shared
> ground-based assets, could reduce the overall
> time to reach the 90
> percent goal by at least three years. Space
> systems have
> additional benefits as well as costs and risks
> compared to
> ground-based alternatives.
>
> * Radar systems cannot contribute to the search
> for potentially
> hazardous objects, but may be used to rapidly
> refine tracking and
> to determine object sizes for a few NEOs of
> potentially high
> interest. Existing radar systems are currently
> oversubscribed by
> other missions.
>
> * Determining a NEO's mass and orbit is required
> to determine
> whether it represents a potential threat and
> to provide required
> information for most alternatives to mitigate
> such a threat.
> Beyond these parameters, characterization
> requirements and
> capabilities are tied directly to the
> mitigation strategy selected.
>
> Key Findings for Diverting a Potentially Hazardous
> Object (PHO):
>
> The study team assessed a series of approaches that
> could be used to
> divert a NEO potentially on a collision course with
> Earth. Nuclear
> explosives, as well as non-nuclear options, were
> assessed.
>
> * Nuclear standoff explosions are assessed to be
> 10-100 times more
> effective than the non-nuclear alternatives
> analyzed in this
> study. Other techniques involving the surface
> or subsurface use of
> nuclear explosives may be more efficient, but
> they run an
> increased risk of fracturing the target NEO.
> They also carry
> higher development and operations risks.
>
> * Non-nuclear kinetic impactors are the most
> mature approach and
> could be used in some deflection/mitigation
> scenarios, especially
> for NEOs that consist of a single small, solid
> body.
>
> * "Slow push" mitigation techniques are the most
> expensive, have the
> lowest level of technical readiness, and their
> ability to both
> travel to and divert a threatening NEO would
> be limited unless
> mission durations of many years to decades are
> possible.
>
> * 30-80 percent of potentially hazardous NEOs
> are in orbits that are
> beyond the capability of current or planned
> launch systems.
> Therefore, planetary gravity assist swingby
> trajectories or
> on-orbit assembly of modular propulsion
> systems may be needed to
> augment launch vehicle performance, if these
> objects need to be
> deflected.
>
> Alternatives Considered to Detect, Track,
> Characterize, and
> Deflect/Mitigate NEOs
>
> The following tables provide a summary of the
> options considered.
> Technical descriptions of each option, as well as
> other combinations of
> alternatives, can be found in subsequent sections of
> this report. For
> each option, Table 1 shows the percentage of PHOs
> that would be found by
> the survey by the end of 2020 and the year each
> option would achieve 90
> percent completion, starting with the option of
> sharing the use of
> potential ground-based observatories, which will be
> referred to as the
> "Reference" architecture through the rest of this
> document. Details
> regarding the availability of assets for each option
> are also found in
> subsequent sections. Table 1 shows that individually
> each of the first
> three options fall short of meeting the
> Congressional goal. As shown in
> the last line of Table 1, the minimum survey
> architecture that achieves
> the goal would be a combination of the shared
> ground-based assets plus
> one of two dedicated asset options.
>
> Table 1. Detection and Tracking Capability Options &
> Summary Results
>
> Table 2. Characterization Options
>
> Table 3. Impulsive Deflection/Mitigation Options
>
> Table 4. Slow Push Deflection/Mitigation Options
>
> Recommended Survey Program
>
> Currently, NASA carries out the "Spaceguard Survey"
> to find NEOs greater
> than 1 kilometer in diameter, and this program is
> currently budgeted at
> $4.1 million per year for FY 2006 through FY 2012.
> We also have
> benefited from knowledge gained in our Discovery
> space mission series,
> such as the Near Earth Asteroid Rendezvous (NEAR),
> Deep Impact, and
> Stardust missions that have expanded our knowledge
> of near-Earth
> asteroids and comets. Participation by NASA in
> international
> collaborations such as Japan's Hayabusa mission to
> the NEO "Itokawa"
> also greatly benefited our understanding of these
> objects. NASA's Dawn
> mission, expected to launch in June 2007, will
> increase our
> understanding of the two largest known main belt
> asteroids, Ceres and
> Vesta, between the planets Mars and Jupiter. NASA
> conducts survey
> programs on many celestial objects - the existing
> Spaceguard program for
> NEOs, surveys for Kuiper Belt Objects, the search
> for extra-solar
> planets, and other objects of interest such as black
> holes to understand
> the origins of our universe. Our Discovery mission
> series in planetary
> science may offer additional opportunities in the
> future beyond our
> current survey efforts.
>
> NASA recommends that the program continue as
> currently planned, and we
> will also take advantage of opportunities using
> potential dual-use
> telescopes and spacecraft - and partner with other
> agencies as feasible
> - to attempt to achieve the legislated goal within
> 15 years. However,
> due to current budget constraints, NASA cannot
> initiate a new program at
> this time.
>
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Received on Mon 12 Mar 2007 04:37:00 PM PDT