[meteorite-list] New Website Tool Now Available For Identifying Mission-Accessible Near-Earth Asteroids and Their Next Observing Opportunities

[Ron Baalke]

http://neo.jpl.nasa.gov/news/nhats.html
      
New Website Tool Now Available For Identifying Mission-Accessible
Near-Earth Asteroids and Their Next Observing Opportunities

NASA/JPL Near-Earth Object Program Office
March 20, 2012

Note: Website tool is available here: http://neo.jpl.nasa.gov/nhats/ 

Observers, mission planners, and other interested users are invited to
use a new website tool to view a list of near-Earth asteroids that are
among the most accessible for future robotic or human space flight
round-trip rendezvous missions. For each of up to several hundred
asteroids listed, the following information is available:

    * Absolute magnitude (H).
    * Estimated diameter (meters).
    * Minimum delta-V mission and the corresponding round trip flight
      time. Delta-V, in km/s, is defined here as the total velocity
      change required for the spacecraft to depart from a 400 km
      circular Earth orbit, rendezvous with the NEA and return to Earth
      with an entry velocity less than the specified threshold of 12 km/s.
    * Minimum mission duration time (round trip time in days) and the
      corresponding mission delta-V.
    * The number of viable trajectories found for that NEA, which is a
      proxy for its accessibility.
    * The next optical observing opportunity and the peak apparent
      visual magnitude.
    * The next Arecibo radar observing opportunity and the corresponding
      signal to noise ratio (SNR).
    * The next Goldstone radar observing opportunity along with the
      corresponding SNR.
    * Metric for orbit accuracy (Orbit Condition Code).
    * Orbit solution ID. 

Users can customize the table of accessible NEAs by specifying limits on
total delta-V, mission duration, stay time at the asteroid, launch date
interval, asteroid absolute magnitude, and orbit condition code. The
table can be sorted on almost all the bulleted items above.

Clicking on each object's designation takes the user to an
object-specific page, which provides additional details, including a
plot showing total mission delta-V for each combination of mission
duration and launch date (2015 - 2040). Another click on the object's
designation opens a new window that provides orbital and physical data
for the object.

The Near-Earth Object Human Space Flight Accessible Targets Study
(NHATS) began in September 2010 under the auspices of NASA Headquarters
Planetary Science Division of the Science Mission Directorate in
cooperation with the Advanced Exploration Systems Division of the Human
Exploration and Operations Mission Directorate. Its purpose was to
identify any known Near-Earth Objects, particularly Near-Earth Asteroids
(NEAs) that might be accessible by future human spaceflight missions.
The Goddard Space Flight Center (GSFC) and the Jet Propulsion Laboratory
(JPL) independently performed the first phase of the NHATS study in
parallel to validate the results.

NEAs are discovered almost daily, and often the time just after
discovery is also the optimal time to provide follow-up observations to
secure their orbits and characterize their physical nature. These
follow-up observations are particularly important for those NEAs that
could become potential future mission targets. The goal behind this
website is to monitor these NEA discoveries daily and determine if any
among them warrant additional study as they might become attractive
mission targets.

Brent Barbee (GSFC) developed the process that automatically downloads
orbital information on newly discovered NEAs from the JPL Small Bodies
Database (SBDB) on a daily basis. He then performs trajectory
calculations using the method of patched conics for the spacecraft and
with full precision ephemerides for the Earth and NEOs obtained from
JPL's Horizons system to determine which among them may meet the NHATS
accessibility constraints. The results of this daily analysis are then
immediately uploaded to the NHATS table. A process generated by Paul
Chodas (JPL) then provides, for each NHATS-compliant NEA, the details of
future observation opportunities that might allow the NEA orbit to be
improved with follow-up optical astrometric data. Some of these
observing opportunities would also allow the NEA's physical nature to be
characterized using photometric and spectroscopic observations. In cases
where there are future close Earth approaches, radar astrometric and
physical characterization observations may be possible; these
opportunities are listed as well.

Working closely with Brent Barbee and Paul Chodas, Alan Chamberlin (JPL)
was largely responsible for creating this Accessible NEAs website.

Website tool is available here: http://neo.jpl.nasa.gov/nhats/