**AN Approach to Minimum Cost NEO Characterization**. R. Reinert^1^ , R.
Dissly^2^, and Scott Mitchell^3\ 1^Ball Aerospace & Technologies Corp.
(1600 Commerce St., Boulder, CO 80301, 303-939-5953, rreinert@ball.com),
^2^Ball Aerospace & Technologies Corp. (1600 Commerce St., Boulder, CO
80301, 303-939-5763, rdissly@ball.com), ^3^Ball Aerospace & Technologies
Corp. (1600 Commerce St., Boulder, CO 80301, 303-939-4386,
smitchel@ball.com)

**Introduction**. The close proximity of Near Earth Objects (NEOs) make
them attractive targets for detailed characterization via rendezvous
spacecraft missions, for purposes of basic scientific inquiry, or to
provide improved understanding for potential planetary defense or
resource exploitation. This poster describes three prospective NEO
characterization mission concepts that use well-characterized chemical
and electric propulsion approaches and a new generation of launch
systems to provide three unique approaches to minimizing the cost of NEO
characterization missions. Representative spacecraft designs are
summarized for each mission concept, as are example low-thrust
trajectories for the electric propulsion option. We present cost trades
that summarize the total mission cost for all three approaches, and
recommend a minimum cost approach to NEO Characterization.

**NEO Scout Low-Cost Spacecraft Concept.** The NEO Scout mission concept
is designed to minimize mission cost by using a very low-cost
spacecraft. The NEO Scout approach uses a basic single-string
architecture and a simple hydrazine monopropellant propulsion approach
to rendezvous with a single NEO after a launch to a C3 of 5-10 by a
Taurus, Falcon-5, or Minotaur-V medium-cost LV.

**NEO Sentry Minimum Launch Cost Mission Concept.** The NEO Sentry
mission is aimed at minimizing mission cost by using the lowest cost
launch vehicle. It uses a high performance dual-mode bipropellant
propulsion approach and ultra-low mass to rendezvous with a single NEO
after launch to a 185-km LEO by a bargain-basement Falcon-1LV.

**NEO Explorer (NEOX) Solar Electric Propelled Spacecraft Concept.** The
NEOX mission concept minimizes mission cost by enabling a single
spacecraft to rendezvous with multiple NEO's and by allowing multiple
S/C to be launched by a single LV. The NEOX mission profile takes
advantage of the low-thrust mission designs described below to
rendezvous with up to three separate NEO\'s, or to perform a single
rendezvous with a NEO inaccessible to chemically propelled vehicles. SEP
efficiency lowers the NEOX S/C mass sufficiently to allow 2 such S/C to
be launched on a single Delta-II, or four to be launched on the smallest
Delta-IV, in principal allowing a single launch to support rendezvous
with up to 12 separate NEO's.

**Low Thrust Trajectory Mission Design.** A key approach to mission cost
minimization is the ability to manifest multiple S/C on a single LV. Our
analyses show that Libration point trajectories and the high performance
of SEP propulsion can be used to enable multiple low-thrust spacecraft
launched together to reach different NEO's. Such a mission would
manifest two to four spacecraft on a single launch vehicle, which would
launch all of them together on the same trajectory to one of the
earth-moon libration points (L1 or L2, C3 = -0.69). Once near the
libration point, small impulses would take advantage of the instability
of libration point orbits to send the different spacecraft on
trajectories to separate NEO's.

**Cost Trades**. To compare the cost-effectiveness of the 3 different
mission approaches described above, we use the metric of "Cost per
Rendezvous", as some of the LV options allow the prospect of launching
multiple spacecraft, and the SEP spacecraft have enough Delta-V to
permit multiple rendezvous. We will present representative total mission
cost ranges for the spacecraft classes described, including payload and
operations costs, as well as estimated cost ranges for the suggested
launch vehicles. Of note, use of a bipropellant approach can
significantly reduce launch cost by allowing use of a smaller, less
costly LV such as the Falcon-1. A primary conclusion is that SEP enables
a single launch to support multiple rendezvous, reducing cost per
rendezvous by up to a factor of two across a wide range of mission
profiles.