**FROM PRESENT SURVEYING TO FUTURE PROSPECTING OF THE ASTEROID BELT.**
P.E. Clark^1^ S.A. Curtis^2^, M. Rilee^1^, and C. Cheung^2^,
^1^Affiliation: L3 Communications, Government Services, Inc., 3750
Centerview Drive, Chantilly, VA 20151, Correspondence: Code 695,
NASA/GSFC, Greenbelt, MD 20771, Email: Pamela.clark@ gsfc.nasa.gov,
^2^Affiliation: Code 695, NASA/GSFC, Greenbelt, MD 20771.

**Introduction:** We have applied a future mission architecture, the
Autonomous Nano-Technology Swarm (ANTS), to a proposed mission for in
situ survey, or prospecting, of the asteroid belt, the Prospecting
Asteroid Mission (PAM) as part of a NASA 2003 Revolutionary Aerospace
Concept (RASC) study.\[1\] ANTS architecture builds on and advances
recent trends in robotics, artificial intelligence, and materials
processing to minimize costs and maximize effectiveness of space
operations \[2,3,4,5,6,7,8\]. PAM and other applications
\[1,9,10,11,12\] have been proposed for the survey of inaccessible, high
surface area populations of great interest from the standpoint of
resources and/or solar system origin.

The ANTS architecture is inspired by the success of social insect
colonies, a success based on the division of labor within the colonies
in two key ways: 1) within their specialties, individual specialists
generally outperform generalists, and 2) with sufficiently efficient
social interaction and coordination, the group of specialists generally
outperforms the group of generalists. Thus systems designed as ANTS are
built from potentially very large numbers of highly autonomous, yet
socially interactive, elements. The architecture is self-similar in that
elements and sub-elements of the system may also be recursively
structured as ANTS on scales ranging from microscopic to interplanetary
distances.

Here, we analyze requirements for the mission application at the low
gravity target end of the spectrum, the Prospecting Asteroid Mission
(PAM), and for specialized autonomous operations which would support
this mission \[1,10,11,12\]. ANTS as applied to PAM involves the
activities of hundreds of individual specialist 'sciencecraft'. Most of
them, called Workers, carry and operate eight to nine different
scientific instruments, as listed in the table, including spectrometers,
ranging and radio science devices, and imagers. The remaining
specialists, Messenger/Rulers, provide communication and coordination
functions among specialists operating autonomously as individuals, team
members, and subswarms. Individual nanocraft are on the order of a
kilogram in mass, translating into gossamer structures. Onboard power
requirements, met by small nuclear batteries, must be on the order of
milliwatts. The non-expendable propulsion system is based on
autonomously deployable and configurable solar sails, a system suitable
to low gravity well targets.

**Methodology:** The first step in this process was the development of a
patented conceptual model, called a neural basis function, which
combines the capability of autonomous and collective interaction, or
bi-level intelligence, for each component, subsystem, or agent \[1\].
Individual operational components connect to other operational
components and to heuristic level decision making components through a
specially designed interface. This structure is redundant at each level.
We have also generated scaled physical models of spacecraft both
packaged and fully deployed, as well as of onboard structures such as
solar sail and instrument platform. to illustrate the modularity,
configurability, and orders of magnitude scalability. Formulation of
requirements and operational scenarios for PAM \[1\], including
propulsion, navigation, and data taking operational interactive
requirements and scenarios, are driven by the variable size and
irregular mass distribution and meteoritic composition of asteroid
targets in the surrounding low gravity environment.

**Discussion:** The Figure illustrates the application of the neural
basis function in the context of a survey mission. Potential science
goals for PAM provide this context (Table). Mainbelt asteroids highly
variable in composition and/or dynamic properties. Potential targets are
separated by distances of hundreds of thousands of kilometers making
detection and location a problem. The numbers and distances require
large numbers of multi-specialist teams.

What would the structure and size of a swarm of specialists need to be?
If a minimum of four specialists are needed for collective decision
making, as required in the neural basis function (Figure), and we allow
for ten instrument specialist teams (Table), that means a minimum size
of 40 in a subswarm. Allowing for five to ten percent attrition over the
few years required for a survey, numbers of specialists should be a
minimum of 50 in a subswarm. The use of ten to twenty of such subswarms
should allow for the in situ characterization of hundreds of asteroids
over the course of the traverse of the belt. The difficulty in observing
irregular, rapidly moving, and often poorly illuminated objects is
largely overcome by the ANT sciencecraft capability to optimize of
viewing conditions for each instrument, a capability which drives the
need for revolutionary ANTS architecture. Each specialty would have
different viewing requirements and thus operational scenarios.
Increasing the numbers in each specialty team could speed up the process
of data collection for spectrometers, which have the most stringent
requirements, and potentially allow for higher resolution mapping. For
this reason, we prefer to double subswarm size to approximately 100.

Our concept includes autonomous assembly and packaging of components
prior to deployment. Configurable, addressable modular components form
smart, self-deploying systems for assembly operations driven by the need
for minimize bandwidth (resources) and human involvement (labor).
Components would be composed of carbon nanotubule strands (tethers) or
fibers (surfaces) reversibly spooled and deployable from NEMS nodes,
allowing for orders of magnitude decrease in packaging volume. 1000
smart 10 centimeter, 1 kg cubic boxes would create a 1000 kg 1 meter
cube. Distributed networks of messengers, with enhanced communication
systems, would store, transmit, and carry data over interplanetary
distances.

**Conclusions**: The ANTS approach would allow simultaneous survey of
many interesting asteroids by teams of flexible instrument specialists
configured for optimal operation. Redundancy allows for planned high
attrition of individual workers, including the return of communication
specialists, or messengers, without compromising ongoing prospecting.
Use of scalable, reversibly deployable gossamer structures would
minimize the weight and power requirements, allowing maximum change in
configuration during operation as well as minimum packaging size prior
to deployment. These studies imply that ANTS architecture is an
efficient approach for studying the asteroid belt, depending only on
already anticipated incremental advances in technology.

**References:** \[1\] Curtis et al (2004) The Autonomous NanoTechnology
Swarm, NASA RASC Final Report (in preparation); \[2\]Curtis et al (2000)
Abstracts of IAF, 51st Congress; \[3\] Clark et al (2001) AAS/DPS, BAAS,
vol. 33, no. 3; \[4\] Clark et al (2001) EOS Trans. AGU, 82 (47), 2001;
\[5\] Clark et al (2002) LPSC XXXIII, 1394; \[6\] Clark et al (2002) EOS
Trans AGU, P521-01, \[7\] Curtis et al (2003)Abstracts, 3^rd^ Intl
Workshop on Satellite Constellations and Formation Flying, Pisa, Italy;
\[8\] Clark et al (2003) 34^th^ LPSC; \[9\] Curtis et al (2003) Saturn
Autonomous Ring Array, NASA RASC Proposal; \[10\] Rilee et al \[2002\]
IEEE Aerospace Conf, Big Sky, MT, 209; \[11\] Curtis et al (2003) IEEE
Aerospace Conference, Big Sky, MT; \[12\] Curtis et al (2003), Large
Autonomously Reconfigurable Antennas for Space-based Radio Astronomy,
NASA MSMT Proposal.

**Acknowledgment**: Support for this work has been provided through NASA
contract NAS5-99189, subcontract 0299189EER, with ITMI.

Return to or visit ANTS home or SARA web page:

<http://ants.gsfc.nasa.gov/pamtest/website.html>

<http://ants.gsfc.nasa.gov/pamtest/pam.html>

<table style="width:100%;">
<colgroup>
<col style="width: 9%" />
<col style="width: 9%" />
<col style="width: 9%" />
<col style="width: 9%" />
<col style="width: 10%" />
<col style="width: 10%" />
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<col style="width: 10%" />
<col style="width: 10%" />
<col style="width: 10%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="10"><strong>Science Context Table for PAM</strong></td>
</tr>
<tr class="even">
<td><blockquote>
<p><strong>Modes of Study</strong></p>
</blockquote></td>
<td colspan="3"><blockquote>
<p>Interior structure and origin</p>
</blockquote></td>
<td colspan="4"><blockquote>
<p>Surface characterization with spectrometers</p>
</blockquote></td>
<td><blockquote>
<p>physical/Dynamic</p>
</blockquote></td>
<td><blockquote>
<p>Detection/Location</p>
</blockquote></td>
</tr>
<tr class="odd">
<td><blockquote>
<p><strong>Measurements</strong></p>
</blockquote></td>
<td><blockquote>
<p>magnetic field</p>
</blockquote></td>
<td><blockquote>
<p>compositional variations</p>
</blockquote></td>
<td><blockquote>
<p>photogeology,stratigraphy</p>
</blockquote></td>
<td><blockquote>
<p>regolith particle properties</p>
</blockquote></td>
<td><blockquote>
<p>mineral assemblages</p>
</blockquote></td>
<td><blockquote>
<p>volatiles, organics</p>
</blockquote></td>
<td><blockquote>
<p>major, refractory elements</p>
</blockquote></td>
<td><blockquote>
<p>morphology,gravity,spin</p>
</blockquote></td>
<td><blockquote>
<p>imaging triangulation</p>
</blockquote></td>
</tr>
<tr class="even">
<td><blockquote>
<p><strong>Specialists</strong></p>
</blockquote></td>
<td><blockquote>
<p>Magnetometer</p>
</blockquote></td>
<td><blockquote>
<p>All spectrometers</p>
</blockquote></td>
<td><blockquote>
<p>Visible Imager</p>
</blockquote></td>
<td><blockquote>
<p>Thermal/Radio Sounder</p>
</blockquote></td>
<td><blockquote>
<p>UV/Vis/IR</p>
</blockquote></td>
<td><blockquote>
<p>Neutron/Gamma-ray</p>
</blockquote></td>
<td><blockquote>
<p>X-ray/Gamma-ray</p>
</blockquote></td>
<td><blockquote>
<p>Imagers/Rangers/Radio Science</p>
</blockquote></td>
<td><blockquote>
<p>Visible Imagers</p>
</blockquote></td>
</tr>
</tbody>
</table>