SMART Power Systems for ANTS Missions

P.E. Clark^1^, S.R. Floyd^2^, S.A. Curtis^3^, M.L. Rilee^1^

^1^L3 Communications GSI, 3750 Centerview Drive, Chantilly, VA 20151\
located at Code 695, NASA/GSFC, Greenbelt, MD 20771\
^2^Code 691, NASA/GSFC, Greenbelt, MD 20771\
^3^Code 695, NASA/GSFC, Greenbelt, MD 20771\
301-286-7457 pamela.clark@gsfc.nasa.gov

**Abstract.** ANTS Architecture is based on Addressable Reconfigurable
Technology (ART) adaptable for the full spectrum of activities in space.
ART systems based on currently available electromechanical (EMS)
technology could support human crews on the lunar surface within the
next 10 to 15 years. Two or more decades from now, NEMS (Super
Miniaturized ART or SMART) technology could perform fully autonomous
surveys and operations beyond the reach of human crews. Power system
requirements would range from 1 kg to generate tens of Watts for near
term ART applications, such as a lunar or Mars Lander Amorphous Rover
Antenna (LARA), to \<0.1 kg to generate hundreds of mWatts for more
advanced SMART applications.

# Power systems for future missions

Availability of small radioisotope power system (RPS) technology will
enable opportunities for scientifically valuable missions which were
previously unachievable (Mondt, 2000; Johnson, 2002). Batteries based on
this technology will allow modest vehicles to operate in areas of
minimal to non-existent insolation over long periods of time, in
unilluminated hemispheres of terrestrial planets, or in or on targets
beyond the asteroid belt. Such vehicles would include subsatellites and
small rovers with reasonable payloads with power requirements in the
tens of watts to tens of milliwatts range, equipped with supplemental
systems for peak load operations. This power generation technology is
particularly applicable to ANTS architecture applications, which are
extremely efficient in operation, and thus have modest power and minimal
weight requirements (Curtis et al, 2000; Clark et al, 2004a, 2004b,
2004c).

# The ANTS Concept

The Autonomous NanoTechnology Swarm (ANTS) Architecture is based on
Addressable Reconfigurable Technology (ART) adaptable for the full
spectrum of activities in remote/hazardous environments such as space.
The architecture is based on the tetrahedron as a building block, with
edges consisting of struts deployed from nodes at apices. Tetrahedra are
combined to form space-filling networks of nodes and struts. ANTS
systems based on available electromechanical technology (@ 1kg/m2) could
support human crews on the lunar surface within the next 10 to 15 years.
A prototype of such a system is currently under construction. ANTS
systems based on NEMs (Super Miniaturized ART or SMART) technology (@
\>5g/m2) could perform fully autonomous surveys and operations beyond
the reach of human crews two or more decades from now. Basic structural
components are highly modular, addressable arrays of robust nodes, from
which highly reconfigurable struts, acting as supports or tethers, or
surfaces, are efficiently reversibly deployed/stowed, transforming the
structures as required for all functions in space and on the ground.
Reusability of ANTS components thus limits the need for resources, along
with cost, mass, size, bandwidth, power, and, of course, expendables.
ANTS systems have already been conceptualized for three applications
spanning three decades (LARA: Lander Amorphous Rover Antenna; PAM:
Prospecting Asteroid Mission; SARA: Saturn Autonomous Ring Array) (Clark
et al, 2004b, 2004c, 2004d) where solar illumination could be minimal,
including high latitude or polar regions, below ground, or beyond 3 AU.
Thus, the use of small radioisotope power systems is particularly
appealing.

# ANTS Applications

## Near Term: The LARA Applications

![](media/image1.jpeg){width="3.5062992125984254in"
height="3.1251968503937007in"}Lander Amorphous Rover Antenna (LARA)
(Figure 1, Table 1) is a near term EMS level mission concept applicable
to autonomous or human/robotic exploration of planetary surfaces. (Clark
et al, 2004b) (See LARA: The Movie at the official ANTS website). The
LARA vehicle transforms itself to follow the required function (Table
2). These functions could include transmitting or receiving information,
carrying a payload such as a sample collector/analyzer, or providing of
a shelter or storage facility. These functions could be performed
autonomously, or through interface with crew either in situ or remote.

**Figure 1**. LARA Mission Components, including landers on top,
antennae in crater and astronaut shelter in foreground. Amorphous rover
in various contortions stretching from back to front of scene

**Table 1.** LARA Characteristics and Requirements

Characteristic Requirement

Launch Date: 2010-1015\
Duration and Location: Months or even years, 1.0 -- 2.0 AU\
Environment: low G, adequate illumination, planetary surface\
Spacecraft Mass, Materials: 10-50 kg, 10-100 g/cm^2^\
Engineering: 3 axis stabilized spacecraft, Tet walker surface, EMS
components\
Power system: Solar Cells or Nuclear Batteries\
Power system mass: 5 kg\
Power requirement: 100 Watts\
Torque at node: 50 kg\
Propulsion system: Space Chemical Mini-thruster/Ground Node and Strut\
Operation Notes:\
Autonomous or through link with crew, Individual or collective
operation, Cover tens of kilometers per day\
No single point failure, Robust to minor faults and major failure

LARA tetrahedral frame components are electromechanical structures
forming a network of struts which are reversibly deployable/stowable
from EMS or MEMS nodes equipped for wireless operation. Payload and
subsystem components are attached 'inside' the tetrahedral network,
between layers of nodes, and thus protected. After manufacture, the
frame could be reduced to a minimum strut extension size for shipping to
a launch or deployment size. Nodes and Struts make up the frame and
would be used for all functions The greatest number would be

structural nodes which deploy/stow flexible struts based on one of
several design schemes, ranging from a) telescoping struts extended or
contracted by various mechanisms, including cables or springs, and b)
double 'tape measure' device which links or unlinks the oppositely wound
flexible rolled sheets. Rolls with opposite orientations develop great
tensile strength when combined. Similar nodes could be used as
attachment points for payloads, such as instruments (Clark et al, 2004a,
2004c; Curtis et al, 2004). An outer covering for the LARA craft (Clark
et al, 2004a, 2004c) could be provided by specially designed nodes which
would deploy carbon fiber composite 'memory' sheets with relatively low
aerial density using Polymer/Carbon Nanotube Composite (PNC) springs and
structural elements (ESLI website, PF 2004 website).

**Table 2.** LARA Forms Follow Function

Function Form

Lander/Space Mobility: Flattened with mini-thruster nodes\
Amorphous Rover/Surface Mobility Size for terrain scale, Gait for
roughness, Shape for required movement:\
amoeboid for very rough, slither for steep traction, spheroid for
smooth\
Payload Carrier/Transportation Same as rover\
Antenna/Communication Beacon/Bowl shape, single or arrayed\
Shelter Provider Extended cover over natural enclosures or hut-like in
open\
Specialized Task/Reconnaissance Form stable platform for measuring or
collecting operation

The LARA vehicle transforms itself as necessary to perform required
functions (Figure 1, Table 2). The LARA Lander is formed by flattening
the tetrahedral network so that mini chemical propulsion thrusters are
effectively attached around the periphery. The LARA Amorphous Rover is
created by continuous contraction and extension of struts in a way that
optimizes the efficiency of movement across a terrain, and thus depends
on the variability and scale of the relief and roughness in a given
terrain. A payload could be placed within active or passive nodes on the
'inside' of the continuous tetrahedral structure. LARA vehicle is
transformed into an Antenna whenever significant bandwidth communication
is required. The tetrahedral network itself, bowl-shaped above with a
broader base below, would be equipped to receive and transmit data. The
same vehicle could be transformed into a shelter for crew or equipment
by creating a tent-like structure. A key to performance of such a system
is efficiently designed mechanisms based on opposing force principles, a
crucial design feature in biological locomotion (Clark et al, 2004a).

Ultimately, with interconnecting, space filling tetrahedral material,
very high degree of freedom movement emerges, more 'natural' than
wheels, effectively allowing 'flow' across a surface and into a
particular morphological form (Figure 2). The ability to control the
timing and extent of strut deployment allows control of the scale and
gait of the rover. A single tetrahedron, like the prototype we are
currently building, rocks from side to side as it moves forward. Put an
additional strut at each node and divide that tetrahedron into 4
tetrahedron (like the 4Tet we are proposing to field test), and an inner
space is created for attachment of a payload. In a 12Tet model, motion
is far more continuous. Clear amoeboid-like movement can be observed for
very rough surface, more 'natural' than wheels, effectively allowing
'flow' across a surface or into a particular morphological form. For a
very smooth surface, or for 'storage' the minimum surface area spheroid,
rolling across the ground, could be effective. Uphill climb or slipping
through narrow openings could require a slithering snakelike morphology.
When surmounting obstacles, the rover could either change its scale,
growing in size, or use a climbing motion, pulling itself over using
facets on the obstacle itself as 'toe holds'.

A wide variety of mission scenarios could be employed in using LARA
systems. Deployment and use could be either entirely robotic and
autonomous, or through a human interface. The human interface could be
remote in near real time, through telepresence, or in situ, acting as
extensions for a human crew active on the surface. LARA craft could
first land payloads autonomously, then form roving 'advance
reconnaissance teams', mapping, gathering and analyzing samples and
images of the terrain for use in site selection. Such analysis of
samples, to determine elemental, mineral, water, biogenic material, or
rock abundances, or terrains, to determine stratigraphy, morphology,
age, would inevitable lead to the identification of sites with important
clues on the origin of planets, the solar system, or life itself.
Whenever necessary, rovers could form antenna to transmit findings and
receive instructions. Such systems could also be used to provide
shelter, by creating, seeking, and enclosing natural semi-enclosed
formations. LARA craft could also find, collect, or mine materials of
use in exploration or construction. A network of LARA craft could be
used to form a temporary or permanent communication, navigation, or
observatory facilities.

![](media/image2.jpeg){width="4.804724409448819in"
height="4.717322834645669in"}**Figure 2**. Tetrahedral Walker movement
by continuous strut extension and contraction, evolving from simple,
punctuated movement of single tetrahedron on left, to more complex,
smoother climbing of 12Tetrahedron in middle, to high degree of freedom
'flow' of a continuous tetrahedral network on right. 12Tet W alker or
above is proposed for LARA.

## Near Future: The PAM Application

The Prospecting Asteroid Mission (PAM) application, the first
application considered for ANTS architecture (Figure 3, Table 3)
requires MEMS (Miniaturized ART or MART) to NEMS (SMART) level
application of the ANTS architecture. This technology should be
available in about two decades, in keeping with long-term Exploration
Initiative plan for robotic exploration of the next target, mainbelt
asteroids, beyond Mars.

Whereas the traditional missions excel at exploring larger asteroids
sequentially, the PAM concept is designed for the systematic studying of
an entire population of objects (Curtis et al, 2000, 2004; Clark et al,
2004c). The ANTS approach involves the use not of a smart spacecraft
with 'drones' but of a totally autonomous truly distributed intelligent
network of sensors, or sciencecraft, with solar sails for propulsion,
and thus minimal requirement for expendables (See also ANTS: The Movie
at the official ANTS website). Sciencecraft each have specialized
instrument capability (e.g., advanced computing, imaging, spectrometry,
etc.) and heuristic systems that are both adaptable and evolvable.
Subswarms of sciencecraft can operate autonomously, allowing the optimal
gathering of complimentary measurements for selected targets. Many
subswarms would operate simultaneously within a broadly defined
framework of goals to select targets from among available candidate
asteroids.

PAM is a 1000-member swarm of picoclass (1 kg) autonomous sciencecraft
based on carbon-based NEMS technology and utilizing Super Miniaturized
Addressable Reconfigurable Technology (SMART) (Rilee et al, 2004a,
2004b). The basic design elements are self-similar low-power,
low-weight, addressable, reconfigurable components and systems capable
of operating as fully autonomous, yet adaptable units as called for by
swarm demands and environmental needs. Craft use highly configurable
solar sails capable of autonomous attitude control, a highly
maneuverable, no expendables propulsion system well suited to this
application. The swarm would be composed of 10 science specialist
classes (approximately 100 members of each class), identical except for
one specialty 'instrument'. Classes include Leader/Messengers
(CPU/Communication enhanced), and sciencecraft including imagers,
various spectrometers, altimeters, radio science, and magnetometers. The
swarm would be divided into 10 to 20 subswarms with approximately equal
numbers of each class in each subswarm. Within each subswarm, each class
would operate autonomously at an asteroid target, because orbital
configuration and viewing strategy for the classes are highly variable
and depend on the requirements of the class 'instrument'. 10 to 20
subswarms would operate concurrently. Target observation times would be
on the order of one month. Typical distances of hundreds of thousands of
kilometers between kilometer-size asteroids would allow detection (by
imagers) and selection of the next target even before departure from a
given target, and travel to that target on the order of weeks. Thus,
tens or even hundreds of asteroids could be explored during a the
anticipated 5 year traverse of the asteroid belt.

![](media/image3.jpeg){width="5.064566929133858in"
height="2.3751968503937007in"}**Figure 3**. PAM Mission Scenario,
including from left to right across, Solar Sail trip to asteroid belt,
target of opportunity selection with imagers, separation of subswarms,
virtual team operation of subswarm at target, target characterization,
return of Messenger with data from multiple target encounter.

**Table 3.** PAM Requirements

Characteristic Requirement

Launch Date 2025\
Duration and Location 10 years from 1.0 to 3.5 AU\
Environment low G, high target density, solar illumination\
Vehicle Mass and Aerial Density 1 kg, 1 to 5 g/cm^2^\
Power system, mass requirement Nuclear batteries, 0.25 kg, 100-300
mWatts\
Propulsion system and mass Solar Sails, 0.5 kg, 10^3^ change in
effective sail area\
Engineering 3-axis stable spacecraft, MEMS components\
Organization 1000 spacecraft, 10 specialist classes, 10-20 subswarms,
simultaneous operation\
Operational notes Deep space with no direct link to Earth, individual
Messengers return data\
Full instrument suite deployed 1 month/asteroid optimal science\
Concurrent operations \~10 asteroids, \>50 targets per year\
No single point failure, robust to failure, Optimized in spite of 10%
attrition/year

Each class (Table 4) would employ different strategies in the use of
components and subsystems during the active part of PAM (Curtis et al,
2000, 2004). Leader/Communicators would be enhanced for high level
communication and processing functions which would occur at some
distance from a target to keep the subswarm in view, and wouldn't
require the fine adjustment in attitude control needed by sciencecraft
requiring measurements closer to the target. Science operations could
vary substantially from instrument to instrument. Visible imaging
spectrometers would be used extensively during cruise to detect
potential targets, and then refine knowledge of the location and nature
of the target on the way to the selected target. Spectrometers (X-ray,
Near IR, Gamma-ray, Neutron) would acquire compositional data.
Altimeters and radio science packages would provide dynamic models. The
required viewing conditions for each instrument vary considerably, and
might well affect the choice of targets. Optimal operation is easily
accommodated in either near terminator orbits or darkside stationkeeping
for the majority of instruments. However, the Near Infrared and X-ray
spectrometers, crucial for determining composition, are the most
difficult instruments to accommodate, requiring as much close proximity,
illumination and direct (subsolar point, nadir pointing) geometry as
possible. Real 'stationkeeping' would be virtually impossible to achieve
on the sunlit side of an asteroid due to combined photonic and
gravitational forces. On the other hand, an equatorial orbit of a string
of instruments in a given spectrometer class would be possible, provided
the effective sail area can be decreased by a factor of a thousand,
something which should be very achievable to a 10,000 partially
deployable facets. PAM spacecraft would study a selected target by
forming 'Virtual Teams' (Clark and Iyengar, 2002; Clark et al, 2004c).
'Virtual Instrument Teams' would be formed from those within each class,
to optimize data acquisition. Another strategy would involve providing a
comprehensive set of measurements to solve a particular scientific
problem, by forming 'Virtual Experiment Teams' of multiple sensors
(Table 4).

![](media/image4.jpeg){width="5.584645669291339in"
height="2.6251968503937007in"}**Figure 4**. PAM Components and
Behaviors. Left top, model Pam Spacecraft showing sail on sail frame in
background with instrument bearing space platform in foreground. Left
bottom, model node releasing/spooling mechanism for struts and relative
size of nodes on 2000 penny. On right, Sail configuration, from top to
bottom, for self repairing by regrowing struts, changing shape, and
changing sail deployment patterns for attitude control.

**Table 4.** PAM Virtual Teams within Subswarm

Class/Instrument Role/Requirement

Leader/Messenger Processing, Strategy, Communication/Out of way yet
within range\
Workers Data Gathering\
Imager Target Detection, 3D Model, Photogeology/Some illumination\
Visible/IR Spectrometer Mineral Abundances/Close, Nadir, Full sun\
X-ray Spectrometer Major Elements/Close, Nadir, Full sun\
Gamma-ray/Neutron Spectrometer Heavy Element, Volatiles/Close, Nadir,
Fill FOV\
Altimeter (Ranging) Shape, 3D Model,Topography, Morphology/Nadir
Pointing\
Radio Science/Magnetometer Gravity and Magnetic Fields, Interior, 3D
Model/Over poles\
Radio Sounder/IR Radiometer Regolith Characteristics/Close, Nadir\
Neutral Mass Spectrometer Volatile characterization/Close, Full sun

Using this approach to survey the main asteroid belt, a population
consisting of millions of small, remote bodies, is most cost/effective
in terms of science and resource exploration. Although a large fraction
of solar system objects are asteroids, relatively little data is
available for them because the vast majority of them are too small to be
observed except as single point measurements except in close proximity
(Clark et al, 2004c). Within the asteroid population are remnant
planetesimals dating back to formation of solar system, the most
primitive, unmodified material known. These small bodies originated in
the transitional region between inner (rocky) and outer (solidified
gases) solar system, the asteroid belt. Determination of the systematic
distribution of physical, compositional, and dynamic properties within
the asteroid population is crucial in the understanding of the solar
system formation. In addition, there has been interest in asteroids as
sources of exploitable resources. Far more reconnaissance is required
before a true assessment is achieved. Such an assessment could focus on
a systematic survey.

PAM spacecraft (Figure 4) components are nanotechnology-based SMART
structures forming tetrahedral networks of nano-struts, tethers, or
sheets which are reversibly deployable/stowable from MEMS or NEMS nodes
equipped for wireless operation (Curtis et al, 2004; Clark et al,
2004c). Such mechanisms require low mass, low wattage power systems.
Most nodes are used to deploy/stow struts using a mechanism which links
or unlinks oppositely wound tubules (Figure 4). Tubules with opposite
orientations develop great tensile strength when combined, or vice
versa, as in fact, to a somewhat lesser extent, two such EMS tape
measures would. Similar nodes are also used to deploy/stow tethers or as
attachment points for nanocomponent subsystems, such as instruments.
Nodes could also be used to deploy sheets consisting of carbon-based
materials, including nanotubules, or even highly compressible carbon
fiber composite sheets with 'memory' and relatively low aerial density
(5 g/cm^2^) (ESLI website). Such nodes would be used in the 100 square
meter solar sail which would consist of 10,000 100 sq cm triangular
facets supported by a space frame consisting of two layers of
interconnected nodes, forming a lightweight 3D truss structure. Very
effective solar sail navigation and attitude control could potentially
be achieved by a 10,000 reversibly deployable component sail on a highly
reshapable frame seen in Figure 4 (See Sail Animations at official ANTS
website). Attached to the space frame by a network of long tethers would
be a small space platform consisting of three layers of interconnected
nodes, making a more robust framework to which all subsystems are
tethered. The extent and direction of all tether deployment can be
controlled. This design allows the propulsion system to operate
completely independently of all other subsystems.

![](media/image5.jpeg){width="5.322834645669292in"
height="2.1255905511811024in"}**Figure 5**. ANTS architecture for Pam
Manufacturing (top) and deployment (bottom) sequences.

In fact, the spacecraft assembly process employs ANTS architecture and
is part of the PAM mission concept. at the MEMS level or higher (Curtis
et al, 2004; Clark et al, 2004c) (Figure 5) (See also Manufacturing
Movie at the official ANTS website). The assembly facility would
probably take advantage of readily available solar power near the Earth
rather than nuclear power. The entire spacecraft is initially assembled
elsewhere and stowed (predeployment) in a 100 cm^3^ SMART box, allowing
for a much smaller pre-deployment size and minimizing 'cargo'
requirements during travel from the assembly to deployment sites. The
box is equipped with nano communication and propulsion devices, so it
can travel and communicate with the swarm for short distances in space.
Once the box delivers and releases the spacecraft, it can form a flat
sheet and return itself for reuse. 1000 such boxed craft are initially
packaged in a 1 cubic meter SMART cube at the assembly site, for
delivery to the deployment site in deep space. The facility, which could
be located on the Earth or in a low G environment, is equipped to
generate tetrahedral networks of any size or shape, using ANTS
strut-deploying, layer-deploying, and instrument subsystem deploying
nodes.

## Future: The SARA Application

The Saturn Autonomous Ring Array (SARA) mission concept (Curtis et al,
2003; Clark et al, 2004d) is a suggested application for the Autonomous
Nano-Technology Swarm (ANTS) architecture (Figure 6, Table 5). The SARA
concept includes assembly of self-packaging, self-deploying,
self-similar components at facilities built on ANTS architecture as
described for the ANTS Prospecting Asteroid Mission (PAM).
Transportation requirements and capabilities are being considered as
part of a propulsion system trade-off study for SARA, which combines
navigating in low gravity with maneuvering in the high gravity regime of
Saturn's rings, demanding hybrid propulsion. The ANTS paradigm applies
well to exploration of high surface area and/or multi-body targets by
minimizing costs and maximizing effectiveness of survey operations.
Systems designed with ANTS architecture are built from potentially very
large numbers of highly autonomous, yet socially interactive,
specialists, in approximately ten specialist classes. The current
mission plans calls for a SMART solar sail 'hive' to ferry tethered
individual nanocraft out to the far edge of the asteroid belt. At that
distance, maneuvering individual craft with solar sails is not feasible.
A SMART propulsion system considered has been mini-thermal nuclear,
capable of self-configuring for control of thrust by varying the
temperature and criticality of the fuel element through changing shape
(Figure 6). Such a system should also be capable of providing adequate
power for other operations.

![](media/image6.jpeg){width="5.194488188976378in"
height="3.25in"}**Figure 6**: SARA Mission Scenario: On left, Mission
concept of individual craft deploying from Hive ship. On right, concept
of configurable nuclear propulsion system, with thrust directly related
to criticality and inversely related to propulsion system volume.

**Table 5.** SARA Requirements

Characteristic Requirement

Launch Date 2035\
Duration and Location 15 years from 1.0 to 5 AU\
Environment High G, high target density, adequate to minimal solar
illumination\
Vehicle Mass and Aerial Density Carrier 2000 kg, Individuals 1kg, 1
g/cm^2^\
Power system, mass requirement Nuclear batteries, Individuals 0.25 kg,
100-300 mWatts\
Propulsion system and mass Carrier: Solar Sails, 500 kg, Individuals:
Nuclear propulsion, 0.5 kg\
Engineering 3-axis stable spacecraft, NEMS components\
Attitude control Carrier change in effective sail area, Individual
change nuclear source criticality\
Organization 1000 spacecraft, 10 specialist classes, 10-20 subswarms,
simultaneous operation\
Operational notes Deep space with no direct link to Earth, individual
Messengers return data\
100's in situ observations ring particles, 1000's ring measurements per
day\
No single point failure, robust to failure, Optimized in spite of 10%
attrition/year\
Special challenge: rapid reconfiguration of nuclear propulsion system

SARA would perform in situ observations of Saturn's rings, both from the
individual particle and collective plasma standpoints. This population
is of great interest from the standpoint of solar system origin However,
such in situ observations of spacecraft-scale targets with high density
distribution in a large gravity well represents a challenge unachievable
by conventional (direct control of single spacecraft from Earth) or even
evolutionary (direct control of multiple spacecraft from Earth
surrogate) mission designs. Each nanocraft would be on the order of
kilograms in mass, and thus require gossamer structures for all
subsystems. Onboard power requirements, met by small nuclear batteries,
would be constrained to milliwatts. The hundreds or even thousands of
individual specialists include Workers, the vast majority, that acquire
scientific measurements, as well as Messenger/Rulers that provide
communication and coordination.

**Table 6**. SARA Science Activities

Specialist Measurement Mode of Study

Particle/Plasma Electrodynamics: Plasma, particles Particle populations\
Search Coil Electrodynamics: Waves View from outside of ring plane\
Magnetometer/E-Field Electrodynamics: Fields\
UV/Visible Imaging Ring thickness, density\
Mid to Thermal IR Reflectivity, size, volatility distribution\
Radio Sounder Reflectivity and Emissivity distribution\
\
APX, Laser ablation MS Refractory element abundances Individual
particles\
UV/Visible/IR Spectrometer Mineral Assemblages Collect thru ring\
Mass Spectrometer Volatiles, organics

Potential science goals for SARA (Table 6).provide the context for this
discussion. The high density distribution of particles on the scale of
particles size, combines with the high intensity gravity and magnetic
field environment to produce dynamic plasmas. Although composition is
essentially cometary with high volatile abundances, great variations
remain in the dust/gas ratio and the composition of dust component for
individual particles. Thus, a broad spectrum of in situ instruments,
with very different requirements, are required, with specialists
developing strategies to obtain in situ measurements as individuals,
teams, in a highly dynamic environment, as appropriate. Plasma,
particle, wave, and field detectors will probably fly just above or
below the ring plane to observe the result of particle interactions.
Imagers and spectrometers will need to develop a strategy for serial
rendezvous with individual particles through the ring. The high density
of particles, some nanocraft-scale, makes collision avoidance a problem
that must also be solved autonomously in situ. The numbers and distances
of these particles, as well as anticipated high attrition rate, require
large numbers of each specialist class. Allowing for a high attrition
over the couple of years required for a survey and initial size of
100/subswarm, ten to twenty of such subswarms should be able to
characterization of thousands of particles and ring features over the
course of the traverse of the rings.

# Power requirements for ants applications

Power system requirements (Table 7) would range from tens of Watts for
near term ART applications, such as a lunar or Mars Lander Amorphous
Rover Antenna (LARA), to hundreds of mWatts for more advanced SMART
applications. Are estimates are in line with Moore's Law: anticipated
power requirement should decrease by up to two orders of magnitude for
increments of EMS to MEMS and then from MEMS to NEMS technology. Several
kilograms are budgeted for the power subsystem for near term
applications, making the multiple RHU version of RPS technology usable,
with capabilities of tens of watts per kilogram, even at the current
level of development (NASA nuclear power website, 2004).

**Table 7.** ANTS Architecture Progression in Power Requirements

Application Time System Power Mass Power Subsystem/System

Lander Amorphous Rover Antenna 2015 EMS \<100 Watts \<10 kg/50 kg\
Prospecting Asteroid Mission 2025 MEMS (10^-2^ EMS) \<1 Watts \<0.5 kg/1
kg\
Saturn Autonomous Ring Array 2035 NEMS (10^-4^ EMS) \<100mWatts 0.1 kg/1
kg

There is an additional incentive for the use of RPS technology. The
availability and utility of nuclear battery technology is being improved
by the development of MEMS level designs, currently being tested, and
NEMS level concepts (e.g., Johnson, 2002).Tiny MEMS batteries,
long-lasting and with efficient thermoelectric conversion mechanisms
generating small increments of power (micro-amps), could be embedded
into ANTS structures where needed. This technology should be available
for future ANTS applications which allow considerably smaller mass
budgets, perhaps tenths of a kilogram, for the power subsystem, but
still need to generate hundreds of milliwatts. For PAM and SARA, the
smaller power generation requirement met by EMS RHU-based systems is not
well correlated with required mass.

# conclusions

The current capability of generating hundreds of milliwatts per kilogram
puts it 'within the ballpark' of ANTS requirements at the current
ART/EMS level of development. Anticipated improvement in the thermal
output and relatively inefficient thermoelectric conversion rate by at
least half an order of magnitude are highly desirable and necessary for
more advanced ANTS applications. The efficiency of conversion in the
MEMS nuclear batteries under development (Johnson, 2002) could
potentially meet this requirement. Improvements in the current power
output to weight ratio by a factor of ten would be ideal for future ANTS
applications.

# nomenclature

ANTS = Autonomous NanoTechnology Swarm Space Architecture

ART = Autonomous Reconfigurable Technology (EMS)

MART = Miniaturized ART (MEMS)

SMART = Super Miniaturized ART (NEMS)

EMS = Electro Mechanical Systems

MEMS = Micro Electro Mechanical Systems

NEMS = Nano Electro Mechanical Systems

PAM = ANTS Prospecting Asteroid Mission Concept

LARA = ANTS Lander Amorphous Rover Antenna Mission Concept

SARA = ANTS Saturn Autonomous Ring Array Mission Concept

TetWalker = 1, 4, 12, or many tetrahedra system used as ANTS rover

Node&Strut= deployment mechanism for ANTS structures: nodes apices,
struts sides of tetrahedra

# acknowledgments

We would like to acknowledge the important discussion pertaining to this
work we had with Robert Abelson and others at a NASA sponsored RPS
workshop at JPL earlier this year. We also appreciate contributions to
this work made by our students Jason Leggett, Richard Watson, Noah
Desch, Adrienne Davis, Tom Comberiate, and Jeff Lee. We thank NASA/GSFC
DDF, GSFC Codes 695, 544, and 588, and the RASC Program for their
support.

# references

ANTS website: http://ants.gsfc.nasa.gov

Clark, P.E., Iyengar, J., Rilee, M.L., Truszkowski, W., Curtis, S.A., A
conceptual framework for developing intelligent software agents as space
explorers [*Proceedings of the decision science institute*, 2002*,
*]{.smallcaps}(in press).

Clark, P.E., Curtis, S.A., Rilee, M.L., Truszkowski, W., Marr, G.,
Cheung, C.Y., and Rudisill, M., BEES for ANTS: Space Mission
Applications for the Autonomous NanoTechnology Swarm, AIAA Intelligent
Systems Technical Conference, Session 29-IS-13: ANTS, Chicago, Illinois
2004a.

Clark, P.E., Rilee, M.L., Curtis, S.A., Cheung, C.Y., Marr, G.,
Truszkowski, W., Rudisill, M., LARA: Near Term Reconfigurable concepts
and components for lunar exploration and exploitation, *IAC
Proceedings*, IAC-04-IAA.3.8.1.08, 2004b.

Clark, P.E., Rilee, M.L., Curtis, S.A., Cheung, C.Y., Marr, G.,
Truszkowski, W., Rudisill, M., PAM: Biologically inspired engineering
and exploration mission concept, components, and requirements for
asteroid population survey, *IAC Proceedings*, IAC-04-Q5.07, 2004c.

Clark, P.E., M.L. Rilee, S.A. Curtis, C.Y. CHeung, W.F. Truszkowski, In
Situ Surveying of Saturn\'s Rings, Lunar and Planetary Science 2004d.

Curtis, S.A., Mica, J., Nuth, J., Marr, G., Rilee, M.L., Bhat, M.,
Autonomous Nano-Technology Swarm. *Proceedings of the 51st International
Aeronautical Congress*, IAF-00-Q.5.08, 2000.

Curtis, S.A., Cheung, C.Y., Rilee, M.L., Clark, P.E., Truszkowski, W.,
Marr, G., Saturn Autonomous Ring Array, NASA RASC Proposal, 2003.

Curtis, S., Clark, P.E., Cheung, C.Y., Rilee, M.L., Truszkowski, W.,
Marr, G., The ANTS Mission Architecture and its application to the PAM
Mission, DRM (Final Report) for the RASC program, 2004a.

ESLI website: http://www.esli.com

Johnson, C., Radioisotopes fuel microscopic battery, EE Times, November
5, 2002, http://www.eetimes.com/article/
showArticle.jhtml?articleId=12805067

Mondt, J.F., Advanced radioisotope power systems requirements for
potential deep space missions, 2000, AIAA-2000-2880.

NASA nuclear power website,
http://spacescience.nasa.gov/missions/npsfactsheet.pdf, 2004.

PF website, http://www.meetingsmanagement.com/, polymer fibers, 2004.

President's Commission on Implementation of United States Space
Exploration Policy, June 2004.

Rilee, M.L., Curtis, S.A., Clark, P.E., Cheung, C.Y., Truszkowski, W.,
2004, An implementable pathway to SMART matter for adaptive structures,
IAC Proceedings, 2004a.

Rilee, M.L., Curtis, S.A., Clark, P.E., Cheung, C.Y., Truszkowski, W.F.,
2004, From buses to bodies: SMART matter for space systems applications,
IAC Proceedings, 2004b.