AAWSAP DIRD, Laser Lightcraft Nanosatellites, November 2010

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Chapter 1: Nanosatellite Technologies
OVERVIEW
Nanosats require technologies that radically reduce the mass and power of components
without compromising performance. In addition to miniaturizing components, methods
to integrate similar functions across subsystems are being evaluated. For example, all
subsystem electronics, including instruments, could be integrated within the Command
and Data Handling (C&DH) subsystem. Multifunctional solutions also offer significant
savings over traditional approaches. Technology investments are required to develop
or adapt components to accommodate the expected radiation environment. Simple,
effective methods of thermal control are essential to keep the nanosat operational
during extreme temperature variations. Autonomy is a critical technology that impacts
every subsystem. Constellations with tens to thousands of nanosats must be highly
autonomous to be practical. The nanosat ground system must be kept inexpensive,
simple, and made inter-operable with other missions.
PROPULSION
In the baseline mission, nanosat propulsion is needed for two distinct functions: 1) each
nanosat must raise its orbit apogee to the appropriate radius, 2) and it must reorient
the axis of the spinning nanosat from the velocity direction (within the orbit plane) to
its science mission attitude (perpendicular to the ecliptic plane). These maneuvers
present challenging velocity change (1W) and attitude-control (ACS) requirements.
Requirements for the Av Thruster:
•
Total impulse: 3,000 to 7,000 N-sec.
•
Thrust: 445 N maximum.
•
Input power (during burn): < 1 watt.
•
Specific impulse: 280 seconds.
Requirements for the ACS Thruster:
•
Total impulse: $ 2.4 N-sec.
•
Minimum impulse bit: 0.044 N-sec.
•
Response time: < 0.005 sec.
•
Pulse rate: 1 Hz.
It turns out that the tiv and ACS thrusters can have independent systems. We propose
a new innovation whereby the nanosat launch vehicle propulsion system also serves
double duty as the tiv thruster system, and this can be done without having to carry the
propulsion energy source into orbit. This can only be achieved via laser propulsion in
which the laser beam energy that is used to launch a nanosat into orbit is also used to
provide tiv thrust in orbit. This novel innovation dramatically reduces the mass, size,
cost, and complexity of nanosats because they will only need to carry minimal onboard
ACS thrusters and propellant to carry out routine, minor attitude adjustments. The
innovative nanosat laser propulsion concept is presented in Chapter 2.
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