TAU (Thousand Astronomical Unit) mission
An interstellar precursor mission concept, studied
by JPL scientists in the late 1980s, with the potential for enabling an
unmanned probe to reach a distance of 1,000 astronomical
units (AU) (0.016 light years) within a 50-year trip time. TAU would
be powered by a nuclear reactor in the 1-MWe class with a specific mass
of 12.5 kg/kWe and a full-power operating (thrusting) time of 10 years.
RTG power supplies would provide power for the science instruments for the
40-year cruise portion of the mission (after reactor and propulsion system
burn-out and jettison). The electric thrusters required would have a specific
impulse (Isp of 10,000-20,000 lbf-s/lbm) and a burn
time (per thruster) of 2 years, as might be available from advanced
ion thrusters. The propellant would be xenon
(see XIPS). The propulsion system (ion thrusters,
power processor units, etc.) specific mass would be 4 kg/kWe.
| Diagram of one possible configuration
The primary science objective of the mission is to measure directly the
distance to stars throughout our galaxy using stellar parallax.
Secondary science objectives include particles and fields measurements,
a search for the heliopause, a search
for the Oort Cloud, tests of gravitational
effects based on changes to the spacecraft's trajectory (which could be
caused by a tenth planet or other "dark" companions of the solar system),
and tests of general relativity (such as
using the optical communications link with the spacecraft as a long-baseline
gravity wave detector).
AND SPACE PROBES