RACE
Rubidium Atomic Clock Experiment

 
RACE, the Rubidium Atomic Clock Experiment, is a mission designed to extend the understanding of physical effects on atomic clocks to a fractional accuracy of 10-17 and vastly improve classic clock tests of Einstein’s theory of general relativity.  A laser-cooled atomic clock based on the ground-state hyperfine splitting in 87Rb will be flown on the International Space Station (ISS) and compared to a laser-cooled rubidium clock on the ground, as well as other clocks worldwide.  The long atom-interrogation times allowed by the microgravity environment make possible greater accuracy for laser-cooled clocks with high short-term stability as compared to their earth-bound counterparts. The use of 87Rb reduces the collision shift by a factor of 30 over a similar cesium instrument, allowing greater stability and accuracy.  There are currently three other clock experiments planned for the ISS: PARCS, ACES, and SUMO.  PARCS is a NASA mission and will fly a high performance Cs clock circa 2005.  ACES is an ensemble of clocks, including a laser cooled cesium, and a hydrogen maser, and is an ESA experiment expected to fly on the ISS in 2004.  SUMO is a superconducting cavity oscillator clock, and a NASA experiment scheduled to launch in early 2008, for simultaneous operation with RACE on the ISS.  Each of the three experiments will establish new scientific findings, and technological advances related to clocks.  RACE represents an advanced clock experiment to complement and extend the goals of science and technology established by its ISS predecessors.   We have three primary goals:

1) Advance atomic clock science and techniques to enable measurements with accuracies of 1 part in 10-17.
2) Significantly improve the classic clock tests of general relativity.
3) Distribute the highest achievable time and frequency stability accuracy from the ISS.
RACE has already passed the Science Concept Review and is now preparing for the Requirements Design Review with a planned launch date in early 2008.

Here are some slides from recent talks.
RACE is a joint effort between our group at Penn State and Lute Maleki's group at JPL.
Penn State Personnel:
Chad Fertig
Ruoxin Li
J. Irfon Rees
Kurt Gibble - PI		 JPL Personnel:
John Prestage - Project Scientist
Bill Klipstein
Rob Thompson
David Seidel - Project Manager
Support from thethe NASAMicrogravity Program