Status Report

Orbital Express Demonstration Program March 14, 2007

By SpaceRef Editor
March 28, 2007
Filed under ,

The Defense Advanced Research Projects Agency (DARPA) Orbital Express program will
validate the technical feasibility of robotic, autonomous on-orbit refueling and reconfiguration of
satellites during a three-month demonstration mission that began on March 8, 2007.

The Orbital Express demonstration consists of a pair of satellites, the ASTRO servicing vehicle
and the NextSat demonstration client vehicle. The two experimental satellites were successfully
launched into their desired orbit as a mated pair on an Atlas V launch vehicle from Cape
Canaveral on the evening of March 8.

Following release from the Centaur upper stage, the Orbital Express ASTRO vehicle experienced
a guidance anomaly during initialization. The ASTRO spacecraft responded to this problem by
attempting to achieve a sun-safe attitude (with the mated pair of spacecraft maintaining a position
with their solar arrays pointing toward the sun), but the guidance error prevented the system from
achieving a proper sun-safe attitude. To correct for this problem, control of the mated pair was
shifted from ASTRO to NextSat and the Orbital Express team used NextSat’s guidance system to
successfully point the mated stack towards the sun.

NextSat continued to control the stack while the Orbital Express team worked to determine the
root cause of the problems experienced during initialization and sun-safe pointing. The team has
uploaded a software fix to correct the anomaly and successfully tested ASTRO’s sun-safe mode
on March 13.

ASTRO and NextSat are both currently in a sun-safe attitude, and the Orbital Express team will
resume the originally planned checkout and mission operations early next week.

SpaceRef staff editor.