An error in the star tracking system aboard Deep Space 1, NASA's first New Millennium programme spacecraft, forced the craft to enter a "safe mode" shutdown on 13 November. Engineers brought it back to normal cruise configuration 48h later.

Devices to control the deployment of the craft's solar arrays were also activated unexpectedly during the shutdown procedure.

The shutdown was a new problem for NASA following earlier closure of the ion propulsion system. Further attempts to restart the system are planned following its premature shutdown after just 4.5s on 10 November.

Ground controllers failed to restart the engine immediately. The engine is expected to propel the Deep Space 1 towards a rendezvous with the asteroid 1992 KD in July 1999.

NASA, meanwhile, has selected five candidate proposals for assessment to fly the seventh and eighth low-cost Discovery programme series missions. In addition, and as part of the Discovery programme, NASA will fund a US co-investigator instrument to fly piggyback on a Swedish experiment to study the solar wind and atmosphere of Mars during the European Space Agency's Mars Express mission.

The five Discovery candidate missions are: Aladdin, to gather tiny samples of the Martian moons Deimos and Phobos and return them to earth; Deep Impact, a mission to fly a projectile into the comet P/Tempel 1; Inside, a Jupiter orbiter to fly within the atmosphere of the giant planet; Messenger, a Mercury orbiter; and Vesper, a Venus orbiting spacecraft.

NASA will select one or two of these proposals in June 1999. The first Discovery missions included the Mars Pathfinder - originally part of a Mars surface environment programme and which was incorporated into the Mars Surveyor programme, landing on Mars in 1997 - and the Lunar Prospector orbiter, launched in January.

Two other Discovery missions are the Near Earth Asteroid Rendezvous - the first Discovery mission to be launched - which is due to arrive in orbit around asteroid Eros on 10 January 1999; and the Stardust, which will be launched on 6 February. The fifth and sixth missions are the Comet Nucleus Tour and Genesis, a craft to collect samples of solar wind.

Source: Flight International