MISSION: Mars Exploration Rovers (MER-1/MER-2)

• LAUNCH VEHICLES: Delta II/Delta II Heavy
• LAUNCH PADS: 17-A/17-B
• LAUNCH DATES: June 6/June 25
• LAUNCH TIMES: 2:12:44 p.m. / 12:38:16 a.m. EDT

The beginning of the launch period for the first of NASA's two Mars Exploration Rover missions will be rescheduled until no earlier than June 6 to allow time to address a potential problem raised during pre-launch tests of the spacecraft over the weekend.

The concern regards cabling that connects the spacecraft's main computer, which is inside the rover, to peripherals in the cruise stage, lander and small deep space transponder. The connection to the cruise stage is severed during approach to Mars and the connection to the lander is severed before the rover drives off. Pre-launch testing revealed a potential problem in how the spacecraft interprets signals sent when the cables are severed. The problem will require fixing on both rovers. The work is not expected to effect the launch period for the second rover mission which is scheduled to open June 25 and close July 15 for a landing Jan. 25, 2004. However, the second mission cannot launch until 10 days after the first one.

The remedy will require some disassembly of the spacecraft at NASA's Kennedy Space Center, Cape Canaveral, Fla. The work cannot be done within the schedule of preparations for the original May 30 opening of the launch period. The mission will have two launch opportunities each day during the launch period, which is scheduled to close on June 19. Arrival at Mars is set for Jan. 4, 2003, regardless of launch date within that period.

On Cape Canaveral Air Force Station, first and second stage processing activities for the MER-A vehicle continues in Hangar AO and erection on Pad 17-A is planned to begin April 22. Erection of the vehicle for MER-B is planned to begin May 24.

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