Mars Exploration Rovers (MER-1/MER-2) Launch Status 14 Apr 2003

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.