Sojourner Truth
Ares Vallis
MARS

July 12, 1997

Dear Mom,

Yogi and I bought ourselves yet a little more time together by begging Carl to reset his computers again. Here's a quote from the Earth Team, Mom:

The flight team received a signal from the Pathfinder lander's low-gain antenna at 6:45 p.m. Friday confirming that the lander (Carl) received Friday's commands and was beginning to execute them. The team then expected to receive data over the lander's high-gain antenna beginning at 8:45 p.m. However, no signal was received at that time.

The team then sent a command to the lander via its low-gain antenna at about 9:45 p.m. instructing the lander to send a signal back to Earth. This signal was received. Flight controllers concluded that the lander's computer must have reset itself sometime between 6:47 and 8:47 p.m. PDT Friday evening. The commands to move the rover would not have been executed, because they were scheduled to take place later.

Commands were then sent at about 11:00 p.m. instructing the lander to point its high-gain antenna at Earth and begin a half-hour downlink session sending engineering data reporting on the status of the lander and rover. Commands were also sent to back the rover away from Yogi. Another command instructed the lander to take and transmit an image of the rover confirming that the repositioning had been completed.

At 12:15 a.m. PDT, the Deep Space network station near Canberra, Australia, acquired a signal from the pathfinder lander at the beginning of a half-hour downlink session sent via the lander's high-gain antenna. Data sent during this session indicated that the rover did in fact receive and execute commands to back it away from the Yogi rock and reposition itself on Thursday. It reexecuted these commands when they were resent Friday. In addition, an image was received at about 12:25 a.m. which showed the rover backed away from Yogi.

Friday evening marks the second time that the Pathfinder lander's computer has reset itself since its landing July 4. The flight team is not certain why the resets are taking place, but engineers noted that both incidents occurred during periods of heavy communication between the lander and rover.

:-)

Love,

S.T.