Deployment and egress of the Mars Rovers will take a number of sols and
involve many decisions by scientists and engineers. The process begins
after the airbags roll to a stop.
The MER lander is in the shape of a tetrahedron. Its four sides are
called petals. The airbags retract as they slowly deflate, and the
latches that hold the lander petals together are released. Airbag
retraction may take as long as an hour and a half.
After the airbags retract, the lander petals open.
The rover is locked down to one petal – the base petal. The lander may
not come to rest on the base petal, so the action of opening the petal
the lander rests on pushes the lander, and rover, right side up.
The fabric ramps between the lander petals (called egress aids) are
deployed automatically as the petals open.
Full lander petal deployment can take anywhere from 30 minutes to an
hour. Once the lander is open, it reveals a tightly folded rover.
Then the secondary solar panels are deployed.
The Pancam Mast Assembly rises from its locked position against the
rover’s solar panel deck.
The High Gain Antenna is deployed. Now communications can occur at
higher transmission rates. The Navcam takes a panoramic image so that
engineers can assess the terrain around the rover for egress.
It may take several sols to fully deploy the rover. Scientists and
engineers want to make sure that each command has been executed properly
before they proceed to the next.
One sol may focus on rover stand-up. At around the same time,
360-degree panoramas are taken by Pancam and Mini-TES.
In another sol, the ties that hold the rover to the lander are cut and
if necessary the rover is commanded to turn in the selected egress
The rover is commanded to drive off the lander in the direction that
looks the safest. Many Navcam and Hazcam images are taken to determine
which way is best.
Once engineers are certain the rover has completed a successful egress
from the lander, surface operations can begin.