Mission Timeline: Rover Egress Steps
Rover Egress Process
STEP ONE: Deploy the Pancam mast and the high-gain antenna
The last act of entry, descent, and landing and the beginning of egress is to initiate deployment of the Pancam Mast Assembly and the high-gain antenna. After the pancam mast assembly is deployed, a visual survey of the rover and the surrounding area is performed in preparation for the ground-directed adjustments leading up to rover egress.
STEP TWO: Characterize the lander, the landing site and the surrounding terrain
The lander and surrounding terrain is first imaged using the Hazcams. Navcam and Pancam panoramas are then taken. The combination of these images provides information regarding the deployment of the egress aids, the presence of airbag material or other debris on the lander petals , the height of the lander above the terrain, and the availability of viable egress paths from the lander. Note that the Navcam images have two blind spots that are obscured by the secondary solar arrays. In order for the ground to see viable backup egress paths, the rover needs to turn on the lander deck.
Once the images have been taken, the high-gain antenna is deployed to allow X-band direct to Earth (DTE) communications on the following day.
This deployment is followed by a determination of the sun´s position using the Pancam, which allows the Rover to determine its azimuth direction that is, to determine which way is north, south, east, and west. The rover shuts itself down (turns off its computer) until the next available UHF pass during which the EDL and deployment data are retransmitted.
STEP THREE: Rover stand-up
The automated standup sequence guides the deployment the rover rocker-bogie mobility system. In this sequence, a rover lift mechanism lifts the rover, allowing the rockers to be deployed. The lift mechanism then lowers the rover, and the bogies are deployed. Hazcam images are collected throughout this process to provide diagnostic data.
The Rover is now approximately 12 inches higher off of the Lander, and therefore has a better view of the surrounding terrain. Additional images of the martian landscape are then acquired for return to Earth.
STEP FOUR: Conduct calibration of the science instruments
The Calibration Campaign consists of all of the activities required to assess the health or initial state of the instruments and targets, and spans the period following completion of the rover critical deployments through the post-egress period. Some of the measurements function as post-landing health checks while other measurements serve as early baseline measurements that need to be taken before dust accumulates on the targets or magnets.
Red Rover Goes to Mars is a public outreach investigation that gives student representatives an opportunity to participate in a Mars mission in cooperation with the science team. The observational target for this activity is a DVD mounted on the lander deck in a location where a camera may image it, and includes a student magnet experiment.
Three imaging opportunities are available to image the DVD using either the Pancam or the Navcam. The first opportunity occurs during the pre-standup period. The second opportunity occurs during the Pancam mission success panorama that includes an image of the target.
One criterion for mission success is the return of two panoramic images. After rover standup, but prior to egress from the rover, the Pancam and Mini-TES acquire 360º panoramic images of the landing site. Other opportunities are available following egress to acquire this image; however, use of the pre-egress opportunity minimizes any risk arising from an anomalous egress.
STEP FIVE: Select a suitable egress path
Once the rover standup sequence is completed, the lander petals are adjusted to their final egress configurations and are hyper-extended, if necessary. The lander´s connection to the rover is then cut, and the rover is commanded to turn to the identified egress direction.
STEP SIX: Drive the rover onto the martian surface.
As the final step, the rover drives off of the lander deck onto the surface of Mars.
Once on the Mars surface, the rover begins its surface mission. At this point the lander is a lifeless shell, having served its purpose in protecting and delivering the rover.
Each rover uses a stereo pair of navigation cameras (Navcams) in addition to the panoramic cameras (Pancams) on the mast, to image prospective travel paths and science targets. Once the target objective is selected by the flight team, each six-wheeled rover travels to the selected target areas using an inertial measurement unit (IMU) and two lower sets of stereo hazard-avoidance cameras (Hazcams), mounted front and aft on the rover bodies under the solar panels. The Hazcam images supply data about the upcoming terrain to software onboard, which can autonomously navigate the rover to the selected area, or can stop to get updated instructions from Earth if conditions are unexpectedly challenging. The rover estimates its processing using the IMU data and wheel odometry to "dead reckon" when it has reached its destination.