The Mars Descent Imager (MARDI) was intended to take pictures of the landing site during the last three minutes of descent.
As originally planned, it would have begun taking pictures after the aeroshell departed, about 8 km above the Martian soil.
Before launch, testing of the assembled spacecraft uncovered a potential data corruption problem with an interface card that was designed to route MARDI image data as well as data from various other parts of the spacecraft.
The potential problem could occur if the interface card were to receive a MARDI picture during a critical phase of the spacecraft's final descent, at which point data from the spacecraft's Inertial Measurement Unit could have been lost; this data was critical to controlling the descent and landing.
This was judged to be an unacceptable risk, and it was decided to not use MARDI during the mission.
As the flaw was discovered too late for repairs, the camera remained installed on Phoenix but it was not used to take pictures, nor was its built-in microphone used.

MARDI images had been intended to help pinpoint exactly where the lander landed, and possibly help find potential science targets.
It was also to be used to learn if the area where the lander lands is typical of the surrounding terrain.
MARDI was built by Malin Space Science Systems.
It would have used only 3 watts of power during the imaging process, less than most other space cameras.
It had originally been designed and built to perform the same function on the Mars Surveyor 2001 Lander mission; after that mission was canceled, MARDI spent several years in storage until it was deployed on the Phoenix lander.
The Mars Descent Imager (MARDI) was intended to take pictures of the landing site during the last three minutes of descent. As originally planned, it would have begun taking pictures after the aeroshell departed, about 8 km above the Martian soil. Before launch, testing of the assembled spacecraft uncovered a potential data corruption problem with an interface card that was designed to route MARDI image data as well as data from various other parts of the spacecraft. The potential problem could occur if the interface card were to receive a MARDI picture during a critical phase of the spacecraft's final descent, at which point data from the spacecraft's Inertial Measurement Unit could have been lost; this data was critical to controlling the descent and landing. This was judged to be an unacceptable risk, and it was decided to not use MARDI during the mission. As the flaw was discovered too late for repairs, the camera remained installed on Phoenix but it was not used to take pictures, nor was its built-in microphone used.
MARDI images had been intended to help pinpoint exactly where the lander landed, and possibly help find potential science targets. It was also to be used to learn if the area where the lander lands is typical of the surrounding terrain. MARDI was built by Malin Space Science Systems. It would have used only 3 watts of power during the imaging process, less than most other space cameras. It had originally been designed and built to perform the same function on the Mars Surveyor 2001 Lander mission; after that mission was canceled, MARDI spent several years in storage until it was deployed on the Phoenix lander.
Phoenix (spacecraft)