Editor's update: According to Doug McCuistion, Mars Exploration Program director, speaking at a press conference today regarding the potential problems with the MARDI instrument and testing of the Phoenix lander "It is important to remember that we bought a used car".
One Image Planned During Descent of Phoenix , NASA JPL
"The issue is not the camera itself, which is capable of taking multiple downward-looking images of the landing area during the final three minutes of flight. Tests of the assembled lander found that an interface card has a small possibility of triggering loss of some vital engineering data if it receives imaging data during a critical phase of final descent. That possibility is considered an unacceptable risk, and the potential problem with the interface card was identified too late for changing hardware. The card has circuitry that routes data from various parts of the payload."
Editor's note: Although NASA and all of the mission participants are very shy about saying this, Phoenix was originally called the Mars Surveyor 2001 lander - a spacecraft with significant hardware commonality with the Mars Polar Lander. As you may recall, MPL crashed into Mars when the jolt of its engines firing made some sensors think the spacecraft had landed - so it shut the engines off - and ... splat. The main culprit was found to be incomplete integrated testing prior to launch.
It's great that they did more integrated testing this time, but I have to wonder why they waited to test such things in an integrated fashion where results from that testing could not result in a hardware fix, but rather not using part of the spacecraft's hardware - thus diminishing its capability.
And although the "science" won't be affected once Phoenix is on the surface, this is a case where the spacecraft's overall objectives will not be met - despite the spin NASA is trying to put on it. Otherwise, why was a descent imager capable of multiple images included on the spacecraft in the first place?
But wait - NASA/JPL is saying that "the mission will still be capable of accomplishing all of its science goals."
I am confused. This mission fact sheet at the University of Arizona says: "Mars Descent Imager (MARDI) - Built by Malin Space Science Systems MARDI plays a key science role during Phoenix's descent to the Martian arctic. Beginning just after the aeroshell is jettisoned at an altitude of about 5 miles, MARDI will acquire a series of wide-angle, color images of the landing site all the way down to the surface."
And further, this page at Malin Space Science Systems says "The Phoenix Mars Descent Imager (MARDI) will provide a context in which all other Phoenix observations can be fully understood. Among the most important questions to be asked about a spacecraft sitting on a planet is "Where is it?" and "Descent imaging provides a bridge between orbiter pictures, that tell us about regional and global scales, and lander images of very small, "micro-scale" attributes of the planet."
So what is it, NASA? Does this instrument play a key "science role" in this mission or doesn't it? You really need to be consistent with what you've said previously before you try and spin bad news into something a little more palatable.
Editor's update: Malin Space Science Systems was issued a stop work order on MARDI effective 1 June 2007.