A full-scale replica of the Phoenix Mars Lander at JPL.
As I write this, mission controllers at NASA’s Jet Propulsion Laboratory and Lockheed Martin’s Mission Support Area in Colorado have just decided not to make one final tweak to the course trajectory of the Phoenix Mars Lander in its final approach to the Red Planet.
The spacecraft is aimed at a roughly 60 miles long landing ellipse high in the Martian arctic regions around 68 degrees north. This area is of particular interest as it is covered in carbon dioxide during the northern winter, and in summer is an area of exposed permafrost. If Phoenix survives the landing intact and is able to function it will use a robotic arm to dig a trench and retrieve Martian ice - becoming the first spacecraft to ‘touch’ water in the act of searching for complex organic molecules.However mission planners were concerned the final navigational data was showing a slight tendency to drift out of the center of the ellipse. This triggered the debate over a final trajectory correction maneuver (TCM).
The blue circle is the ideal landing ellipse and the magenta circle is the approximate zone within which the spacecraft will land on its current course. If the magenta circle goes outside the '+' mark in the center that would signal a definite TCM, says NASA and Lockheed Martin.
One more TCM opportunity for a last-minute course correction still exists at 8.46am PST tomorrow but most believe no further action will be required unless the entry into the Martian gravity well provides unexpected surprises.
Further updates on the final few hours towards the landing will be provided on this blog and tomorrow evening on the Aviation Week & Space Technology website from JPL where senior editor Craig Covault and myself will be monitoring events. Phoenix is expected to enter the Martian atmosphere at 4.46pm tomorrow and touchdown 9 minutes later, although confirmation of a safe landing depends on a brief 60-sec worth of relay time provided by the US Mars Odyssey and Reconnaissance orbiters which are on duty to monitor the nail-biting event.