NASA gives Mars rovers five more months
By Dave Santucci
CNN Space Producer
(CNN) -- The manager of NASA's Mars missions said Thursday they have extended the working lives of Mars rovers Spirit and Opportunity until September and they could be extended even further.
Initially the missions were slated to last 90 days each, but with two healthy rovers returning regular information, the Mars rover project has been approved for a total of 250 days. That would prolong their missions until September 13.
Mars manager Firouz Naderi said if NASA has one or two healthy rovers come September, they may ask for another extension.
"This extended mission is bonus time ... it's gravy really," Naderi told reporters. He noted that Spirit has already met all of its primary mission objectives.
There are several factors that limit the life of the Mars rovers. First, martian dust continues to build up on the solar panels, limiting the power intake. Additionally, as time goes by and the seasons change on Mars, the sun is getting lower and lower on the horizon, cutting down the power the rover can draw from it.
Steve Squyres, the Mars rovers principal investigator, said the rovers' designers deemed the additional weight of adding wipers or blowers to the solar panels was not worthwhile. Instead they increased the size of the panels to maximize the power input.
The rovers' life spans also are limited by wear and tear. The motors can take only so many operations, especially in the extreme environment of Mars, and all of the components are subject to day and night cycles of extreme temperatures.
But Naderi maintained that everything has been tested to last 270 days.
Mars managers chose to extend the mission through September 13 because the rovers will be forced to take a break of about 10 days when communication with the rovers will be blocked by the sun.
After the extension was approved, Mars engineers took the opportunity this week to upload new software to both Spirit and Opportunity. The upgrades will improve three aspects of the rovers.
First, it is hoped new auto-navigation software will allow Spirit to travel 40 percent farther each day. Currently Spirit is in Gusev Crater, a very rocky terrain that is slowing progress significantly. The new software will allow the rover to make autonomous decisions about passing over potential hazards.
Spirit is headed for Columbia Hills, about a mile and half away, where scientists hope to find evidence Gusev Crater once held water.
The second software upgrade is designed to help reduce reboot time should Spirit experience another software glitch like it did on January 21. The glitch shut down the rover for several days, giving NASA a scare, but the problem was fully resolved and Spirit has been operating well ever since.
Third, a deep sleep command was added to Opportunity's software. The new mode will allow the rover to shut down a heater that has been stuck on and has been draining power.
Next week, once the four-day upload of the software is complete, Opportunity will head for Endurance crater, where scientists hope to find large outcroppings that can seek further evidence of the extent of the now-dry Martian ocean that the rover discovered in March.