[meteorite-list] NASA's Hibernating Mars Rover May Not Call Home

[Ron Baalke]

July 30, 2010

J.D. Harrington 
Headquarters, Washington 
202-358-5241 
j.d.harrington at nasa.gov 

Guy Webster 
Jet Propulsion Laboratory, Pasadena, Calif. 
818-354-6278 
guy.webster at jpl.nasa.gov 

RELEASE: 10-182

NASA'S HIBERNATING MARS ROVER MAY NOT CALL HOME

WASHINGTON -- NASA mission controllers have not heard from the Mars 
Exploration Rover Spirit since March 22, and the rover is facing its 
toughest challenge yet -- trying to survive the harsh Martian winter. 

The rover team anticipated Spirit would go into a low-power 
"hibernation" mode since the rover was not able to get to a favorable 
slope for its fourth Martian winter, which runs from May through 
November. The low angle of sunlight during these months limits the 
power generated from the rover's solar panels. During hibernation, 
the rover suspends communications and other activities so available 
energy can be used to recharge and heat batteries, and to keep the 
mission clock running. 

On July 26, mission managers began using a paging technique called 
"sweep and beep" in an effort to communicate with Spirit. 

"Instead of just listening, we send commands to the rover to respond 
back to us with a communications beep," said John Callas, project 
manager for Spirit and Opportunity at NASA's Jet Propulsion 
Laboratory in Pasadena, Calif. "If the rover is awake and hears us, 
she will send us that beep." 

Based on models of Mars' weather and its effect on available power, 
mission managers believe that if Spirit responds, it most likely will 
be in the next few months. However, there is a very distinct 
possibility Spirit may never respond. 

"It will be the miracle from Mars if our beloved rover phones home," 
said Doug McCuistion, director of NASA's Mars Exploration Program in 
Washington. "It's never faced this type of severe condition before -- 
this is unknown territory." 

Because most of the rover's heaters were not being powered this 
winter, Spirit is likely experiencing its coldest internal 
temperatures yet -- minus 67 degrees Fahrenheit. During three 
previous Martian winters, Spirit communicated about once or twice a 
week with Earth and used its heaters to stay warm while parked on a 
sun-facing slope for the winter. As a result, the heaters were able 
to keep internal temperatures above minus 40 degrees Fahrenheit. 

Spirit is designed to wake up from its hibernation and communicate 
with Earth when its battery charge is adequate. But if the batteries 
have lost too much power, Spirit's clock may stop and lose track of 
time. The rover could still reawaken, but it would not know the time 
of day, a situation called a "mission-clock fault." Spirit would 
start a new timer to wake up every four hours and listen for a signal 
from Earth for 20 minutes of every hour while the sun is up. 

The earliest date the rover could generate enough power to send a beep 
to Earth was calculated to be around July 23. However, mission 
managers don't anticipate the batteries will charge adequately until 
late September to mid-October. It may be even later if the rover is 
in a mission-clock fault mode. If Spirit does wake up, mission 
managers will do a complete health check on the rover's instruments 
and electronics. 

Based on previous Martian winters, the rover team anticipates the 
increasing haziness in the sky over Spirit will offset longer 
daylight for the next two months. The amount of solar energy 
available to Spirit then will increase until the southern Mars summer 
solstice in March 2011. If we haven't heard from it by March, it is 
unlikely that we will ever hear from it. 

"This has been a long winter for Spirit, and a long wait for us," said 
Steve Squyres, the principal investigator for NASA's two rovers who 
is based at Cornell University. "Even if we never heard from Spirit 
again, I think her scientific legacy would be secure. But we're 
hopeful we will hear from her, and we're eager to get back to doing 
science with two rovers again." 

Spirit and its twin, Opportunity, began exploring Mars in January 2004 
on missions planned to last three months. Spirit has been nearly 
stationary since April 2009, while Opportunity is driving toward a 
large crater named Endeavour. Opportunity covered more distance in 
2009 than in any prior year. Both rovers have made important 
discoveries about wet environments on ancient Mars that may have been 
favorable for supporting microbial life. 

NASA's JPL manages the Mars Exploration Rover project for NASA's 
Science Mission Directorate in Washington. 

For more information about the rovers, visit: 

http://www.nasa.gov/rovers 
	
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