Mars Lander Team Applies for Mission Extension Posted on July 24th
NASA’s
Phoenix Mars Lander might be digging up the surface of the red planet for
longer than expected. Mission controllers have requested an extension to the
spacecraft’s work on the planet’s surface, SPACE.com has learned.
The $420
million mission has been investigating the dirt and ice of the northern reaches
of Mars since it landed
on May 25. The mission was slated to last for 90 sols, or Martian days
(about 92 Earth days), ending at the end of August. Now it could be extended
another 30 sols.
Because of
the landing spot in the north polar region, the mission can’t continue forever.
Phoenix uses its two-wing solar array to convert sunlight into electricity to
power its instruments, storing some power in a pair of rechargeable batteries. However,
Phoenix’s landing site is above Mars’ Arctic Circle, so the sun isn’t up
during the whole Martian year and there eventually will be too little sunlight
to power the instruments. (The sun is above the horizon all summer, then begins
to set below the horizon come fall as it sets for the entire winter just as
the sun does above the Arctic Circle on Earth.)
But with
the success of the mission so far, and indications that Phoenix will be able to
keep going until the arctic region plunges into the long darkness of winter,
mission scientists want to keep going.
“We
think that there’s enough energy to continue digging and delivery to
instruments through at least 120 sols, and then after that, our energy starts
to go down, but we can still do operations as a weather station,” said Phoenix robotic arm co-investigator Ray Arvidson of Washington University in St. Louis.
Dig this
Phoenix has
been digging up samples of Martian dirt and the rock-hard
ice layer that lies underneath for testing in its onboard instruments to
determine their composition and look for signs that Mars may have been
habitable at some point in its past.
If the team
gets permission to extend the mission, they’ll likely have at least another 30
days of digging, Arvidson told SPACE.com, adding that the team will
“try to dig as long as we can and the resources permit.”
Phoenix will also use it stereo camera,
lidar instrument and other meteorological instruments to photograph the surface
and make measurements of the Martian weather.
But these
plans are “all predicated on permission to have an extended mission and
finances, so that’s all being negotiated right now with NASA
headquarters,” Arvidson said. He didn’t know when NASA might decide
whether or not to extend the mission.
The
missions of NASA’s Mars Exploration Rovers, Spirit and Opportunity, have also
lasted longer than originally anticipated. The primary missions for each rover
lasted for 90 days in 2003. The rovers are still trundling around the Martian
surface more than four years later, thanks to dust storms that cleared dust off
the vehicles’ solar panels.
What
about next year?
In
November, Mars dips behind the sun and out of our view, but will eventually
re-emerge. “Hopefully we’ll still be alive after that,” Arvidson said
of Phoenix, so that the lander can continue making a few last measurements, if
the extension plan is approved.
The setting
Martian sun will gradually diminish the amount of energy available to Phoenix
via its solar panels. ) As the sun sets and winter approaches, the temperature
at Phoenix’s landing site will start dropping and carbon dioxide ice will
precipitate out of the atmosphere.
“As
the seasons move from fall to winter on Mars
it’s something like 20 to 30
centimeters [about 8 to 12 inches] of CO2 ice forms out of the atmosphere,”
Arvidson said.
The colder
winter temperatures and carbon dioxide ice accumulating on the spacecraft will
ultimately spell its end, because the craft is not built to withstand these
frigid conditions. Phoenix won’t rise from the ashes when the sun comes up
again in the Martian spring.