• Blog Stats

    • 1,223,946 hits

Phoenix: The Far Lady isn’t singing yet…

,,, but she’s definitely tuning up in the wings…

A very important email from NASA dropped into my email box earlier tonight…

In a race against time and the elements, engineers with NASA’s Phoenix Mars Lander mission hope to extend the lander’s survival by gradually shutting down some of its instruments and heaters, starting today.

Originally scheduled to last 90 days, Phoenix has completed a fifth month of exploration in the Martian arctic. As expected, with the Martian northern hemisphere shifting from summer to fall, the lander is generating less power due to shorter days and fewer hours of sunlight reaching its solar panels. At the same time, the spacecraft requires more power to run several survival heaters that allow it to operate even as temperatures decline.

“If we did nothing, it wouldn’t be long before the power needed to operate the spacecraft would exceed the amount of power it generates on a daily basis,” said Phoenix Project Manager Barry Goldstein of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “By turning off some heaters and instruments, we can extend the life of the lander by several weeks and still conduct some science.”

Over the next several weeks, four survival heaters will be shut down, one at a time, in an effort to conserve power. The heaters serve the purpose of keeping the electronics within tested survivable limits. As each heater is disabled, some of the instruments are also expected to cease operations. The energy saved is intended to power the lander’s main camera and meteorological instruments until the very end of the mission.
 
Later today, engineers will send commands to disable the first heater. That heater warms Phoenix’s robotic arm, robotic-arm camera, and thermal and evolved-gas analyzer (TEGA), an instrument that bakes and sniffs Martian soil to assess volatile ingredients. Shutting down this heater is expected to save 250 watt-hours of power per Martian day.

The Phoenix team has parked the robotic arm on a representative patch of Martian soil. No additional soil samples will be gathered. The thermal and electrical-conductivity probe (TECP), located on the wrist of the arm, has been inserted into the soil and will continue to measure soil temperature and conductivity, along with atmospheric humidity near the surface. The probe does not need a heater to operate and should continue to send back data for weeks.

Throughout the mission, the lander’s robotic arm successfully dug and scraped Martian soil and delivered it to the onboard laboratories. “We turn off this workhorse with the knowledge that it has far exceeded expectations and conducted every operation asked of it,” said Ray Arvidson, the robotic arm’s co-investigator, and a professor at Washington University, St. Louis.

When power levels necessitate further action, Phoenix engineers will disable a second heater, which serves the lander’s pyrotechnic initiation unit. The unit hasn’t been used since landing, and disabling its heater is expected to add four to five days to the mission’s lifetime. Following that step, engineers would disable a third heater, which warms Phoenix’s main camera — the Surface Stereo Imager –and the meteorological suite of instruments. Electronics that operate the meteorological instruments should generate enough heat on their own to keep most of those instruments and the camera functioning.
 
In the final step, Phoenix engineers may turn off a fourth heater — one of two survival heaters that warm the spacecraft and its batteries. This would leave one remaining survival heater to run out on its own. 

“At that point, Phoenix will be at the mercy of Mars,” said Chris Lewicki of JPL, lead mission manger.

Engineers are also preparing for solar conjunction, when the sun is directly between Earth and Mars. Between Nov. 28 and Dec. 13, Mars and the sun will be within two degrees of each other as seen from Earth, blocking radio transmission between the spacecraft and Earth. During that time, no commands will be sent to Phoenix, but daily downlinks from Phoenix will continue through NASA’s Odyssey and Mars Reconnaissance orbiters.  At this time, controllers can’t predict whether the fourth heater would be disabled before or after conjunction.

What does that mean, exactly? Well, it means that if Phoenix was standing near a wall, she could swivel her camera mast around and photograph the writing on it… and that writing would read “The End Is Nigh.” It means that Phoenix’s controllers will soon have to start turning bits off to save energy, in an effort to keep the lander alive a little longer, just a little bit longer…

This isn’t a surprise, or a shock, of course. Unlike the Mars Exploration Rovers – which many of us now have come to believe are immortal – Phoenix simply can’t keep going, and going and going like a Duracell bunny. Phoenix feeds on solar energy, and now, with the Sun setting earlier each day, the sky darkening and the temperature plummeting, that energy is starting to get harder and harder to find. Frost is forming on the ground around Phoenix, and on Phoenix herself. She’s getting colder and colder as she stands there, looking out over that endless arctic plain, and now, as her heaters are turned off one by one, an awful, aching, penetrating cold will start to gnaw away at her like a vulture. She’ll slow down, start to get drowsy, and will be able to see, and do, less and less each day. She’ll find it harder to take pictures, even harder to talk to Earth, and will basically start to fail. Which is very sad, but we all knew it was going to happen; we all knew that her landing site up near the martian north pole would be her grave before year’s end, and that every sol past #90 would be a bonus. Today is sol 151, so she’s already lasted two months longer than her design called for her to, so even if she died the very moment you stopped reading this she would have been a remarkable success…

…and yet… and yet…

Oh how we want her to survive a while longer! Greedily, selfishly, we want more wonderful pictures of trenches, the far away horizon and the polygon-embroidered ground around her. We want to see more fantastic footage of clouds scudding across the sky; more close-ups of martian dust grains; more dust devils whirling and whorling across the landscape…

So, hang on in there Phoenix, there’s more to do yet, and a lot more to see, too.

Advertisements

3 Responses

  1. Solar energy for Phoenix does seem to also be her achilles heel. Good article but I too admit a bit of sadness to see her mission and life winding down. You are right though in that she has surpassed her mission objectives to say the least. A truly remarkable feat in such a cold and hostile place where she now rests.

    Ironic to think she operated on solar power and now that the end seems near the lack of such will be her demise…nonetheless truly remarkable use of solar power to begin with

  2. […] unable to move very soon. For more information, check these posts at the Planetary Society blog and Cumbrian Sky. Over the next several weeks, four survival heaters will be shut down, one at a time, in an effort […]

  3. Shadows are falling and I’ve been here all day
    It’s too hot [cold] to sleep time is running away
    Feel like my soul has turned into steel
    I’ve still got the scars that the sun didn’t heal
    There’s not even room enough to be anywhere
    It’s not dark yet, but it’s getting there

    – Bob Dylan, “Not Dark Yet”

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: