WRAL WeatherCenter Blog

Curiosity settles into her new home

Posted August 22, 2012

Curiosity survived the seven minutes of terror two weeks ago, landing safely along side Gale Crater near Mars' equator. Since then, cameras and other instruments have been validated. Software has been changed over from cruise phase to roving phase. The mast has been raised, the arm extended and cameras are being tested and have already returned exciting images.

The laser has been put through its paces, zapping a first geological victim, a small stone now known as coronation rock.

Most recently the rover drivers wiggled the right rear wheel to verify the rover is ready to roll. That first test drive is expected Wednesday.

So far the only problem that has been found is located in the rover's onboard weather station. Wind sensors sustained some damage, possibly from small rocks kicked up during the landing. Engineers are already on the problem and are confident that workarounds can be developed to restore as much functionality as possible. If a bunch of guys in crewcuts can get the stricken Apollo 13 and her crew home safely, this problem should be a piece of cake for "mohawk guy."

The rest of the weather station is already transmitting data back to Earth, confirming what scientists expected: It's chilly on Mars.

Weather data received late last week showed a high of 28°F around local noon. The low of -103°F happened around 2 a.m. local time with ground temperatures nearly 30 degrees colder. Pressure readings also vary daily from 6.9 to 7.8 millibars. For comparison, the barometric pressure at RDU yesterday varied between 1014.8 and 1018.3 millibars. Not only is it cold, but the Martian atmosphere is also quite thin as compared to what we have here.

Each night, the rover pauses to transmit data back to Earth, receive marching orders for the next day and to recharge batteries from the onboard nuclear plant. Nearly half that power is directed to onboard heaters that keep computers, scientific instruments and other equipment sufficiently warm.

Throughout its mission, Curiosity will continue to feed weather data back to Earth. In addition to what we call weather – temperatures, winds and so on, space weather affects Mars even more that Earth. Curiosity's Radiation Assessment Detector (RAD) was enabled during its cruise from Earth to Mars showing the impact of solar flares and other solar activity. RAD will be used on the surface to gather long-term data on the radiation exposure future missions, including manned ones, can expect.

Tony Rice is a volunteer in the NASA/JPL Solar System Ambassador program and software engineer at Cisco Systems. You can follow him on twitter @rtphokie.


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  • nsj Aug 23, 2012

    Regarding 2, it's mostly an issue of the atmosphere, or lack of much of one. The atmosphere on Mars is quite thin (Curiosity is measuring atmospheric pressures less than 1% than what we have here on earth). Without much of an atmosphere, there is nothing to "buffer" the heat from the sun. So, during the day, things heat up rapidly, but at night, that heat escapes back out to space quite efficiently.

  • Tony Rice Aug 23, 2012

    You are right to label these curiosities.
    1) The Mars atmosphere is very cold and very thin so it can't hold much water vapor. So it can be thought of as very dry. It's interesting you bring up relative humidity. That atmosphere, at least in the lower levels, is holding about as much moisture as it can at that pressure and temperature. So the relative humidity is very high. Fog has been seen in lower elevations as far back as the Viking missions in the 70's. Here's an image where some fog is visible from one of the orbiters http://www.space.com/2268-images-mars-orbiter-high-resolution-camera-wow-researchers.html Originally, that fog was thought to be CO2 based but more data comes from orbiters, landers and rovers, particularly temperature readings, the view has switched to water ice as the source.

    2) I'm no meteorologist so I'll leave the real answer to your 2nd question to Nate, Greg, Elizabeth, Aimee or one of the Mikes.

  • ibio001 Aug 23, 2012

    A couple of curiosities:

    1) The presence of water has been theorized – is there *ever* a relative humidity (or other water vapor measure) reading > 0, such as when condensation occurs with temperature changes?
    2) What accounts for the variability in day-to-day temperature differences? The temperature graphs are markedly similar but not identical at the same times across two days. There is no cloud cover and presumably insufficient moisture (differences). Is it the changing length of the day? Reading variability due to changes in Curiosity positioning/activity?