AMSR-E Ends 9+ Years of Global Observations

October 4th, 2011 by Roy W. Spencer, Ph. D.


UPDATE #1: See update at end.

The Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) was automatically spun down to its designed 4 rpm safe condition last night after recent increases in the amount of power required to keep it spinning at its nominal 40 rpm were beginning to cause noticeable jitter in NASA’s Aqua satellite.

The instrument has over 480 pounds of spinning mass, and the lubricant in the bearing assembly gradually deteriorates over time. This deterioration has been monitored, and automatic shutdown procedures have been in place for years if the amount of torque required to keep AMSR-E spinning exceeded a certain threshold.

Starting about October 1, AMSR-E was causing yaw vibrations in the Aqua satellite attitude which were increasingly exceeding the +/- 25 arcsecond limits that are required by other instruments on the spacecraft. Last night, the 4.5 Newton-meter torque limit was apparently exceeded, and the instrument was automatically spun down to 4 rpm.

At this point it appears that this event likely ends the useful life of AMSR-E, which has been continuously gathering global data on a variety of parameters from sea ice to precipitation to sea surface temperature. It’s 9+ year lifetime exceeded its 6 year design life.

AMSR-E was provided to NASA by Japan’s Aerospace Exploration Agency (JAXA), and was built by Mitsubishi Electric Company. It was launched aboard the Aqua satellite from Vandenberg AFB on May 2, 2002. It has been an extremely successful experiment, and has gathered a huge quantity of data that will be revealing secrets of weather and climate as scientific research with the archived data continues in the coming years.

As the U.S. Science Team Leader for AMSR-E, I would like to congratulate and thank all of those who made AMSR-E such a success: JAXA, MELCO, NASA, the University of Alabama in Huntsville, the National Snow and Ice Data Center (NSIDC) in Boulder, and the U.S. and Japanese Science Teams who developed the algorithms that turned the raw data collected by AMSR-E into so many useful products.

The good news is that AMSR2, a slightly modified and improved version of AMSR-E, will be launched early next year on Japan’s GCOM-W satellite, and will join Aqua and the other satellites in NASA’s A-Train constellation of Earth observation satellites in their twice-daily, 1:30 a.m./p.m. sun-synchronous polar orbit. It is my understanding that those data will be shared in near-real time with U.S. agencies.

We had hoped that AMSR-E would provide at least one year over data overlap with the new AMSR2 instrument. It remains to be determined – and is only speculation on my part – whether there might be an attempt to gather some additional data from AMSR-E later to help fulfill this cross-calibration activity with AMSR2. [The Aqua satellite can easily accommodate the extra torque imparted to the spacecraft, and last night's spin-down of AMSR-E was mostly to eliminate the very slight chance of sudden failure of the AMSR-E bearing assembly which could have caused the Aqua satellite to go into an uncontrolled and unrecoverable tumble.]

Again, I want to thank and congratulate all of those who made AMSR-E such a huge success!

UPDATE #1: As of early this morning, the torque required to keep AMSR-E spinning at 4 rpm was too large for its own momentum compensation mechanism to handle, with excessive amounts of momentum being dumped to the spacecraft. As a result, the instrument has now been spun down to 0 rpm. The satellite has shed the excessive momentum, and is operating normally, as are the other instruments aboard the spacecraft (MODIS, CERES, and AIRS).


13 Responses to “AMSR-E Ends 9+ Years of Global Observations”

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  1. Frank says:

    The papers by you, Lindzen and Dessler that look at the correlation between surface temperature (anomalies) and TOA flux (anomalies) seem to depend on model that may be too simple. Only about 15% of surface LWR flux escapes directly to space. The remainder is trapped in the atmosphere and escapes to space efficiently only after it has reached the upper troposphere by radiation or convection. (Or been re-absorbed by the ground and emitted directly to space). How long does it take for the flux from the surface trapped in the lower troposphere to reach space? If this process takes longer than one month, the delay will interfere with finding a correlation between monthly averages of Ts and TOA flux.

    The average residence time of water vapor in the atmosphere is only nine days, so latent heat becomes sensible heat fast enough for monthly averaging.

    When I look at the UAH temperature data at discover.itsc.uah.edu/amsutemps/, I see that the highest surface temperatures occur in March, a few months after the perihelion. (The stratosphere, with its low heat capacity, appears to show almost no lag.) At 4.4 km (and 7.5 km), however, the warmest temperature occurs in July/August. Is it possible that it takes 3-4 months for a surface temperature anomaly to reach an altitude where it can easily escape into space? Your paper reports a better correlation with lag times of roughly this amount. Unfortunately, this process would likely smear the relationship between Ts and TOA flux over many months, greatly complicating the analysis. Changes in forcing clearly take months to change surface temperature and surface temperature change could take months to change TOA forcing.

    Respectfully, Frank

  2. Anthony Watts says:

    All for the need of some lubricant…sad.

    I wonder why they didn’t build in a reservoir for fresh lubricant? No Jiffy Lubes in space.

  3. Singer98406 says:

    So, what satellite will you be getting your temp data from going forward, and when?

  4. KevinK says:

    Dr. Spencer,

    With respect, WELL DONE. Making any satellite instrument function beyond its design life is a tribute to the science and engineering skills of many people.

    Too bad about the loss of continuum of the data from the first unit and the follow on unit.

    Cheers, Kevin.

  5. Jeff Id says:

    Damn, I have considered this the premier instrument for air temps since it was launched because of its station keeping.

  6. At http://www.iup.uni-bremen.de:8084/amsr/ you can read:
    The AMSR-E instrument has not produced data since Oct 4, 2011. Therefore, the sea ice maps cannot be updated. We are switching over to SSMIS data which might take a few days.

  7. Molon Labe says:

    Cui bono?

  8. Kate Pelly says:

    So, paid space folks, how do you plan to get it out of orbit so it doesn’t become another piece of floating space junk? It has a built-in deorbit mechanism, right?

  9. TerryMN says:

    Sorry to see it fail, but 150% of the designed lifespan is admirable.

  10. P.Solar says:

    It seems that satellites are like washing machines and everything else these days: it’s cheaper to buy a new one than to replace a bearing! It’s not the cost of the bearing but the call-out fee that kills it.

    Very unfortunate that there will be no data overlap. Satellite data is a valuable cross-check on the constant manipulation of surface data to pump up “global warming”.

  11. Nightvid Cole says:

    Just a nitpick: You mean angular momentum.

  12. Raleigh says:

    This is the wierdest thing I’ve ever seen. And I’m in pest control, you see a lot of wierd things. How did that sei whale get so far from the ocean???