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posted by martyb on Wednesday November 01 2017, @10:25AM   Printer-friendly
from the Amazing-Grace dept.

A NASA and German Aerospace Center mission using two spacecraft to map the strength of Earth's gravitational field has come to an end:

The Gravity Recovery and Climate Experiment (GRACE) mission has come to an end after more than 15 years in Earth orbit. The twin satellites chronicled the changes of the Earth's water, ice, and land since the spacecraft were launched from the Plesetsk Cosmodrome on March 17, 2002, on a mission that was originally only slated to last some five years. More than a decade after that, GRACE was still beaming data back to Earth when a technical issued forced mission planners to close out the program.

Similar in some aspects to other missions launched, GRACE made precise measurements via the two spacecraft – GRACE-1 and GRACE-2 – that comprised the mission. For GRACE's overall scientific objectives to be achieved the two satellites both had to be fully functional. However, this past September (2017), GRACE-2 encountered a battery issue that made it clear by mid-October that the battery would not allow scientists to operate its science instruments and telemetry transmitter. It was decided to decommission GRACE-2 and, in so doing, end GRACE's scientific mission.

[...] GRACE helped detail how our home world's changing seasons move water, ice, and even land (as a result of surface water mass changes) across the planet's surface, providing researchers with a better understanding of what drives the motion of these substances. Earth's climate, earthquakes, and our own activities all play their part in shaping the face of our world and GRACE provided insights into the dynamics of this change.

GRACE was able to detect changes in Earth's gravitational field that is related to our planet's mass which is, perhaps unsurprisingly, impacted by the redistribution of water across the globe. The spacecraft judged the distance between its two components using a microwave ranging system which, according to NASA, had the ability to judge that distance "...within a fraction of the diameter of a human hair over 137 miles (220 kilometers)."

The "Follow-On" mission is scheduled to launch within the next few months. GRACE-FO will have a laser ranging system with 20 times the sensitivity of GRACE.

Two similar missions: the ESA's Gravity Field and Steady-State Ocean Circulation Explorer (GOCE), and Gravity Recovery and Interior Laboratory (GRAIL) which mapped the Moon.

Related: Discovery of a Massive, 198 Kilometer-Wide Crater on the Moon
Enter the Moon Cave


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  • (Score: 1) by khallow on Wednesday November 01 2017, @01:52PM (2 children)

    by khallow (3766) Subscriber Badge on Wednesday November 01 2017, @01:52PM (#590554) Journal
    Given that they could have thrown in a word like "Research" and gotten away with it, I think it probably has to do with what they're measuring. For example [nasa.gov]:

    Data from the mission also will allow scientists to more accurately determine the extent to which sea level is impacted by a phenomenon called "post-glacial rebound." This is the name used to describe the slow rebounding of Earth's crust now that the weight of the ice from the last ice age is no longer present. Post-glacial rebound accounts for the vertical movement of land in many parts of the world. These shifts affect relative sea level at the coastline in a way that varies from place to place. Such movements can confound tide gauge records obtained from coastal sites and thus complicate efforts to track the overall change in global sea level. Data from GRACE will be combined with altimeter readings to get a better understanding of how much of the perceived change in sea level is attributable to the phenomena of post-glacial rebound and how much might be attributed to global climate change.

    In other words, a key measurement was of the rebound of Northern hemisphere landmass following the end of the last ice age. I suspect that is the "recovery" referred to in the name.

  • (Score: 0) by Anonymous Coward on Wednesday November 01 2017, @02:12PM (1 child)

    by Anonymous Coward on Wednesday November 01 2017, @02:12PM (#590559)

    That's just the point: "I suspect that is the 'recovery' referred to".

    You are well-informed about the mission objectives (thanks for looking it up, BTW) and you _still_ can only guess at what the name stands for.

    I concur with your thoughts, there's probably a good reason for that wording. But shouldn't two scientifically-literate people, after looking at a more detailed project description, be able to discern it by now?

    Right now, the only impression I'm getting is that they couldn't find an expression that would fit their mission and the cool acronym at the same time. Although they really, really tried. And then someone said: "Let's be real, 99.9% of the unwashed masses will go 'Ah!Science Gibberish!' instantly. Wheres real people will be using GRACE from the start. So yes, it's incorrect, but stop wasting project money!".

    That line of reasoning sounds much to business-y to me to feel comfortable when scientists start doing it. Because I know all too well how those businesses work on the inside, and what that reasoning leads to.

    And I really, really, really don't want "my" science done that way!!

    • (Score: 1) by khallow on Wednesday November 01 2017, @02:41PM

      by khallow (3766) Subscriber Badge on Wednesday November 01 2017, @02:41PM (#590565) Journal

      That line of reasoning sounds much to business-y to me to feel comfortable when scientists start doing it. Because I know all too well how those businesses work on the inside, and what that reasoning leads to.

      With respect to NASA, that ship sailed long ago.