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posted by martyb on Wednesday November 01 2017, @10:25AM   Printer-friendly [Skip to comment(s)]
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


Original Submission

Related Stories

Discovery of a Massive, 198 Kilometer-Wide Crater on the Moon 19 comments

The Lunar and Planetary Science Conference announced on 2015-03-16 that a 198 km wide crater has been found on the moon using the GRAIL spacecraft that uses gravitational field mapping. This enabled the discovery of craters below the surface. It's been named the Earhart crater. Nice gravitational photos can be found in the links.

Enter the Moon Cave 38 comments

Following up on a report from 2011, comes confirmation that, instead of a base on the moon, a better idea might be a base inside the moon:

"Japan's space agency said it had discovered an enormous cave beneath the lunar surface that could be turned into an exploration base for astronauts."

"The chasm, 50km (31 miles) long and 100 metres wide, appears to be structurally sound and its rocks may contain ice or water deposits that could be turned into fuel, according to data sent back by the orbiter, nicknamed Kaguya after the moon princess in a Japanese fairytale."

According to a science news article by UPI (United Press International):

In a new study published this week in the journal Geophysical Research Letters, scientists confirmed the presence of a large lava tube among the Marius Hills, a series of lunar lava domes.

The open lava tube could serve like a giant bunker, providing shelter from the harsh conditions on the moon's surface. In their study, scientists argue lava tubes offer ideal protection from extreme temperature swings, radiation and meteorite impacts.

Lava tubes form when the outer edges of a lava flow harden into crust and the remaining lava drains away, leaving an empty cylinder.

"It's important to know where and how big lunar lava tubes are if we're ever going to construct a lunar base," Junichi Haruyama, a senior researcher at JAXA, Japan's space agency, said in a news release. "But knowing these things is also important for basic science. We might get new types of rock samples, heat flow data and lunar quake observation data."

GRACE-FO Spacecraft to Switch to Backup System in Microwave Instrument 4 comments

GRACE-FO Satellite Switching to Backup Instrument Processing Unit

The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission team plans to switch to a backup system in the Microwave Instrument (MWI) on one of the twin spacecraft this month. Following the switch-over, GRACE-FO is expected to quickly resume science data collection.

A month after launching this past May, GRACE-FO produced its first preliminary gravity field map. The mission has not acquired science data since mid-July due to an anomaly with a component of the Microwave Instrument on one of the GRACE-FO spacecraft. The mission team is completing its investigation into the cause of the anomaly.

The primary science objective of GRACE-FO -- like its predecessor GRACE, which operated from 2002 to 2017 -- is to track how water is redistributed on Earth, by producing highly accurate, monthly gravity field maps. Measurements of changes in Earth's gravity field provide measurements of mass change and enable unique insights into Earth's changing climate, Earth system processes like droughts and sea level changes, and the impacts of human activities on water resources.

Gravity Recovery and Climate Experiment.

Previously: Gravity Recovery and Climate Experiment Ends, "Follow-On" Launching Soon
SpaceX to Launch 5 Iridium Next and 2 GRACE Satellites Today: Tuesday May 22 @ 19:47:58 UTC


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  • (Score: 0) by Anonymous Coward on Wednesday November 01 2017, @01:21PM (4 children)

    by Anonymous Coward on Wednesday November 01 2017, @01:21PM (#590545)

    Let's see. The "Gravity Recovery [...] Experiment".

    So, did they manage to recover any of that gravity? Why is that gravity being wasted, anyway? And where does it go if not recovered?

    Seriously, guys: "GRACE" sounds very cool, and I realize that a catchy mission name is somewhat important nowadays, and you're all scientists and not liberal arts majors. But couldn't you at least have _tried_ to use those words in a generally-accepted fashion? You know, they already had a meaning before you started using them. And there's also existing rules for grouping words together, to give them additional meaning (hint: grammar, semantics).

    If those generally accepted meanings and rules preclude you from forming a cool acronym that fits your project, then that's _your_ problem! You _still_ can't just ignore grammar and semantics. (well, obviously you could, and you still can, but you shouldn't, IMNSHO)

    And don't even try explaning the (b?)acronym now, because that'd just demonstrate your previous failure on the "generally-accepted" part.

    *sigh* I started this post aiming for "Funny", but with every additional word I realized that it's totally not :-/
    Scientists (_especially_ scientists!) should be aware that you can't just redefine stuff the way you need it. Not even language. Yes, even though it does not have a mathematical notation.

    On a similar note, how is that gravity's climate? Did your experimenting with it cause it any damage?

    • (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.

    • (Score: 0) by Anonymous Coward on Wednesday November 01 2017, @09:25PM

      by Anonymous Coward on Wednesday November 01 2017, @09:25PM (#590773)

      They recover a gravity model from the spacecraft data. Recover is used as a synonym for extract.

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