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Twin GRAIL Probes To Map Lunar Gravity Field

Soulskill posted more than 2 years ago | from the magnets-how-do-they-work dept.

Moon 18

smitty777 writes "The two washing machine sized satellites from the GRAIL program (Gravity Recovery and Interior Laboratory) launched in September are set to enter lunar orbit this weekend. As can be seen from this nifty infographic, the probes will monitor the gravitational field from orbit via the precise distance measurements of microwaves passing between the two satellites. From the article: 'The twin spacecrafts are named Grail-A and Grail-B. Grail-A will enter the moon's orbit on New Year's Eve, Grail-B will follow on New Year's Day. "The purpose of the GRAIL mission is to obtain gravity data on the Moon. And with that data, the scientists are able to determine the structure of the lunar interior, from crust to core," said David Lehman of NASA's Jet Propulsion Laboratory.' This is similar to the earlier GRACE project, which not only helped map out the gravity field of the Earth, but also helped map drought conditions in the U.S."

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yuck (2, Funny)

MichaelKristopeit421 (2018882) | more than 2 years ago | (#38505370)

microwaved cheese is gross

Twin GRAILs (0)

Anonymous Coward | more than 2 years ago | (#38505392)

How Groovy!

Nice! now we can know drought conditions on moon! (1)

youn (1516637) | more than 2 years ago | (#38505428)

wait, i think we kind of already know that :p... just stick to gravity field I guess haha :p

Re:Nice! now we can know drought conditions on moo (2)

HornWumpus (783565) | more than 2 years ago | (#38505506)

You slay you.

Somebody ought to.

envisioned a washer and dryer in lunar orbit (0)

Anonymous Coward | more than 2 years ago | (#38505450)

and now I cannot stop giggling

Re:envisioned a washer and dryer in lunar orbit (1)

g0bshiTe (596213) | more than 2 years ago | (#38505684)

Bout time, half my wardrobe is machine wash in a vacuum and tumble dry.

Cool (3, Informative)

Metabolife (961249) | more than 2 years ago | (#38505566)

These probes work by communicating with one another and measuring the slight changes in speed they experience as they orbit together. This change in speed correlates to a slow-down due to different gravitational pulls, hence lunar densities.

Did anyone else... (0)

Anonymous Coward | more than 2 years ago | (#38505574)

...picture two flying space-washingmachines? :)

Re:Did anyone else... (1)

Ol Biscuitbarrel (1859702) | more than 2 years ago | (#38508296)

ARTHUR: Fine, um, I don't want to waste anymore of your time, but, uh
            I don't suppose you could, uh, tell us where we might find a, um,
            find a, uh, a, um, a uh--
    TIM: A what...?
    ARTHUR: A g--, a g--
    TIM: A GRAIL?!
    ARTHUR: Yes, I think so.
    KNIGHTS: Yes, that's it. Yes.
    TIM: Yes!
    KNIGHTS: Oh, thank you, splendid, fine.
            [boom pweeng boom boom]

September? (2, Interesting)

Anonymous Coward | more than 2 years ago | (#38505766)

Did these probes take a really bad detour or something? If I read it right, they were launched in September, and are just getting into orbit around the moon at the end of this month. The Apollo missions made the same trip in a couple days. Why the incredibly long delay?

Re:September? (3, Informative)

CrankyFool (680025) | more than 2 years ago | (#38505790)

When you have to fly oxygen, food, and water to feed humans, you have to make the trip happen much faster -- and therefore burn way moe fuel -- than when you can take your time because the only thing you're consuming is electricity (and you can recover some of it via solar).

Re:September? (4, Informative)

nojayuk (567177) | more than 2 years ago | (#38506128)

The SMART-1 probe launched by ESA took about 13 months to reach Lunar orbit, propelled by a small ion engine and solar panels. Even then it started from a geostationary transfer orbit as a Getaway Special piggybacked on the commercial launch of two communications satellites via an Ariane 5.

Re:September? (1)

Ol Biscuitbarrel (1859702) | more than 2 years ago | (#38508286)

I see that they're crashing both probes when their work is finished, too. NASA's really going skimpy on the delta V here.

Re:September? (5, Informative)

clj (153252) | more than 2 years ago | (#38506208)

Believe it or not, this long route (via the Earth-Sun L-1 (Lagrange-1) point is a lower energy trajectory (that is, it takes less energy to send the probes) than the more direct route followed by the Apollo missions. This allows for a smaller launcher (or conversely, a larger payload for the same sized launcher). See [] .

So many questions (0)

Anonymous Coward | more than 2 years ago | (#38505834)

I've always wondered; what will happen to the moon when it leaves orbit? Where will it go? What will it do? And how will its magnetic field help/hinder its journey?

Good (0)

Anonymous Coward | more than 2 years ago | (#38506096)

When we start building condos and Wal Marts on the Moon, we have to know where is the best place to 3D print them.

educational outreach as well (0)

Anonymous Coward | more than 2 years ago | (#38507986)

the space craft are carrying 4 cameras each that they are connecting to middle schoolers around the world:

GRAIL huh? (1)

rueger (210566) | more than 2 years ago | (#38553326)

Beware the Holy Hand Grenade! []
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