Talk:GRAIL

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Lunar orbit[edit]

Presumably they will go into a polar orbit to cover the surface every 14 days. What is the planned orbital period ? 1.5 to 2hrs ? Moon Circumference (equatorial) 10,921 km suggests the ground track (at equator) of each orbit will shift by how many km (~25-30km?) ? - Rod57 (talk) 10:42, 2 September 2011 (UTC)[reply]

Just a comment: a lunar orbit with period = 1.5hrs has a radius considerably less than that of the mean lunar surface. The satellite would be orbiting deep underground. — Preceding unsigned comment added by 24.223.130.60 (talk) 21:45, 13 January 2013 (UTC)[reply]
Rod57, https://www.nasa.gov/mission_pages/grail/news/grail20120327.html says the orbital period was 114 minutes.
https://www.jpl.nasa.gov/news/nasas-grail-a-spacecraft-24-hours-away-from-moon says the period was "just under two hours" and "the two GRAILs will be in a near-polar, near-circular orbit with an altitude of about 34 miles (55 kilometers)." Also from the second link is "The collection of gravity data over one complete rotation (27.3 days) is referred to as a Mapping Cycle." --Marc Kupper|talk 06:44, 25 August 2023 (UTC)[reply]
Thanks Marc Kupper. I've used the first link to make some small updates to the article. - Rod57 (talk) 13:19, 27 August 2023 (UTC)[reply]

launch attempt table[edit]

I don't see any need for the launch attempt table to be sortable (on the columns). Bubba73 You talkin' to me? 03:54, 11 September 2011 (UTC)[reply]

No propulsion system information[edit]

I was curious what was used to make these satellites reach the moon (given it has taken them a couple of months since launch), expecting some information about that (and frankly, expecting they were using ion drives or such). That information (if made available in a form that is acceptable to use on Wikipedia) would be valuable for the article. (If nobody objects and I find time, I can try to dig on NASA's web site...) --IllvilJa (talk) 09:17, 30 December 2011 (UTC)[reply]

Each spacecraft has a propulsion subsystem and engine. I'll add a section on it.--RadioFan (talk) 14:49, 30 December 2011 (UTC)[reply]

Ranging accuracy, and width of human hair[edit]

0.1 micron is not half the width of a human hair. The washington post articlehttp://www.washingtonpost.com/blogs/innovations/post/nasa-to-crash-probes-into-the-moon/2012/12/17/2f2d2b80-4871-11e2-b6f0-e851e741d196_blog.html got it wrong, as did their source, the NASA article http://www.nasa.gov/mission_pages/grail/news/grail20120327.html .

From Hair "The diameter of human hair varies from 17 to 180 micrometers..."

I can't easily find anything of this order of magnitude, perhaps a virus, but they vary a lot. I've deleted the reference to a human hair for now. Perhaps someone else can add a physical-world analogue to the article.

Thomasonline (talk) 22:27, 19 March 2013 (UTC)[reply]


Now digging to find the actual accuracy, the best reference is this: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120009915_2012010042.pdf (you might need google cache) shows that the ultimate performance of the ranging system seems to be just under 1 micron, depending on the averaging time. It is a stretch to say it could achieve 0.1 micron.

So the original article is wrong in both ways.

I've updated the article to reference the NASA PDF, and called the range about 1 micron.

Thomasonline (talk) 22:48, 19 March 2013 (UTC)[reply]

New section is needed[edit]

This article needs "results" section. --Artman40 (talk) 14:36, 21 October 2014 (UTC)[reply]

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Requested move 19 February 2018[edit]

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: Moved. (non-admin closure) –Ammarpad (talk) 11:01, 26 February 2018 (UTC)[reply]

Gravity Recovery and Interior Laboratory → GRAIL – In line with the naming conventions for spacecraft on Wikipedia. There is no disambiguation for the all-caps "GRAIL" name. The existing link is, in fact, a redirect to this article. Other examples of this naming convention include LCROSS, MESSENGER, STEREO, SMART-1, and NEAR Shoemaker. WP:COMMONNAME is also applicable in this circumstance, as "GRAIL" is referenced as the mission's name more than its full title. NASA never uses its full title outside a lead sentence, opting to use the acronym to refer to the spacecraft frequently in press releases (Examples 1, 2, 3). The official NASA Solar System Exploration entry for the mission is "GRAIL" The spacecraft's manufacturer Lockheed Martin uses the "GRAIL" name liberally, and news coverage almost exclusively uses the "GRAIL" name in both capitalised and non-capitalised forms (Examples 1, 2) – PhilipTerryGraham (talk · contribs · count) 21:34, 19 February 2018 (UTC)[reply]

The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.
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