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where is Fram Crater

Hi, I have been trying to find the coordinates of Fram Crater and it seems I cannot find it at all on the IAU Gazetteer of Planetary Nomenclature. Is it not an official crater? I found many references on the NASA website but not coordinates. Thanks --Golan's mom (talk) 06:14, 10 October 2018 (UTC)

Our article is at Fram_(crater). As you say, it's definitely not on the IAU list, so presumably unofficial. Henry^Flower 14:22, 10 October 2018 (UTC)

1.9°S 5.5°W - according to our article List of craters on Mars. It may not be listed as it is very small (8 metres in diameter) so is only known from images taken by the Opportunity rover - it may not be visible on images taken from orbiting satellites. Wymspen (talk) 14:27, 10 October 2018 (UTC)

Fram Crater is not presently in the database at NASA JPL's MarsTrek. The only reputable source cited by our article is this JPL PhotoJournal website, where "Fram Crater" is described in "scare quotes." However, I went looking for other reliable sources and found the Science Magazine Special Issue (Vol. 306, Issue 5702, December 2004): Opportunity at Meridiani Planum. This issue mentions Fram Crater in multiple papers:

• Mineralogy at Meridiani Planum from the Mini-TES Experiment on the Opportunity Rover (Science, 2004)
• Soils of Eagle Crater and Meridiani Planum at the Opportunity Rover Landing Site (Science, 2004)

...and the penultimate paper for you, our reader-with-interest-in-interplanetary-localization:

• Localization and Physical Property Experiments Conducted by Opportunity at Meridiani Planum (Science, 2004)

There is a lot of very difficult theory and practice that pertain to describing a location on another planet - especially when we start talking about putting landers and rovers on said planet with the intention of driving to features of interest - so that last paper is the one you should read first.

Additionally, the 2006 issue of IEEE Robotics included a paper from the JPL navigation experts: Jeff Biesedecki et al.: Mars exploration rover surface operations: driving opportunity at Meridiani Planum (IEEE Robotics & Automation, 2006), in which the authors take credit for informally naming the Fram Crater. They also present lots of fun technical details about why nobody knows where this crater really is:

"With considerable slip and time constraints preventing use of visodom, we knew the rover's internal position estimate would not be very accurate. Not making use of the internal position estimate precluded the use of Go_To_Waypoint and Turn_To commands, conditional sequencing based on estimated distance to a Cartesian location, and even remote sensing commands designed to image specific X, Y, Z coordinates. Instead, our mobility sequences were almost all geared to using combinations of Turn_Absolute and Arc commands based on predictions of what our slip would likely be."

..."Drives along the rim were all done with Arc and Turn_Absolute commands. We were driving on generally rocky berm, on a slope that was away from the crater interior (so slip would take us away from the rim itself, which we liked). The drives were kept short enough that we had a clear view of our drive path and could verify it was clear of obstacles and ejecta. We avoided doing sharp “dog legs” because we were driving far enough that stereo range data was not precise, and we did not trust the precision of our localization in the orbital maps. So most days were straight drive segments, approximately 40 m/sol."

I have added links to these references to our article.

So - the location of the landing site is known to better than 10 meters accuracy; the location of certain other crater features visible from orbit can be known with excellent precision - but the positions for many of the features that Mars Exploration Rover Opportunity actually visited and photographed are not accurately known. We can safely say that Fram Crater is a few days drive - perhaps a couple hundred meters - from the nearest big rock, informally called "Bounce Rock" - but otherwise at unknown distance and bearing, on the featureless terrain of the plains of the Meridiani.

Nimur (talk) 17:31, 10 October 2018 (UTC)

Other sources which discuss the crater, although probably don't help with the localisation, that I came across earlier are Crater gradation in Gusev crater and Meridiani Planum, Mars and Opportunity rover localization and topographic mapping at the landing site of Meridiani Planum, Mars. BTW this source [1] which I added to the article discusses how these unofficial names for the crater came about. The unofficial names don't comply with the IAU naming rules, so I don't think they were intended to be possible official names. Nil Einne (talk) 18:25, 10 October 2018 (UTC)

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