Lunar rock and roll

By Phil Plait | February 1, 2011 7:00 am

The Lunar Reconnaissance Orbiter has been taking extreme close-ups of the Moon since September 2009, and since that time I’ve posted dozens of these images, including shots of the Apollo landing sites, images of Earth from the Moon, craters, lava tubes, and more. But among my favorite of all these are the ones showing action, something that’s happened that you can actually see. And the best of these, I think, are from boulders rolling around on the Moon’s surface. Like this one!

lro_gassendi_boulder

[Click to embiggen and get a somewhat wider view.]

That boulder you see there is about 30 meters across — 100 feet — so it’s pretty big, the size of a house. It’s sitting inside the 110-km-wide crater Gassendi, and rolled down from the crater’s central peak. The trail is obvious, as are several smaller ones around it.

Funny– it seems obvious in retrospect (as so many things do), but I wouldn’t have predicted boulders rolling down slopes on the Moon. In my mind, even now, it’s hard to shake the prejudice that the Moon is dead, dead, dead. But it still has some activity; for example, the changing gravity it feels from the Earth as it loops around us in its elliptical orbit causes the Moon to stretch and compress. This can create seismic activity — moonquakes! And that can cause rocks to tumble downslope.

See? Obvious.

There are lots of images from LRO of this, too. Here’s one with rolling rocks and trails in Tsiolkovsky crater, and one of my all-time favorites shows a boulder that rolled down a slope and into a small crater: a lunar hole in one!

Back to that big guy up top; Gassendi was a landing target for Apollo 17 for a while, but the uncertain terrain (lunain?) made the planners decide to go elsewhere. Too bad: boulders that roll down from higher locations make it easier to get rock samples from different areas, since the rock already did the work of coming to you!

But maybe, just maybe, we’re not quite done with the Moon yet. I hope to once again see people walking on its surface, and instead of seeing pictures like this from above, we’ll have shots of astronauts living and working there, taken by their own hands.

Image credit: ASA/GSFC/Arizona State University


Related posts:

- Ash hole on the Moon
- Exquisite rubble
- One giant leap
- Gettin’ high on the Moon


CATEGORIZED UNDER: Pretty pictures
MORE ABOUT: LRO

Comments (29)

Links to this Post

  1. Rocas Lunares que Ruedan. | Pablo Della Paolera | February 1, 2011
  1. Tail

    What was the impetus that started the bolder rolling? Was it sitting there and some force acted on it to start it moving? Precariously balanced, did daily heating and cooling eventually erode out enough material that it tumbled—is that a mechanism that occurs on the moon? Or was it flung through the air by some volcanic process, only to roll down from the rim after it landed?

  2. Pete Jackson

    Have you noticed the rather obvious (to me at least) face in the rock? Have your browser embiggen it (CNTL+ in Firefox) to help see it. I’ll tell you where it is if others have difficulty seeing it. I expect to see it soon in the National Enquirer!

    This obviously had once been part of a statue to some lunar dictator or emperor who got overthrown in one of the lunar insurrections.

  3. Dean

    Had to chuckle at this: “Too bad: boulders that roll down from higher locations make it easier to get rock samples from different areas, since the rock already did the work of coming to you! ”

    Except in this case, the work involved coming up out of Earth’s gravity well. :-)

  4. Brian

    I can’t make out a face on the rock that did the rolling, but the rock at the top looks like a pacifier.

  5. thetentman

    “30 meters across — 100 feet — so it’s pretty big, the size of a house” Phil how big is your house? I know mine’s not nearly 100 feet. In fact that’s bigger than my property.

  6. Brian Davis

    Yes, it would be nice to sample rocks that rolled down from somewhere. Conversely, anywhere with a steep enough slope to roll a boulder might make for a very… interesting… landing area for the LM.

  7. So, any way to estimate how long ago it rolled down the hill?

    And what are the chances of catching one “in the act”, as has been done a few times on Mars? (Of course, it wouldn’t have the billowing clouds of dust around it.) Or, at least, a “before” and “after” image taken some time (years?) apart.

    thetentman:

    Phil how big is your house? I know mine’s not nearly 100 feet. In fact that’s bigger than my property.

    Ditto. Around here, a “building lot” is 25×100 feet, though there are houses built on multiple lots.

  8. Zucchi

    Imagine standing (not in the way!) and seeing that happen on the Moon. The silence would be eerie — but I guess if you were standing nearby, you might feel vibrations through your feet, maybe even get a little sound.

    I notice a few small impact craters within the path of the boulder, showing that the impacts happened after the boulder’s tumble. I wonder how long ago that was.

  9. So what Phil is saying is that his house is large enough for some serious partyin’? On a serious note, LRO continues to be an awesome treasure trove of information.

    Now, lets put some people up there. :)

  10. Charlie Young

    So if that was the Apollo 17 landing site, would the risk of a boulder rolling on top of the lander have been a predicted risk?

  11. Following the boulder’s path uphill, just near the top of the image is an “eye” shaped rock, sitting on the path of the boulder. The uphill side of the boulder appears to have a chunk missing. I wonder if that “eye” broke off during the roll? It’s about the right size.

    Also, about 40-50 meters to the right of the boulder’s path is a smaller track, but I don’t see anything at the bottom. It appears to just end.

  12. @1. Tail: could have been a moonquake…..hey, it happens!

  13. Trebuchet

    I’m seeing a couple of other, smaller, trails as well. Quite a few of the small bright rocks seem to have them. I agree with Ken B that the “eye” rock looks as if it could be broken off the big one, perhaps from the somewhat fresher looking surface at the top.

    I wonder, however, if the rock might have slid in portions of the track instead of rolling. The trail looks pretty deep for a rolling object in parts, then there are shallower portions when it might have rolled. It’s hard to tell from the photo how round it might be.

  14. Anchor

    The first example of this kind of kinetic activity on the ‘dead’ surface of the Moon I ever saw was both startling and haunting, considering that a specific event can be so faithfully preserved in the lunar reglith for hundreds of millions of years. It was an image acquired by one of the Lunar Orbiters sent to the Moon in the 1960′s, which spotted a boulder near Vitello crater that had rolled down one slope and apparently part way up a rise, curving its track. I was an eleven-year-old kid when I saw that electrifying photo in a book by Arthur C. Clarke, “The Promise of Space”. That was the one shot that really hit home the realization that ALL the markings and features on the surfaces of planets everywhere, no matter how subtle or minute, came to be there because of some event, that the surfaces were telling terrifically fascinating and intricate stories of what happened in the ancient past and how that past links contiguously unbroken to the present, where we can see first hand how nature keeps adding new chapters to the story. That’s what fostered my passionate interest in geology, astronomy and all the sciences in general.

  15. Chief

    Looks like I can store several rocks on my 150×200 lot. Although it would take out the house.

    I am amazed by the detail you can see in this shot. I’m curious why the Descent Stages of 11 to 17 have not had this level of detail.

    Does anyone know if the astronauts have experienced any quakes on their travels on the moon.

  16. Joseph G

    @15 Anchor: Cool! I’d like to see more stories like that; moments where an observation or fact caused that person to become fascinated by science (or a particular branch of science).
    I know Phil had a Twitter contest in sort of the same vein, about “Why I am a Skeptic,” but Twitter doesn’t really give you enough room to post the sort of thing that you did there.

  17. Joseph G

    @16 Chief: I don’t believe any astronauts have actually experienced noticeable moonquakes, but quite a few were recorded by seismometers left on the moon.
    These links may interest you:
    http://www.earthmagazine.org/earth/article/24d-7d9-8-13
    http://science.nasa.gov/science-news/science-at-nasa/2006/15mar_moonquakes/

  18. vince charles

    Cue Messier Tidy Upper, with a political agenda… or rather, an agenda for other people’s politics.

    And some Wikipedia entries I’m already bored of.

  19. Joseph G

    @19 vince: Thank you for that highly relevant and information-packed comment! Extra points for snarking about someone who hasn’t even posted yet.
    I honestly don’t know what we ever would have done without you. Really, I don’t. Thank you, citizen!

  20. Peter

    I, as well, would love to know if it’s possible to give a approximate minimum and maximum time that the rock could have rolled. And might it have slid?

  21. Douglas Troy

    Space Aliens must have pushed it there, because what Phil is saying makes wayyyyyyyyyyyyyyyyyyy to much sense to be true and we all know Phil is a scruffy-looking nerf-herder and can’t be trusted.

  22. Pete Jackson

    Nobody found the face? Well, it’s on the extreme right side of the rock, and mostly in profile.

  23. Nigel Depledge

    @ Tail (1) and J Major (13) -

    The BA said:

    . . . the changing gravity [the moon] feels from the Earth as it loops around us in its elliptical orbit causes the Moon to stretch and compress. This can create seismic activity — moonquakes! And that can cause rocks to tumble downslope.

    The answer to the question is in the article.

  24. Nigel Depledge

    @ 19 & 20 -

    Heehee!

    Both comments made me LOL.

  25. Zeke Dawdy

    “hard to shake the prejudice that the Moon is dead, dead, dead”. Well, I appreciate your honesty.

    I did a comparison survey of Lunar Orbiter 4, frames 4188 med, 4182med and 4190med with 1993 Clementine imagery. New crater 2.1 miles across at IAU 88W, 49.5N, (271.6 longitude, 49.5 latitude) the interior of Galvani B.

    I sense your eye rolls. Tried ALPO through Brian Cudnick, but I sense the eye witness account of the impact sets off major “prejudice” alarm bells, (as it rightfully should).

    Facebook me if you want my research. It provides links to the image data for independent analysis and verification. Doesn’t take much to find it all yourself with the info I have already provided here.

  26. Messier Tidy Upper

    @19. vince charles spewed out :

    Cue Messier Tidy Upper, with a political agenda… or rather, an agenda for other people’s politics.

    Yeah, because I’m the only person who ever says anything about politics here. :roll:

    See, for instance, the totally irrelevant and mean-spirited anti-Republican partisan comments by #85.Atheist Warrior & #86 Lugosi on the ‘Motherlode of potential planets found: more than 1200 alien worlds!’ thread.

    And some Wikipedia entries I’m already bored of.

    Well don’t click on or read them then! :-P

    Don’t like what I have to say? Find reading something from another perspective hurts your mind, then skim past and don’t read my comments, that’s your loss not mine.

    Oh but I forget this blog is supposed to be all purely for you & only what you, vince charles, like & desire … :roll:

    Oh wait, it’s NOT. :-(

    If the BA asks me nicely to change how I post here then I’ll listen to him because, y’know it is *his* blog. OTOH, you pushing in rudely and insulting me, not-so-much. And thinking of the BA’s wishes – you, vince charles, are breaking the BA’s “don’t be a jerk” policy.

    @20. Joseph G : Thanks for your support there – much appreciated. :-)

  27. Messier Tidy Upper

    Because it needs saying and since (#19.) vince charles has asked so nicley
    for it :-P :

    maybe, just maybe, we’re not quite done with the Moon yet. I hope to once again see people walking on its surface, and instead of seeing pictures like this from above, we’ll have shots of astronauts living and working there, taken by their own hands.

    We were going to go back, remember, the President you seem to revile had a plan to get us back there :

    http://www.youtube.com/watch?v=aq_4Mm-1-C0&feature=fvw

    Which could have been magnificent and accomplished some superluminous things.

    It was finally starting to get off paper and into the sky with a succcessful test flight :

    http://www.youtube.com/watch?v=H0ZHzAvFuYc

    When the President you choose to adore decides to cancel it, brushing off the idea of returning to the moon because “we been there before”.

    Thus we don’t need to explore further and settle the moon just as theEuropeans didn’t need to return to the Amercia’s once Columbus discovered the

  28. Messier Tidy Upper

    D’oh! That’s :

    Thus we don’t need to explore further and settle the moon just as the Europeans didn’t need to return to the America’s once Columbus discovered the new continent.

    Just as Middle-ages China didn’t need to follow up its medieval explorations by Zheng He :

    http://en.wikipedia.org/wiki/Zheng_He

    in the fifteenth century and benefitted from burning its boats and forgetting about going anywhere. Because that worked out so well for them – NOT. :roll:

    In fact, it worked out so badly, the Chinese are still of blaming our Western civilisation that *did* summon up the gumption to go boldly forth to explore and settle the world as evil “colonialists” today so many centuries on. (While simultaneously the Communist Chinese, of course, ignore their own acts of genocidal “colonialism” in Tibet and Xinjiang, their own imperialist menacing of Taiwan and elsewhere.)

    Civilisations either choose to advance and keep exploring further and achieving ambitious “hard” things (as JFK put it) or they quit, opting for the “easy” choice of doing less and consequently stagnate and eventually fall. Obama would have us choose the latter over the former. :-(

    Now Obama claims, of course, that his space policy isn’t doing that. I disagree as do many others incl. Neil Armstrong, NASA’s first space flight director Chris Kraft*,Apollo 13 astronaut Jim Lovell and many others.

    * See : http://www.yourhoustonnews.com/bay_area/news/article_db82e164-baff-5a24-80ac-c26b76e23aa6.html for example.

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