Why Do Lunar Satellites Eventually Crash Into The Moon?

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Spacecraft orbiting the Earth have remained in space since the 1950’s and may last for centuries more, but spacecraft orbiting close to the moon can crash within weeks. The reason for this is the lunar gravity field is lumpy, with geological features making the smooth orbits of space probes distort until they hit the surface.

The recent publication on the giant lunar impactor:

Moonquakes Paper

Footage and images taken from NASA’s Apollo, GRAIL and LRO programs.

  1. Wallace McDonut

    Nice vid. Thought you might show a cross section through the moon to describe why it’s shrinking.

  2. Andrew Craner

    Why do meteors always crash into craters?

  3. Jan Bruun Andersen

    Nice try Scott, but everyone with a passing interest in the moon knows that it is a self-aware spaceship named Dahak. Dahak was never constructed with a uniform mass distribution, which clearly is supported by the data from NASA.
    But a good try anyway.

  4. Headcrab

    Great! Now you got me panicking about if the Sun has a “lumpy” or “bumpy” gravity as well. Are there measurable variations?

  5. Arno nümuss

    Thanks, I just did look for a gravity map of the earth a few days ago. And I had no idea such a cool thing exists for the moon too.

  6. rosscoap

    God we can be smart sometimes! Great video 👍

  7. Bernd m

    Hey Scott. I just saw a line of lightspots in the nightsky, pretty shure that it was the 60 Starlink sattelites. Took some photos of it. Very amazing :)

  8. david johanson

    please keep that closing tune or sound clip. that bass in the background, love it!!!! one video you had didn’t have it, was bummed!!!!

  9. antigen4

    BET you could find some pretty spectacular meteoroids on the surface of the moon – what with there being practically no atmosphere to burn them up and all ….

  10. Bryan Allo

    I learned something new today. Thanks for sharing. Keep up the great work!

  11. Junk Mail

    5:35 Tipping my laptop 90 degrees Counter-Clockwise, and (stereoscopically) looking through either GRAIL-A or GRAIL-B,(make the two images look like three and inspecting the middle one) one can see irregularities between the “before and after”.
    There is much more disturbance on each site, going from the “ARROW” contact point and upward in the frame. Looks as though there was a greater TRAIL of thrown debris splashing further UP the image. MUCH ENJOYED. THANKS.

  12. Chris Crum

    Wouldn’t tidal forces from Earth keep the moon’s interior warm and thus prevent so-called shrinking?

  13. ronaldo alfaro

    Love your videos. Keep up the good work.

  14. flagship1701e

    Scott, You re really so good at teaching fantastic details. Thanks!

  15. Jeffrey Bue

    I would love to see a vid on the high speed rendezvous (3 hours) to the ISS versus the low speed one (3 days). It’s not obvious to me “why” the shortened version is used far less often the the standard/long version.

  16. MaximumROC

    Scott, You make complicated topics easier to understand. I marvel at your knowledge and learn something every time I watch one of your videos.

  17. Randy Smith

    I don’t know if it’s a factor but the Earth’s gravity must have much more effect on lunar satellites than the moon has on Earth’s satellites.

  18. Nathan Lovel

    you brought the old music back!!!!

  19. Gribbo9999

    Thanks Scott. Always guaranteed interesting videos.

  20. Jake Biddlecome

    I think Scott has been reading my mind. I was just thinking about the moons odd gravity yesterday and forgot to look it up. Thanks for the vid – and great timing!

  21. SternLX

    Man… I hate lumpy gravy-ty. 😜

  22. Mark Davis

    Thanks! Like others, I’ve learned a lot with this episode!

  23. Richard 1

    Are mascons possibilities for resource exploitation? A giant gold nugget or is is just variations in the cheese crust?

  24. Mykl S

    I love this! This is one of my favorite vids of you yet! I had no idea about this. And I thought I was learned and particularly nerdy in such things.

  25. Kinda Mike

    Lumpy Gravity new band name *_CALLED IT_*

  26. Yagotta Kidding

    I thought the near side of the Moon is heavier because it sunk in the gravity well of Earth when the Moon was still hot enough to be liquid. Now you say, there was a second impact that liquiefied part of the Moon.

  27. Philip Bannor

    These videos are great – informative and interesting! Thank you!

  28. Bad Informeiyon

    Since when do we exactly know that the Moon is geologically active?
    Anyone knows how to find scientific sources of this research on the web?

  29. jocrp6

    The moon still has a molten core and mars doesn’t?

  30. Eagles_Eye

    the moon quakes is actually just the shell breaking, soon that dragon like space monster from dr. who will hatch.

  31. sundhaug92

    Could they’ve used doppler-shift or phase-change to measure smaller details?

  32. Eric D'Aleo

    Is there Ageostrophic shear flow near the lunar surface?

  33. Inesophet

    Excellent video! Maybe do a video on the Ina formation at the northern part of Lacus Felicitatis ;) Thats one of the more cooler regions. Also check out the “interesting” things around Meskalyn, Rima Sosigenes and Hyginus. You gonna love it!

  34. Alan Roberts

    Thinking electron momentum and lunar deflection indices. Bit big for my ickle brain though. Maxwell xx

  35. Redthorn57

    This video was awesome, keep it up.

  36. michael obrien

    Your channel is high my favourites list.
    You were talking about moonquakes.
    If someone were to stand above the subduction zone during such an event, do you think (s)he could maintain his/her footing?

  37. Nonya Biness

    People can be so brilliant! Figuring orbits, etc…. It’s amazing stuff. I wish I had those math skills =)

  38. BFDT

    VERY GOOD PRESENTATION! <3 <3 <3 This Station!

  39. Damian Reloaded

    I saw a video a while back (yours?) stating that above 100km all orbits are stable?

  40. HorzaPanda

    I wonder how much supercomputer time it took to calculate that orbit? XD

  41. Moist-Mike

    Loved this vid! But Scott, it’s not pronounced “Moon” – It sounds more like “Mun”.

  42. Superbun

    The Lunar Reconnaissance Orbiter is in a “frozen” orbit…
    because the moon just won’t _let it go_

  43. Mike Thompsom

    Scott love your videos look forward to them. I’m curious something, giving Hydrazine high freezing point how is it kept in a liquid state in space ?

  44. efrandsen72

    7:49 I heard earth quakes :) Great vid! Thank you for explaining why the moon is hard to stay in orbit with.

  45. Mike Foster

    The earth also has a semi-plastic mantel and a liquid metal outer core surrounding a compressed metal core working to balance out earths gravity. The mass of the crust has the most variance in gravitational density but only represents a fraction of the over all mass of the earth. So, gravity tends to be homogeneous.

  46. Ee E

    Can you record for 1p so I can play you on my light?

  47. sed8me

    So for those of us that have taken the time to take the perfect Moon shot, only to blow the saturation for a bit of a mineral map . . . .
    That we’ve actually captured a *VERY* ruff element of the G distribution map..!?
    Now that’s dam exciting hey.

  48. William Swenson

    A moon as “lumpy” as my mother-in-law’s Thanksgiving gravy? I’ll never view that china boat with its unctuous fluid again without imagining an Apollo ascent stage floating in it.

  49. Flyte Industries

    You always have the most informative videos

  50. Eric Fielding

    Your comparison between the free-air gravity anomalies on the Earth and Moon is not entirely fair. The gravity anomalies measured by GRAIL are much larger because the GRAIL satellites flew much close to the surface (10-20 km if I remember right). I am not sure which Earth gravity you used, but it was probably from GRACE, which used the same two-satellite method for Earth, but it flew at around 500 km above the surface to avoid atmospheric drag. The gravity anomalies decay in amplitude rapidly with distance from the surface, so the GRACE anomalies are an order of magnitude smaller than the GRAIL anomalies.
    Gravity measurements on the Earth’s surface can have variations as large as what GRAIL measured, although they are typically a little smaller because the Earth’s crust is not as strong as the Moon’s.

  51. Blatantly Fake Name

    So much science it hurts, delivered by a handsome rogue! It doesn’t get much better than this.

  52. Aaron Simpson

    You are such a champion! These videos are insanely entertaining.

  53. Chris Peart

    Absolutely brilliant, Scott !!! Thank you 🙏🙏

  54. Dan Severns

    That just adds more to the awesomeness of the Apollo 12 / Surveyor story.

  55. Nik McIntosh

    Selenology is real mind-blowing stuff. Whatever-planetary-mass-body-we’re-talking-about-ology in general really. Is planetology the generic term for it?

  56. Avida Dollards

    Always learning awesome things 50 year after.
    Thanks Scott. Apollo program is so mind blowing

  57. Jim's videos

    Jeez if you want a plume off of the Moon all you need is a nuclear device, everyone will be able to see how awesome your results are.

  58. skuzlebut82

    This is one of my favorites that you have made Scott. Great job!

  59. epincion

    Brilliant! Something I had literally no knowledge about. Such a good explanation.

  60. 1_2_Die

    THAT’s the kind of informative video I’d like to watch 24/7/365/∞
    Tank you, Sir!

  61. Zoltán Pósfai

    “Ebb and Flow, the Holy Grail of the Lumpy Moon” – Sounds like a seventies sci fi novel :)

  62. Baschdi Ro

    I love how you changed from earthquakes to moonquakes :)

  63. Gunner R.A.

    Wow, so that’s why you have that Gravioli detector thingy in KSP!

  64. RWBHere

    It’s good to hear you correct yourself, after calling moonquakes ‘earthquakes’. Always wondered why lunar satellite orbits always seem to decay quite quickly. Thanks for the explanation, Scott. 🙂

  65. FXL

    That face when he says “fly safe” makes me want to reply “yes dad, I will…”

  66. 〉〉cerebral_malfunction

    You showed us the lumpiness in great detail but didn’t explain how this effects the orbital dynamics :\ Can we get a part 2?

  67. Hashtagrex

    such a strange thing to hear that the moon is possibly shrinking

  68. Tuning3434

    Last time I mooned somebody, they’ve also called me Lumpy…. I can relate with you, Mr. Moon!

  69. Pray for Mojo

    Wow amazing stuff, so much incredible information!!! Cheers!

  70. Mystic Virgo

    LOL so… Be funny if this was included in the next KSP update .. Lumpy Mun

  71. Wettpancakes

    This was so cool. I never thought about this before. Thanks Scott!

  72. Robert Price

    The space kraken is real.

  73. Curtis Youngberg

    Sounds like Apollo 12 essentially aimed at the wrong target so environmental effects would shift it to the correct target? I believe we normally call that Kentucky Windage?

  74. TwinShards

    7:48 What is a Earth-quake ? I never heard about that before.
    *Sarcasm, cuz moon-quake instead*

  75. Chris Sartain

    Very well explained, even I could follow! Thank you for another great video!!

  76. Dan Watt

    Scott this is quite possibly one of the best videos that exist on YouTube. Fantastic explanation, please try and feature more videos like this!

  77. VoteScientist

    Earth is lumpy too. Four lumps have to be factored into inertial nav systems.

  78. PalimpsestProd

    further confirmation that I’m subbed just to hear Scott say “Mun”.

  79. Milos de Wit

    Is a ksp breaking grounds video in the making?

  80. American Freedom-Fighter

    We should pack them full of fireworks, give us a bit of a show on the way out.

  81. John Kiljan

    This answers a question I’ve had for many years. Why isn’t there a cloud of small rocks orbiting the Moon in close orbit? After all, the Moon must be struck by meteorites frequently and some small percentage of the ejecta must enter into a low orbit. Moreover, a small percentage multiplied by many hits should still leave a lot of stuff circling over the surface at a low height. With no atmospheric drag, that would seem to leave them in orbit just about forever.
    This video answers that question.

  82. TheHueisOver™

    I would love to know more about moonquakes.
    i wanna see a moon volcano.

  83. A. I.

    So, does that mean we can use the gravity map to extrapolate places to focus on when looking at mining metals and other essentials for colonization of the moon?

  84. sophrapsune

    Thank goodness I managed to catch this before entering lunar orbit.

  85. zapfanzapfan

    I really like that rock sitting on top of the central peak of Tycho crater. Future tourist spot? :-)

  86. Gemmel

    Thanks I’d always wondered how they measured gravity, much appreciated.

  87. Pass The Butter Robot

    I see a lumpy moon a-rising
    I see trouble on the way (for satellites)

  88. John Smith

    i was under the impression that any orbit around a tidally locked body would eventually decay, lumps or not. This is why we don’t see moons of moons

  89. nagualdesign

    (4:30) Those maps of the Moon comparing elevation to gravitational attraction were surprisingly different.

  90. Free Saxon

    The tale of a lumpy moon and two spacecraft called ebb & flow, …….. as per usual informative stuff

  91. AwesomeSauce

    Hi Scot, Thank you, i just learned something i newer knew.

  92. Dustin Glenn

    Hey Scott, I know you’ve done videos on how rockets are ignited, but can you do a video about how rocket engines are started focusing more on the plumbing aspects? I’ve been especially interested in how you start something like an expander cycle engine.

  93. Rene Rye Larsen

    The Mün…

  94. C 3

    Grüße aus Deutschland :)
    Ty for teaching me how to dock in Orbit :P

  95. Liam Dennehy

    OK, but why do perturbations in the gravity field cause decay? Does the orbit become more eccentric?

  96. Upcycle Electronics

    Lumpty Dumpty as seen by all.
    Orbit Lumpty and you’ll fall.
    Most of the forces, full of mere men,
    Can’t orbit lumpty and get back again.

  97. Andreas Aristokrates

    The 6:16 orbit is pure beauty and deserves more attention and explaination.

  98. Max Mai

    You taught me a lot of things and I want to thank you for that

  99. Mightylink

    Things Kerbal Space Program doesn’t teach you…

  100. Daniel Bamberger

    Congratulations on asteroid (33434) 1999 FU having been named after you today! It is nice to see you, and Youtube, being honored this way. Quote:
    “Scott Manley (b. 1972) is a popular science communicator, best known for his videos on youtube combining science and games. Formerly an astrophysicist, he studied asteroid collisions at Armagh Observatory and created visualizations of the main belt and near earth asteroids.”

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