[HN Gopher] First up-close images of Mars's little-known moon De...
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First up-close images of Mars's little-known moon Deimos
Author : pseudolus
Score : 166 points
Date : 2023-04-25 10:39 UTC (2 days ago)
(HTM) web link (www.nature.com)
(TXT) w3m dump (www.nature.com)
| unwind wrote:
| Wow it's so small!! Only 12.4 km wide, that's miniscule! Earth's
| moon is like 3,400 km. No wonder they call it a "moonlet".
| mbreese wrote:
| I figured it was called a moonlet because it didn't have enough
| innate gravity to form a sphere shape. The pictures from the
| article have it looking quite bumpy.
| JKCalhoun wrote:
| Somewhere I read (was it Clarke?, Asimov? ... who knows) that you
| could pitch a baseball on the surface of Deimos, wait some number
| of hours (minutes?) and it would have orbited and returned from
| the opposite direction, you could then hit the ball with a bat
| and some time later catch it on the re-orbit and declare yourself
| out.
| Symmetry wrote:
| Escape velocity is just around 5 m/2 so don't pitch it too fast
| or it won't come back! Even a Little League pitcher should be
| able to throw a ball at 20 m/s or so.
| AnimalMuppet wrote:
| Pretty sure I can still do 100 m in less than 20 seconds,
| so...
|
| (Except, as others have said, I wouldn't have the traction to
| accelerate.)
| euroderf wrote:
| It should be possible to jump up off the surface at this
| speed too eh
| jandrese wrote:
| Probably difficult to do it as a high jump, but a person on
| a bike hitting a small ramp could do it no problem,
| assuming you could even find enough traction to get going
| fast enough in such light gravity.
| dsfyu404ed wrote:
| Skateboard and fire extinguisher.
| The_Colonel wrote:
| No need for skateboard in that gravity.
| dmoy wrote:
| I think it was Carl Sagan and Phobos. Not Deimos.
| sidewndr46 wrote:
| This is interesting. From what I understand Russia has launched
| multiple probes to the Martian moons and they all have failed.
| Amazingly, they still are planning at some point in the near
| future to launch the same Soviet-era designed probe again.
| rebolek wrote:
| And by near future they mean when we'll have nuclear fusion,
| which will be in near future too. I've been reading about their
| plans for 30+ years.
| euroderf wrote:
| Mars was eating US probes too. If you go thru archives you'll
| find cartoons of Mars eating everything thrown at it.
| pdpi wrote:
| It's sort of amusing to see Deimos described as "little-known". I
| grew up playing Doom, so I learned about Mars's moons Phobos and
| Deimos _way_ earlier than I did any of the other, better known
| moons in the solar system.
| EamonnMR wrote:
| In Marathon it was converted into the titular generation ship
| and launched towards Tau Ceti. But I suppose you could call
| Marathon little known too...
| temp0826 wrote:
| This was my first thought too as I grew up with the game.
|
| On the subject, for a little blast from the past...the
| Marathon's Story website is still around-
|
| https://marathon.bungie.org/story/
|
| 28 years old, a little noteworthy!
| ammanley wrote:
| You got some strangely heated responses to this, but I just
| wanted to say I share your boat. Its nice to see real pics as
| an adult now of it all. Also, my trip to Phobos and Deimos was,
| you could say, _hellish_. 11 /10, would rip and tear again.
| dllthomas wrote:
| It's a nice boat.
| kitsunesoba wrote:
| I think the first I heard of it was in another game, Ambrosia
| Software's top-down scroller _Deimos Rising_ , which came
| bundled with my Pixar lamp iMac back in the early 2000s.
| EamonnMR wrote:
| The soundtrack to that game really stuck with me, as it was
| installed on the eMacs in our classroom so we played it
| during indoor recess. Since the addons page is long gone, I
| threw the soundtrack up on the internet archive.[1] Ben
| Spees, who did the Soundtrack went on to found the math rock
| band Mercury Tree.[2]
|
| I mostly remember Ambrosia for the Escape Velocity series
| though, especially Nova.
|
| 1: https://archive.org/details/deimos_rising_soundtrack
|
| 2: https://themercurytree.bandcamp.com/
| sjrd wrote:
| Ah ah, similar experience here as well, though through the
| board game Terraforming Mars.
| bigbillheck wrote:
| [flagged]
| hammyhavoc wrote:
| I'm a Zone of the Enders nerd, so know about it through that
| too.
| dylan604 wrote:
| So, you know the name of the moon and what planet it orbits.
|
| Do you think we have as much understanding of Deimos as our own
| moon? Do you think we have as much understanding of this
| particular moon that never really had any close up analysis
| performed on it as much as any of the better known moons in the
| solar system where we've actually sent probes to fly-by/orbit
| and observe?
|
| In other words, little-known is not referring to do people know
| the name or not
| OkayPhysicist wrote:
| "little-known" as an adjective, in American English, is used
| exclusively when talking about people's awareness of the
| existence of a thing. With the title's phrasing, it literally
| does refer to people knowing the name or not.
| Simran-B wrote:
| Wasn't The Expanse popular in the US, though? Deimos was
| destroyed by UN forces during the Earth-Mars conflict in
| the sci-fi series.
| endisneigh wrote:
| at only 12km wide, I wonder how it would feel walking along it.
| [deleted]
| godshatter wrote:
| It's escape velocity is about 5.5 m/s, you might be able to
| sprint fast enough to float away from it. I suspect walking on
| it would be an exercise in tedium as you took a step and waited
| while you floated back down to the surface.
| simonh wrote:
| Falling a distance of 1 metre would take 25 seconds, and for
| a step 10cm high it would take 8 seconds.
|
| If you exerted the same force to lift your body upwards as
| you'd need on earth to rise by 5cm, as in going on tip-toe,
| you'd jump about 1.5 metres. It would take you well over a
| minute to land again.
| AnimalMuppet wrote:
| I used to have this dream where I was not quite flying, but
| if I jumped horizontally and then picked my feet up, it
| took a _very_ long time to fall back down. That would be,
| for me, literally "living the dream".
| gs17 wrote:
| Doom would have been a much weirder game if they had use
| realistic surface gravities.
| miohtama wrote:
| That's why you cannot jump in Doom. You would float off the
| sky box.
| ansible wrote:
| > _I suspect walking on it would be an exercise in tedium as
| you took a step and waited while you floated back down to the
| surface._
|
| With a surface gravity of 0.003 m/s, even slight twitches by
| an astronaut would be enough to launch off the surface.
|
| The flip side of that is a sample-return mission (as with
| OSIRIS-REx) could work with a similar mechanism and
| manuvering. Though obviously more delta-V is required to get
| into and get out of Mars orbit.
| kzrdude wrote:
| Any mission visiting would be in danger of perturbing the
| moon's orbit by shooting off from it, to go home, maybe? I
| wonder how space agencies would think about that.
| ansible wrote:
| I don't think that's a concern. The DART mission was able
| to alter the orbit of Dimorphos, but that asteroid is
| only 160 meters in diameter, much smaller than Deimos at
| 12.4km (mean diameter, it is oblong).
|
| Mass wise, we're talking about Deimos at 1.5x10^15 kg, vs
| Dimorphos at 5x10^9 kg.
| dustfinger wrote:
| Both my kids can't stop laughing because they think Deimos looks
| like a person's bottom - LOL!
| [deleted]
| bookofjoe wrote:
| The first person to set foot on Deimos is alive right now (but
| most likely NOT reading this).
| anigbrowl wrote:
| Is there any reason to try to land on such a small body, whose
| gravity is probably negligible?
| geuis wrote:
| Has anyone found a high res version of this image of Deimos
| against Mars in the background?
| https://media.nature.com/lw767/magazine-assets/d41586-023-01...
|
| Checked the mission site but they haven't updated their images
| page in quite a while.
| mzs wrote:
| WEBP:
|
| https://thenewdaily.com.au/wp-content/uploads/2023/04/168237...
| JPG:
|
| https://cloudfront-us-east-1.images.arcpublishing.com/estada...
| hooverd wrote:
| Alright, time to hollow that bad boy out and send it to Tau Ceti.
| needle0 wrote:
| I can't be the only one who initially misread UAE as UAC.
| DeathArrow wrote:
| You've played DOOM?
| someweirdperson wrote:
| The headline is probably wrong. Most likely, Deimos is a
| well-known moon, only second to Luna. Maybe tied with Phobos.
| Symmetry wrote:
| I bet the Galilean Moons of Jupiter are known to more
| people but yeah, Mars's are relatively well known.
| 867-5309 wrote:
| on Windows .. as Administrator
| nailer wrote:
| A lot of people don't realise this but there's a new made by
| the Wolfenstein 3D people.
|
| It has up and down AND walls can be at different angles!
|
| You're a space marine and fight demons.
| rendall wrote:
| Exploring the moons of Mars is all fun and games until you invent
| teleportation and unleash demons from another dimension!
| marcodiego wrote:
| My favorite photo of Mars with one of its moons:
| https://web.archive.org/web/20150426080937/http://mentalland...
| idlewords wrote:
| A fun Deimos fact is that there exist stable prograde orbits
| around it, while there are no such orbits around its bigger
| brother Phobos. Because Phobos orbits closer to Mars, its
| gravitational sphere of influence is smaller than its physical
| size.
|
| A nice paper on the different ways of orbiting the Martian moons
| and their trade-offs:
|
| https://sci-hub.ru/https://doi.org/10.2514/6.2012-5067
| franky47 wrote:
| Does that also mean you can't land on Phobos (and stay on the
| "ground" untethered)?
| rovingnothing29 wrote:
| So Phobos is space Australia.
| idlewords wrote:
| You can land on Phobos just fine, and unlike on Deimos
| there's no danger of accidentally jumping off into space
| (Phobos escape velocity is about 41 km/h). All the 'sphere of
| influence' stuff means is that orbits are too perturbed by
| unevenness in the Martian gravitational field and can't stay
| stable.
|
| Deimos is much smaller, but because it's further from Mars
| there is a region right above the surface (below 700 meters
| or so) where you could have stable prograde orbits.
| kzrdude wrote:
| Since both have gravitational acceleration below one
| thousandth of a g, I guess that counts as microgravity?
| Visiting those would be very interesting as an experience
| of gravity. I wonder if it would even be properly perceived
| as gravity, you'd have trouble orienting yourself and
| standing "up".
| idlewords wrote:
| It's a good question. There's been very little data on
| partial gravity, but what there is shows that a
| pronounced physical sense of "down" and "up" doesn't kick
| in until about 1/5g [1]. That said, a horizon and big
| rock underfoot are powerful visual cues, and it's
| anyone's guess what it would feel like to walk on a small
| celestial body like that. There's one good way to find
| out!
|
| [1] https://www.sciencedirect.com/science/article/abs/pii
| /S03043...
| Pxtl wrote:
| One unfortunate downside of tech limitations in the show
| The Expanse is that there's no good way to do low-g. Part
| of the first season is set on belter dwarf planets where
| the gravity would've been under 5% G.
| skykooler wrote:
| Does that mean that on the Moon (1/6g) you would have
| trouble telling which way is "up" if you closed your
| eyes?
| bbarnett wrote:
| _and unlike on Deimos there 's no danger of accidentally
| jumping off into space (Phobos escape velocity is about 41
| km/h)_
|
| That, sir, sounds like a challenge! I accept!
| marmakoide wrote:
| So a big spring would be enough to send one out from
| Phobos, that's neat. You can literally boink people to
| space.
| matthewdgreen wrote:
| Another moon that stubbornly proves to be an actual moon, and not
| an ancient alien space station.
| doublerabbit wrote:
| You sure it's not an alien space station disguised as a moon?
| ChrisMarshallNY wrote:
| If you watched _Moonfall_ , you learned that our own moon is
| actually an alien spaceship, and that only socially-
| maladjusted people can fix it.
| zw123456 wrote:
| I thought it's a control room for a reality TV show that we
| all star in.
| Cyphase wrote:
| That's true, man.
| someweirdperson wrote:
| It's the egg of an alien creature [0].
|
| [0] https://en.m.wikipedia.org/wiki/Kill_the_Moon
| AlgorithmicTime wrote:
| [dead]
| the8472 wrote:
| Martian invasion fleet disguised as a moon.
| https://www.project-apollo.net/mos/mos215.html
| mikeInAlaska wrote:
| I remember sitting on my front deck with my telescope watching
| Mars for a couple hours. The local atmosphere settled and the
| planetary features and colors were amazing. After a while I kept
| noticing a speck appearing and disappearing off the edge of Mars.
| After an hour it had definitely moved substantially. I ran in and
| checked my observatory software and it was Deimos !! Imagine
| that, a 7.7 mile diameter object seen visually from 43 million
| miles away.
| Jun8 wrote:
| Deimos looks so small w.r.t. Mars! Would Martians be able to
| enjoy solar eclipses? Answer :
| https://astronomy.stackexchange.com/questions/34953/is-earth...
| PicassoCTs wrote:
| Was it Deimos or Phobos, which could be decelerated to crash into
| mars with todays tech?
| keybuk wrote:
| We don't use that moon anyway
| henriquez wrote:
| Phobos is already on a doomed orbit, at only 10,000km above the
| surface it is very low and slightly decaying all the time.
| Eventually Phobos will be ripped apart by tidal forces in Mars'
| atmosphere and (at least partially) crash into the planet.
| h2odragon wrote:
| "eventually" the sun will expand and make the rest of mars
| valuable beachfront property again.
|
| Time to start selling real estate there. Get in _before_ the
| ground floor, imagine the profits! All the cool pipples are
| doing it, you wouldn 't want to miss out.
| geuis wrote:
| Here's the scientific findings video from 2 days ago from the
| European Geosciences Union conference
| https://www.youtube.com/watch?v=FtpGR-D7aTo
| Symmetry wrote:
| Next step, set up the Cape Dread port!
|
| http://www.projectrho.com/public_html/rocket/appcapedread.ph...
|
| EDIT: To summarize a big page, Demimos is relatively close to Low
| Earth Orbit in delta-v terms so it makes a convenient place to
| top up fuel tanks with volatiles extracted from the carbonaceous
| before heading further outwards. Maybe.
| ben_w wrote:
| I was thinking more along the lines of a colony ship for sale,
| cheap...
|
| https://en.wikipedia.org/wiki/Marathon_(video_game)
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(page generated 2023-04-27 23:00 UTC)