Is Phobos doomed?

November 25, 2014 by Fraser Cain, Universe Today
Is Phobos doomed?
Phobos (above) and Diemos (bottom) closeup; Credit: NASA

"All these worlds are yours except Europa, attempt no landing there."

As much as I love Arthur C. Clarke and his books, I've got to disagree with his judgement on which moons we should be avoiding. Europa is awesome. It's probably got a vast liquid ocean underneath its icy surface. There might even be life swimming down there, ready to be discovered. Giant freaky Europa whales or some kind of alien sharknado. Oh man, I just had the BEST idea for a movie.

So yea, Europa's fine. The place we should really be avoiding is the Martian Moon Phobos. Why? What's wrong with Phobos? Have I become some kind of Phobo…phobe? Is there any good reason to avoid this place?

Well first, its name tells us all we need to know. Phobos is named for the Greek god of Horror, and I don't mean like the usual gods of horror as in Clive Barker, John Carpenter or Wes Craven, I mean that Phobos is the actual personification of Fear… possibly with a freaky lion's head. And… there's also the fact that Phobos is doomed.

Literally doomed. Living on borrowed time. Its days are numbered. It's been poisoned and there's no antidote. It's got metal shards in its heart and the battery on it's electro-magnet is starting to brown out. More specifically, in a few million years, the asteroid-like rock is going to get torn apart by the Martian gravity and then get smashed onto the planet.

What fate awaits Phobos, one of the moons of Mars?

It all comes down to tidal forces. Our Moon takes about 27 days to complete an orbit, and our planet takes around 24 hours to complete one rotation on its axis. Our Moon is pulling unevenly on the Earth and slowing its rotation down.

To compensate, the Moon is slowly drifting away from us. We did a whole episode about this which we'll link at the end of the episode. On Mars, Phobos only takes 8 hours to complete an orbit around the planet. While the planet takes almost 25 hours to complete one rotation on its axis. So Phobos travels three times around the planet for every Martian day. And this is a problem.

It's actually speeding up Mars' rotation. And in exchange, it's getting closer and closer to Mars with every orbit. The current deadpool gives the best odds on Phobos taking 30 to 50 million years to finally crash into the planet. The orbit will get lower and lower until it reaches a level known as the Roche Limit. This is the point where the tidal forces between the near and far sides of the moon are so different that it gets torn apart. Then Mars will have a bunch of teeny moons from the former Phobos.

And then good news! Those adorable moonlets will get further pulverized until Mars has a ring. But then bad news… that ring will crash onto the planet in a cascade of destruction to be described as "the least fun balloon drop of all time". So, you probably wouldn't want to live on Mars then either.

The streaked and stained surface of Phobos. Credit: NASA

Count yourself lucky. What were the chances that we would exist in the Solar System at a time that Phobos was a thing, and not a string of impacts on the surface of Mars.

Enjoy Phobos while you can, but remember that real estate there is temporary. Might I suggest somewhere in the alien sharknado infested waters of Europa instead?

Mars with rings of moon dust after the fall of one of its moons, Phobos. Credit: Hive Studios

What do you think. Did Arthur C Clarke have it wrong? Should we explore Europa?

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

Explore further: Image: Phobos occults

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16 comments

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ibspider2_2
2.5 / 5 (8) Nov 25, 2014
I think the writer of this article is a buffoon. Phobos is one of the most interesting satellites in the Solar System. There are many anomalies on it's surface that some believe may be artificial. Whether this is so or not, the time frame of its deorbit is in the many millions of years. To even suggest that we should stay away from it, or Mars is ludicrous. Have you been paid off by the government, or the Luddites? Either post legitimate scientifically relevant articles, or get out of the way and leave room for those who will.
mokanmikey
5 / 5 (4) Nov 25, 2014
In Arthur C Clarke's 2010, the message to leave Europa alone was because life was beginning on this moon and we were not to interfere with that development. Europa is one of the most interesting bodies in our solar system. Get your story straight before publishing.
nEc
3 / 5 (6) Nov 25, 2014
It's Deimos....not Diemos. Editor? Also, filling phys.org with senseless articles, just to have more content....c'mon, you can do better. At least explain to Mr. Cain, that Sci-Fi has nothing to do with Sci...at least in reality.
cjn
5 / 5 (6) Nov 25, 2014
If, in 10M years, we do not have the technology or the capacity to either deconstruct Phobos or modify its orbit, I fear that our species will have greater problems.
Dredd
5 / 5 (1) Nov 25, 2014
Phobos has strata which leads me to believe it is a chunk of a larger entity.
imido
Nov 25, 2014
This comment has been removed by a moderator.
revisbell
1 / 5 (1) Nov 25, 2014
The author needs to use Spellcheck
Shootist
5 / 5 (3) Nov 25, 2014
Also it's presumed, Deimos contains lotta iridium, platinum and another interesting metals. We should implement cold fusion ASAP, send the robots there and to mine this boulder before it will crash the Mars.


No. Type I or II carbonaceous chondrites
imido
Nov 25, 2014
This comment has been removed by a moderator.
alfie_null
5 / 5 (8) Nov 26, 2014
Also it's presumed, Deimos contains lotta iridium, platinum and another interesting metals. We should implement cold fusion ASAP, send the robots there and to mine this boulder before it will crash the Mars.

No! No! No!

It's presumed Deimos contains lots of dilithium crystal. We should implement warp drive technology ASAP, send in the United Federation's robots to mine it quickly (within the next few billion years, as unlike Phobos Deimos is in a distant orbit, not threatened with relatively imminent destruction).
jwozniak
5 / 5 (1) Nov 28, 2014
"We should implement cold fusion ASAP, send the robots there and to mine this boulder before it will crash the Mars."

Riiigght...because by that time, MTR will have completely destroyed all of Appalachia (and all of us who live there), so lets fin another, pristine place to stripmine. And make sure there are no worker safety provisions in place at the new location, either.

imido
Nov 28, 2014
This comment has been removed by a moderator.
sidewaiise
5 / 5 (1) Nov 28, 2014
It's a very clever approach he's taken. By centering the focus on Europa, though argument you end up thinking about the future of 3 planets.

The obvious one is Mars, with so many already thinking about Mars as a potential future earth-like second home to colonize. I believe he gave a timeframe of 1M-2M years for Phobos to reach this critical distance at which the tidal forces tear it up. That is a LONG TIME. In the scale of human life and consciousness at least. It's sufficient time to plan for this sort of event and to model how it will actually effect the planet to avoid any hazard.

I think we should definitely explore and Colonize Mars, explore Phobos and definitely get more probes and possibly humans to Europa if it's safe. The question is what was the reason Arthur C. Clarke made his statement? What data was he working off and do we have more data today?
Shootist
not rated yet Nov 29, 2014
Sod off, swampy.

Captain Stumpy
not rated yet Nov 30, 2014
Why not to read something about it first before arguing?
@ZEPHIR
https://www.edx.o...OJ8mrzIW
Spectroscopically it appears to be similar to the D-type asteroids,[11] and is apparently of composition similar to carbonaceous chondrite material
https://openlibrary.org/books/OL3692211M/Physics_and_chemistry_of_the_solar_system
https://en.wikipe...asteroid
also see
http://sci.esa.in...-phobos/
http://www.scienc...06004039
http://adsabs.har...pt..249M
http://www.scienc...01967673
http://onlinelibr...4.f01t04
http://www.scienc...9090089R
there is more evidence for shooty and his condrites than your post
so- "Why not to read something about it first before arguing?"
Bob Osaka
not rated yet Dec 01, 2014
As far as we know no life exists on either Phobos or Mars, there lies nothing there to be doomed. Collisions occur with great frequency throughout the cosmos. Only living things can suffer doom. Unless some odd gravitational interaction occurs flinging it our direction, we have nothing to fear from Phobos. Mars, as the god of war worshipped so fervently here on Earth is another matter, our propensity for squabbling and bickering over the most trivial matters may lead us to doom ourselves.

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