Comments on: Phobos Might Only Have 10 Million Years to Live

By: Ricky Diaz

Ricky Diaz — Thu, 22 May 2008 10:06:26 +0000

We have ways we can send Phobos on a collision course with Mars in our lifetime, but it would be sad to lose a moon in the Solar System and Mars is a rocky planet, not a gas planet, so moons are more rare. Mars has only 2 captured by Mars' gravity. Mars is considered a moon destroyer. Many craters have been found on Mars that are basically oval shaped, meaning the impactor came at a very low angle, very likely moons. Phobos might form a crater over 850 miles long. The low angle might be enough for the collision to knock Mars off it's axis, but maybe not change it's rotation speed much. For example, Venus didn't used to spin backwards. And the rotation period used to be 224 days, because Venus used to be tidally locked to the Sun, having a rotation period equal to the orbital period. Then sometime, Venus was struck by a massive asteroid, maybe 375 miles across and at a low angle, which caused the collision to knock Venus upside down (relative to the plane of the Solar System.) But the rotation speed didn't change. The reason why it now spins once every 243 days, which is longer than 1 orbital period, is because it's gradually becoming tidally locked to the Sun again. It spins backwards, so for it to become tidally locked to the Sun again, Venus' rotation speed must slow down to zero and then begin rotating the right way again and again gradually- become tidally locked to the Sun again. So Venus' rotation period will eventually become much much longer. A period of more than 100 years. The questions are: By the time it reaches that speed, how fast will the rotation speed be changing? Will it make a rotation in a complete 1,000 years? 10,000 years?

I understand I explained more about Venus than Mars. I like teaching that fact about Venus' past and future.

By: marcellus

marcellus — Thu, 15 May 2008 03:52:57 +0000

Seven million years is a LONG time in human terms. The future Martians won't need to worry about Phobos while they get colonization up and running. Watching Phobos from the surface of Mars would be a nice distraction from the grind of terraforming that planet to human sustainability.

By: Cosselbray

Cosselbray — Wed, 14 May 2008 22:37:59 +0000

Why not try to bring Phobos down early to help warm up Mars? A benefit now rather than a problem in the future.

By: tacitus

tacitus — Wed, 14 May 2008 14:06:04 +0000

If we're still living on Mars in 7 million year's time, I suspect we'll have had the capability to stabilize Phobos's orbit for a long, long time before that.

By: Dave

Dave — Wed, 14 May 2008 13:59:35 +0000

I've always wondered if the tidal forces from the Moon played a role in plate tectonics here on Earth. Any thoughts?

By: alphonso richardson

alphonso richardson — Wed, 14 May 2008 13:58:19 +0000

Wow. too bad we won't be around to see it: I'd love to watch that

By: Steve

Steve — Wed, 14 May 2008 13:27:34 +0000

I always heard that tidal forces of the Earth's oceans are the cause for the moon receding. Is this not the case? I've never heard the "slingshot" theory from when the moon formed.

By: pantzov

pantzov — Wed, 14 May 2008 07:12:37 +0000

can someone tell me what effect this event, whenever it happens, will have on the orbit of mars and/or the planet's rotation?
a little?
a lot?

By: Craig

Craig — Wed, 14 May 2008 07:02:36 +0000

Except that we CAN'T breathe easily about the Moon having an outward-spiraling orbit. When the Moon eventually tears itself out of the clutches of Earth's gravity, all Hell will break loose on Earth.

There are significant negative impacts the loss of our natural satellite will have on this planet.

By: D-wreck

D-wreck — Wed, 14 May 2008 06:05:42 +0000

That's going to be too bad for any Mars inhabitants, assuming we colonize the red planet.

By: Astrofiend (Syd, Aust)

Astrofiend (Syd, Aust) — Wed, 14 May 2008 01:57:05 +0000

That should make for a great show!

I wonder – will that make for a crater ring encircling Mars as these ring pieces eventually get sapped of their angular momentum and de-orbit? That would be great!