Kiri writes –
Ok, then–thanks very much! Now… *clears throat*
1. Do you know of any unfrozen water on Mars?
2. Is there any evidence of life on Mars’s moons?
3. What is/are Phobos and Deimos’s general profiles? (i.e.
Atmosphere, temperature, ect.)
4. What might Martians be like?
6. What are some famous theories on Martian life?
Thank you very much for your time!
Kiri, good questions. I will take them in order.
Unfrozen Water on Mars
First I will refer you to a blog post I try to update every time there is a discovery of water on Mars. Pretty much all of these discoveries are of ice – though some are of ice that sublimes (evaporates) into a gas.
You know how when you have an ice cube, if you let it sit out it melts into a puddle of water, and if you let that puddle of water sit out eventually it evaporates and you’re left with nothing? Well, on Mars you get to skip the “puddle of water” part, and ice evaporates directly, without melting first. This is called subliming. Intriguingly this happens in Seattle fairly often too: when we get enough snow to cover the ground the air is usually also pretty dry. We usually do not have rain for a few days. You can watch how the snow disappears, but the ground around the snow stays dry.
Here is a picture of what it looks like:
Notice how the ground around the snow is not wet, but you can tell that there is now less snow than there was when the snow must have fallen? On Mars this is what almost always happens, because it is so cold on Mars.
Now, here’s the other piece.
This is evidence of liquid water. As you know from seeing rivers, streams, and from looking at the Grand Canyon, water can shape the land. It can cut valleys, pick up loose dirt, and even reshape rocks. In the pictures linked to in this press release you can see a new gully.
There are other ways this gully could have formed, but it does look quite a lot like a gully formed by flowing water. Although NASA didn’t catch a picture of the water itself, this suggests that there was liquid water flowing on Mars between 1999 and 2005.
Life on Mars’s Moons
Nope. Mars’s moons are tiny rocks in space, there is no indication that they have the things we think are necessary to support life: liquid water, a temperature at which water can be liquid, and preferably an atmosphere of some type.
Phobos and Deimos’s General Profiles
Phobos has an average diameter of 22.2 km – that’s like the distance from the Pacific Science Center to SeaTac Airport. For comparison, our Moon has a diameter of 3476 km or the distance from Pacific Science Center to Chicago. Deimos is a little more than half the size of Phobos: 12.6 km or a little less than the distance from Pacific Science Center to the Museum of Flight.
It is probably useful to think of Phobos and Deimos as small asteroids rather than as moons – they do in fact orbit Mars, but they’re just tiny rocks. They are thought to be partially ice inside, and Phobos has a thin layer of dust like our Moon. Surface dust on other bodies besides the Earth is called “regolith,” the word “dirt” is reserved for our planet, and for surface material that has some organic material. The dirt we’ve got here is partially ground up rock, but also partially decomposed plant and animal matter: organic material.
Both Phobos and Deimos are too small to have atmospheres. In order to have an atmosphere you have to be able to “hold on” to that atmosphere – you have to have enough gravity to keep the atmospheric gasses from drifting off into space. Phobos and Deimos do not have enough gravity to do that. Even Mars loses a lot of its atmosphere to space because it is so small, and it is a lot bigger than its moons.
The temperature on both moons varies a lot. With no atmosphere to mellow out the temperature the daytime side is cold (Phobos was measured at 25F) and the night side is really freezingly cold (-170F on Phobos). I do not plan to visit anytime soon.
Seeing as how we haven’t found any yet, if we do find Martians I’d expect them to be microscopic life forms – bacteria, algaes, or maybe lichens. Anything would have to adapt to using ice instead of liquid water, and be able to be frozen for months at a time.
But, if we toss aside the fact that we haven’t found anything yet and start to think of larger lifeforms we can combine what we know scientifically with our imaginations to come up with what we might have found. Consider:
- Mars has lower gravity than Earth
- Mars has a thinner atmosphere than Earth
- Mars’s atmosphere has more carbon dioxide and less oxygen
- Mars is much colder
- Mars has very little liquid water, so life would have to use ice instead
My dreamed-up Martian would be very tall (because of the lower gravity), have huge lungs (to get enough oxygen), be covered in a thick layer of fat and fur like a polar bear (because of the cold), and would have very warm stomach, so that as it ate ice the ice would melt and turn into liquid water inside.
How would your dreamed-up Martian adapt to these conditions?
Famous Theories on Martian Life
The most famous are all in science fiction – but there was one scientific discovery that caught the limelight for while. It was later determined to be incorrect, but it was exciting anyway.
The meteorite that started it all was called ALH84001 – and a team of scientists announced that they had found evidence suggesting fossilized microscopic organisms inside this meteorite from Mars.
Here is a recent article about Life on Mars, and here is one of the original websites about this meteorite. Bear in mind as you read this one that it is completely out of date, and the shapes that were thought to be fossilized microscopic organisms were determined not to be.
I hope that is helpful!
~ A l i c e !