# Splash mechanics on Mars

• Yoni

#### Yoni

They found an underground lake on Mars last week!
Given that the lake exists and is actually liquid (and has a surface), two obvious questions come to mind:
1. Will I be able to beet my earthly current record in bouncing a pebble there?
2. If I release a pebble from a given height here and there, which splash will be higher?

Cheers to space exploration!

They found an underground lake on Mars last week!
Given that the lake exists and is actually liquid (and has a surface), two obvious questions come to mind:
1. Will I be able to beet my earthly current record in bouncing a pebble there?
Do you mean "skipping" a pebble? What record do you mean here -- number of skips or distance travelled?
The gravity on Mars is only 38% of the gravity here on Earth (http://coolcosmos.ipac.caltech.edu/ask/73-How-strong-is-the-gravity-on-Mars-), so a rock would travel farther after each skip. As far as the number of skips, I don't know how the lower gravity would affect this.

As on Earth, you would not want to use a pebble, but would want to choose a rock with a flat surface. As English is probably not your first language, a pebble is a small stone, typically roundish. A good skipping stone would tend to be larger than a pebble.
Yoni said:
2. If I release a pebble from a given height here and there, which splash will be higher?
Seems pretty obvious to me that with lower gravity on Mars, the splash from a pebble would be higher there.

Will I be able to beet my earthly current record in bouncing a pebble there?
I assume you mean "beat" and "skip", not "beet" and "bounce". Given that Mars has about 1/3 the gravity of Earth, I don't see how you could not beat the record but there are some complications. You'd have to be wearing a spacesuit so your throwing ability would be limited. THEN of course, there is the real killer which is that it is about a mile underground which is REALLY going to complicate rock skipping

I did mean "beat" and "skip", and I guess our pebbles here are flatter than yours... :)
In any case, while it is trivial that the distance would be longer, My first guess was that the mean number of skips would not depend on gravity (if all other factors are similar).
Regarding the height of a splash: Let's take it to the extreme. In very low gravity, surface tension completely governs the process. The rock would meet the water with very low velocity and the surface tension would pull it into the water, and I would presume make no splash at all.

My first guess was that the mean number of skips would not depend on gravity (if all other factors are similar).
That's a good point. I had not looked at it that way, I was just thinking of the distance.