This is an interesting idea for a project, but it's probably too difficult to do without lots of help. Mars is a very deadly place, so trying to simulate conditions on Mars can be dangerous too.
Okay, enough warnings. Here are the vital statistics for Mars's atmosphere:
| Pressure | 7 millibars (.7% Earth's) | |
| Temperature | max | 27 C (80 F) |
| average | -55 C (-67 F) | |
| min | -133 C (-207 F) | |
| Composition | 95% carbon dioxide | |
| 2.7% nitrogen | ||
| 1.6% argon | ||
In addition, Mars's thin atmosphere allows a great deal of cosmic rays and ultraviolet light to reach the surface. I can't find the exact numbers at present. Don't try to simulate Mars's radiation environment: it's far too dangerous.
How might you go about simulating Mars's atmosphere? Well, first you need a container. I believe a thick-walled glass (Pyrex!) bottle will hold up to the pressure: if you don't care about being able to see inside, a steel container would be safer. It needs to be very strong, and have only one opening which is as small as possible (to prevent leakage). You want to use as small a bottle as you can: it'll be stronger, and easier to create a vacuum. A rubber stopper should provide a good enough seal.
The bottle needs to be filled with carbon dioxide gas: there will probably be some nitrogen left over from remainders of the Earth air left in the bottle; the argon is very difficult to get, and not worth the trouble. Leftover Earth air will probably contaminate the inside of the jar with too much oxygen, but that's too hard to fix. The best source for carbon dioxide is dry ice. Warnings about handling dry ice follow...
To create the low pressure, you should be able to use a hand- operated vacuum pump, available for $10-$20 or so from Edmund Scientific and other places. Be sure to get one with a vacuum gauge so you know when you get to the right pressure. An easier alternative is a mechanical electrical vacuum pump, which runs a few hundred dollars.
The final problem is the low temperature. Dry ice vaporizes at about -78 C at Earth's atmospheric pressure. So you should be able to use it to cool the Mars jar as well as to fill it with CO2. However, this isn't very helpful unless you know what the temperature is. A mercury thermometer won't work at these cold temperatures. You'll probably need a thermocouple thermometer; the cheaper ones work down to -60 C or so, which is close enough. They're available for about $60 from Hanna Instruments, though most good chemistry labs will have one.
I insist that you work with a teacher who knows about the dangers involved here. The main risks are getting burns from the dry ice, and having the bottle break due to the cold or the pressure. Do not touch dry ice or any glass or metal objects in contact with dry ice with your hands. The first time you try this experiment, wrap the bottle with many layers of strong cloth (towels or blankets) to prevent shattering in case the bottle breaks.
A rough idea of the procedure: Clean and dry the bottle thoroughly. Put a small (pea-sized) lump of dry ice in the bottle. Stick a metal or glass tube through one hole of a two-holed rubber stopper, and the thermometer's probe through the other hole. Stopper the bottle and attach the pump to the tube. Place the bottle in a styrofoam cooler, and fill the cooler with dry ice. Start pumping out the bottle. As you pump out the air, the dry ice lump will vaporize, filling the bottle with carbon dioxide. Keep pumping until the dry ice is gone. (You can tell when this happens, because you'll suddenly be able to pump down to lower pressures than before. If this takes forever, try again with a smaller lump of dry ice.) Check the temperature and pressure to make sure they're in the Mars range. Gas will slowly leak into the bottle (but if the bottle top is below the top of the cooler, the gas leaking in will be mostly carbon dioxide) so you'll have to work the pump occasionally to keep the pressure down.
Aha! It just occured to me that you can make your life easier by pumping out the bottle before you pack it in dry ice. The pressure will drop automatically as the air inside cools. The only trouble is you have to guess beforehand when to stop. (actually, you can calculate it using the Ideal Gas Law).
What can you do with a Mars jar? Well, the obvious thing to do is to see what happens to Earth life in such an environment. Try putting a small flower or leaf, or a drop of water in the jar before pumping it out, and leaving it there for several hours. You may find it takes more pumping, because gases will be released from the plant's tissues. Do not put animals in the jar. You will kill them, slowly and painfully. Experimenting on animals in this fashion is pointless cruelty, not science.
The October 1996 issue of Scientific American contains useful information about amateur vacuum apparatuses. You don't need to generate the high vacuum discussed there, so you can skip the liquid nitrogen and the molecular sieve. But the aluminum plate and canning jar setups are very good ideas. And you definitely want to cover the glass with a plastic bottle as a blast shield!