Hi,

I think it would be very difficult to make a homemade satellite, build a rocket to launch it into space yourself, and receive data from it on the ground. A lot of complicated electronics go into even the most basic satellites and launching satellites into space is very expensive. You also need permission from the government to launch anything into space. This is really important because the launch of a large rocket could be mistaken for a missile attack.

I don't know what the lowest satellite orbit ever used was, but I do know that the altitudes at which satellites orbit is limited by the extent of the Earth's atmosphere. The problem is that if you tried to put a satellite in a very low orbit to study something like the Earth's ionosphere, the drag caused by the atmosphere would cause the satellite's orbit to decay very quickly. It could be dangerous if a satellite re-entered the Earth's atmosphere over a populated area. This is part of the reason why NASA has a sounding rocket program to study the ionosphere. Sounding rockets can carry a scientific payload into the ionosphere to take measurements for a short time before the payload re-enters the atmosphere. Sounding rockets are very important to helping us understand the aurora and ionospheric phenomena that occur at lower latitudes. Sounding rockets have also been used to study things like sprites and jets that occur above huge thunderstorms. Right now, I am analyzing data from the Langmuir probe on a sounding rocket called ACES that was launched from Poker Flat, Alaska in 2009. The Langmuir probe is used to measure the electron density in the ionosphere.

I don't know if they are the smallest satellites ever launched, but a CubeSat is only 10x10x10 cm (or 4 inches on a side) and weighs about 3 pounds.

Kris

You can read more about CubeSats here: http://www.nasa.gov/direc...Sats_initiative.html

You can see photos of the payload integration and testing of the ACES rockets here:

http://sites.wff.nasa.gov...nds/indexGallery.htm

More info about the ACES rockets here:

http://www.space-travel.c...Auroral_Arc_999.html

A video of the ACES launch here:

http://www.youtube.com/watch?v=1Rke1bfqzBk

And my co-worker Scott talking about rocket instruments here:

http://www.youtube.com/watch?v=ur1iV-KiWM0