Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Space design
Name: Scott
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: 1991 

Hi I am in Alb. New Mexico and I have a bunch of students entering a Space design contest. I will be posting here and the same set in Engineering and a astronomy, please answer the ones you will and thanks in advance
Space Design Contest Questions
1. What are the Dimensions of nuclear heat and power generators on current o orbiters
2. Other than rotation are there any other ways to falsify gravity? How?
3. Do you use microwaves, TV signals, or radio to communicate with outer spa
4. What is the current speed of an orbiter, given current technology?
5. When they are closest, what is the distance between Earth and Mars?
6. When are they the closest?
7. How far from the surface should the orbiter be?
8. How can aquatic mammals breathe in a water tank?

Well, I can answer 8: aquatic mammals do not breathe underwater: they must surface occasionally to breathe, although some aquatic mammals can stay underwater for incredible lengths of time and number 2: any acceleration will induce weight to mass, it does not have to be rotation. Linear acceleration works as well.

John Hawley

I am not quite sure what you mean by "orbiter" in all this. Do you mean man-made earth satellites, or satellites we have sent to orbit other planets? In any case, the answer to question number 4 does not depend on technology - a satellite orbiting a planet always moves at speed determined by its orbit (unless it is expending energy to stay up there, in which case it would not be an orbiter but just an ordinary rocket). These speeds can be determined by standard equations for orbital motion - let me know if you need more details.

Question number 3: any kind of radiation would work - TV signals are usually also called "radio waves" by the way. The only problem is the radio signals have to get through the atmosphere easily, and of course we also have to have good methods for generating and interpreting the signals. I believe the standard signals used for communication with satellites are somewhat high-frequency radio, but you should get somebody else to verify this.

Question numbers 5 and 6: Earth and Mars have nearly circular orbits in the "ecliptic" plane, so their closest separation is the difference between their orbit radii - the numbers should be in any book on the planets. Their farthest distance is the sum of the two radii, by the way. They are closest every time the earth catches up to Mars in its race around the sun - about every year and a half, I think.

Arthur Smith

Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory