Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-l] ISS orbit



air density at height above seal level (h) is given by
density at sea level times a constant (e) raised to the power of a number Z
where Z is given by
the mass of the average gas molecule (m) times gravitational acceleration (g)
times height above sea level (h), all divided by a constant (Boltzmann's constant)
times absolute temperature.

In this model, sunspot activity is applied to raising the molecular temperature and hence velocity proportionately, so that they can reach higher altitudes.

Above about 500 km heating and solar emissions cannot provide enough drag for rapid orbital decay of satellites.

Brian
p.s. This is a rendering of the Tuft's immortal prose into something approaching English.

On 11/15/2011 12:00 PM, Anthony Lapinski wrote:
Thanks for this link -- very informative and detailed.

I guess what I'd like to know is a formula/relationship between air
altitude and density. For example, at what altitude is 99% of the air
below it? Can this somehow be measured, or only the effects from satellite
drag? And what minimum altitude must a satellite be to have no orbital
decay (like a geostationary orbit)?

betwys1@sbcglobal.net writes:
On 11/15/2011 5:10 AM, Anthony Lapinski wrote:
I'm teaching about circular motion and gravitation and mentioned in
class
about the space shuttle and International Space Station. After searching
online, I found that the ISS orbits at an altitude of about 350 km. I
was
surprised to learn that it loses about 100 m each day due to atmospheric
friction, and it has to be boosted to higher orbit several times each
year. I always thought that the atmosphere extended up to about 70
miles,
so how does the ISS orbit decay? And is this true for all orbiting
satellites? Does it have to do with the Sun heating/expanding the upper
layers of the atmosphere? I remember a satellite entered our atmosphere
a
few weeks ago, and the famous Skylab satellite burning up decades ago.

_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l

This note appears to speak to the issue. For some reason it assailed me
with unprecedented soporificity, so I may be mistaken to offer that it
stresses the role of temperature and Solar activity on a satellite
sailing at 350 km altitude.

http://cosmos.phy.tufts.edu/~zirbel/laboratories/Satellite.pdf

Brian W
_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l

_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l