Old Spacesuits are Potential Satellites

SpaceAdmiral writes "In order to determine if old spacesuits can be effective satellites, the crew on the International Space Station will be throwing one overboard on February 3rd. The SuitSat will transmit information about its condition and, if you happen to have a ham radio or a police scanner, you can tune in when it passes your city! You can use NASA's J-Pass utility to determine when it will pass above you."

Comments

Re:Right.

[Anonymous Coward]

c'mon they aren't that uncommon. Pick one up at your local radioshack for $149.

Re:Right.

[topham]

I do, why don't you?

I have a PRO-2050 (TrunkTracker 800Mhz) from Radio Shack, it support the 149.990 frequency they will be broadcasting on. Most scanners probably do.

Sufficiently low orbit.

[reality-bytes]

IIRC, due to the fairly low orbit of the ISS, anything cast overboard and not subject to a prograde burn will re-enter the Earths atmosphere in a reasonable ammount of time.

Re:Sufficiently low orbit.

[pranay]

True. But the time to re-entry depends heavily on 2 factors: The cross-section of the object (satellite/spacesuit) in the direction of motion and the time of launch.

The cross section decides the drag the object faces. At about 380-400km, which is the altitude of the ISS (and therefore, the ceiling for space-shuttle); the velocity of a satellite is about 7.67km/sec and drag from the thin ionosphere does matter significantly.

The time of launch is relevant because of the 11 year solar cycle, at the peak of which, the sun causes the atmosphere to expand. The expanded atmosphere causes the density at ISS altitude to increase.

If launched today, a small spacecraft with a mass of 30kg and cross section dia. of 1/2 meter would survive for about 3 months before it spirals down to earth.

This is one big reason LEO (low earth orbit) is used primarily for scientific and educational experiments. The low budgets available to researchers cause them to cut costs and inhibit the development of better instruments. A major expense in building a satellite is flight-qualifying it. Which is essentially testing it for thermal, vacuum, outgassing parameters and more importantly, safety to space-shuttle. Since the space-suits have already been in space, they are flight-tested and can bypass all those grueling stages.

Cool, but not very practical

[Rorschach1]

I talked to one of the guys responsible for the payload at a conference a few months ago. It comes down to the fact that they were going to throw an old Orlan suit away anyway, and someone thought it'd be cool to put some electronics in it. But you have to understand that all those electronics were designed and delivered specifically for that purpose, and for the same amount of delivered weight you could probably deploy a standalone microsat. The suit really doesn't add much. Except for the novelty factor, anyway.

Re:Cool, but not very practical

[Anonymous Coward]

The suit really doesn't add much. Except for the novelty factor, anyway.

But the electronics you put in the suit can be off the shelf parts. There's no requirement that the operate in a vacuum, with large temperature differentials, and high rad counts. The spacesuit takes care of that.

For satellites small enough to fit in a suit the cost is not the parts or even the trip to orbit. It's the design and testing because *everything* has to be certified to work in the crazy space environment.

Not a dupe, but...

[Anonymous Coward]

For those who are interested, there's a bit more background about the SuitSat from June.

Re:Space, The Final Landfill

[elgatozorbas]

you have to stop it, you cannot just shove it down, or out, or forward of backward ... it must lose energy

This does not contradict my statement. 'throwing' the suit backwards (as well as down) will lower the suit's speed and thus energy and increases your speed and thus energy.

Example: both you and the suit weigh 1 kg and move at 100 m/s (tangential to Earth because you are in orbit). Neglecting the radial speed you give to the suit (e.g. 1m/s downwards), you will 'throw' it backwards with a speed of 100m/s. The suit now stands still and because of the conservarion of momentum you will move at 200 m/h. This means that your energy has increased and the suit's has decreased.

One could now cunningly remark that you gained net energy because this is quadratic in the speed. The solution to this enigma is that you needed a source of energy to push away the suit in the first place, e.g. a compressed spring that was released. This energy, together with the energy taken from the suit is now in your spaceship.

Re:Waiting for the Hams to protest...

[Anonymous Coward]

But it is. 145.990MHz is in the 2m ham band, designed for exactly this sort of thing, and that's why they put it there. I would have been disappointed if they hadn't put it there, since that's what all my ham gear is optimized to work with.

Really now, I'm starting to wonder just WTF people think ham radio is about. THIS is exactly what it's about. Messing about with RF. I do digital, satellite, etc with it. I do not use microphones or quaint "morse code" keys to talk to people.

Re:Space, The Final Landfill

[njchick]

I'm assuming the relative speed of the object to be negligible compared to orbital velocity, so it's pretty much assured that the object will be burning as slowly as it can.

As for your argument regarding velocity, I have to disagree. Throwing the object back would result in vertical velocity futher due to the part of the Earth gravity that is not compensated by the orbital speed.

Throwing things down lowers the perigee and raises the apogee. Throwing things back lowers the perigee, keeps the apogee and increases velocity at the perigee. With the same perigee (I'm not sure it will be the same), objects with higher apogee will pass the perigee at the higher velocity, this increasing the drag. On the other hand, higher apogee means that the object will spend less time at lower altitudes. Finally, higher apogee will mean longer orbital period, but this is probably negligible.

Now I'm quite sure that the answer is "somewhere in between" :-)

AMSAT has info on Suitsat-1

[kb1cvh]

As an Ham Radio operator, this project is interesting. While a microsat could be deployed, it takes many many man hours to design, build, test and deploy a microsat.

Information about suitsat, which has a lot fewer features then a typical microsat is avaiable here:

http://www.amsat.org/amsat-new/articles/BauerSuits at/index.php

73 de KB1CVH/6