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Domain: tbs-satellite.com

Stories and comments across the archive that link to tbs-satellite.com.

Comments · 9

  1. Re:Cost Versus Utility by korbin_dallas · · Score: 5, Informative · on ISS Construction Resumes

    OK self-correcting my comment.

    Heres a nice table of vehicles:
    http://www.tbs-satellite.com/tse/online/thema_lanc eur.html
    STS is the heavy lifter currently to LEO.

    What I cannot find is size and weight tables of each part of ISS. Not that it matters, the whole ISS plan is DESIGNED around the STS. If it were instead designed around the Proton D1...or Energia.

    Anyway STS is not the only game in town.

  2. Avoidance and tracking, no, but... by brindafella · · Score: 1 · on Old Spacesuits are Potential Satellites

    Okay, so several radar systems track the items and several computer systems analyse the orbital elements.

    However, it is 'space junk' from the time it is sent from the ISS.

    Can anyone predict the orbit of the spacesuit if it is 'thrown' or 'ejected' from the ISS? NO! Any hand-derived force is different any other occasion when a similar mass is trown / pushed. No two throws (vectors) can be the same. Accordingly, the orbit is different, and must be assessed - quickly - in order to have it avoid future launches.

    On 23 Nov 97, another satellite -- Sputnik 40 (Object 24958/97058C) -- was launched (thrown) by hand from the MIR space station during a spacewalk. Batteries lasted until 29 Dec 97, but the de-orbit was much later. In that time, its orbit was refined by use of similar radars as will be used to track the space suits of this story. Please do not expect that the radars and computers will have an 'exact' orbit quickly: That is simply not possible. A 'reliable' or 'predictable' orbit it may be called, but that is not 'exact'.

  3. Re:true but by Shanes · · Score: 2, Informative · on Asteroid Flies Under the Radar, Literally

    As others have pointed out the chances for that hapening are very remote, but anyway, here's an interesting graphic showing the 2004 YD5's position when passing compared to all Low Earth, GPS, and geosynchronous sats. As the page says, it passed 1.88 earth radii from the orbit of GPS satellite BIIA-19.

  4. Re:Nothing new by Jussi+K.+Kojootti · · Score: 1 · on China to Have Over 100 Eyes in the Sky

    Don't want to nitpick, but European spy satellites have been up there for a while already. The Helios program launhed its first satellite in 1995. There are probably other programs too -- I'm no expert, just happened to remember this one.

  5. Re:Nothing new by Jussi+K.+Kojootti · · Score: 1 · on China to Have Over 100 Eyes in the Sky

    Don't want to nitpick, but European spy satellites have been up there for a while already. The Helios program launhed its first satellite in 1995. There are probably other programs too -- I'm no expert, just happened to remember this one.

  6. Re:Question by barawn · · Score: 1 · on SpaceShipOne Flight Completed Successfully
    Lets assume a 3cm thickness cable, that extends from 100km to 300km, centered at 200km. That's a cross-sectional area of 6,000 m^3. Pretty hard to overcome that... that's the sort of cross sectional area of a blimp cutting through the atmosphere's fringes ;)

    6000 m^2, not m^3. Except for the fact that the atmosphere decays exponentially with a scale height of 10 km. So if you wanted to take that into account, the drag would be something like the equivalent of 300 m^2 at 100 km (integral of 6000*e(^-x/10000) from 0-200,000, roughly).

    Plus it's rotating, so its profile is only 6000 m^2 when it's flat against the atmosphere. On average, it's half that. So its profile is 3000 m^2.

    Plus you're not taking into account the differential velocities. At 100 km, it'd only be travelling at mach 3, or 1 km/s, right? Orbital velocity at 100 km is about 8 km/s. That means that, roughly, it's going to experience 64 times less drag than an orbital object at 100 km. I'm not going to take the time to work out all the math, but sufficient to say, I doubt it would be an insurmountable amount of drag. Even 300 m^2 is not much more than the ISS, and the ISS only needs reboosting every 90 days or so.

    It's also important to realize you're talking about fluid flow here, and a tiny, thin piece of ribbon is not going to act the same as a very large flat object - the flow is going to probably be completely laminar, with very little resistance at all. They don't teach drag along with friction because drag is very, very hard.

    I can't think of a single successful space tether experiment thus far.

    Hmm, is this the same experiment? Were there two? This was a Columbia-based mission.

    Although the board found that the tether's insulation was more vulnerable to damage than the experiment's designers had believed, they also found that the problem "is not indicative of any fundamental problem in using electrodynamic tethers." In fact, while the tether was operating it produced currents three times higher than theoretical models had predicted prior to the flight, the board reported.


    As for successful space tethers, SEDS 2, SEDS 1. We'll never know about ProSEDS, since it was cancelled.
  7. Re:Seven minutes in heaven by morcheeba · · Score: 1 · on Flight Testing Of Burt Rutan's X Prize Entry

    Pegasus is a great. You don't even need to own the L1011; the first pegi were launched from a borrowed B52.

    If you check out their record, major problems in 5 of the first 10 launches isn't quite the reliability record I want for a manned flight. Especially since the x-prize requires 2 back-to-back flights - something that didn't happen until flights 7 & 8. The contest also requires reusability, but that's another story.

    p.s. I shared an office with the original glomr... click click click of the tx/rx relays. Ok, it wasn't an office: they put the intern in the lab.

  8. Re:Space Salvage Rights by silentbozo · · Score: 1 · on Astra 1K Communications Satellite now Space Junk

    Nevermind, a simple google search answered my question. The satellite in question is now known as PAS 22, and is owned and operated by Hughes (the salvor, and the original manufacturer.) It originally was supposed to be parked at 105.5E, geostationary, but ended up at 60W after the recovery operation. Two lunar flybys were used, first to stabilize orbit, and the second to improve it.

    The downside of the recovery was that they had to burn off most of the 1700kg of available onboard propellant.

  9. It's been covered... by sweatyboatman · · Score: 2, Informative · on Space Shuttle Endeavour Launches (at last)
    but it's not really news (at least from what NORAD's been saying). It's just a spent SL12 Rocket. Here's some information on this Russian Rocket

    oh, and here's CNN's little piece on it: Lights in the Sky