snowdog@athena.mit.edu (Richard the Nerd) (11/19/88)
Hi folks, Since the Atlantis launch is pretty well(??) fixed by now, we figured it's about time to run a visibility window check on it, just so that everyone knows when and where it will be visible during nighttime passes. I have here a semi-coherent set of results from our calculations. If any of you are interested in seeing the shuttle but have no prediction software or source of elements, give me a shout. As some of you know, I wrote lots of software to handle just this kind of thing and I run a mailing list of satellite predictions for many of you around the world. So if any of you would like to observe the shuttle, or any other satellites, send me your: 1. Location name 2. Latitude and longitude, down to (at least) tenth of a degree 3. Elevation above sea level (not too critical) 4. Time zone (important) 5. Daylight Savings Time rules 6. Satellites you would like to see 7. Questions you may have (these are welcome!) And I will put you on the mailing list. One interesting point about the shuttle: I am informed that they will be deploying a KH-12 and that they will be testing the satellite before it changes into its final orbit (of perhaps h=400km, i=70 deg, eccentric). If they find something wrong, they will bring it back down. Anyhow, this means that the KH (which is pretty huge) will be in the immediate vicinity of the shuttle for quite a while, making a specacular sight for those who make the effort to see it! Anyway, here are the visibility conditions. In making these up, we assumed: 1. LAUNCH TIME: Dec 1 1988, 1130-1430 UTC. Luckily, if the launch gets delayed the visibility dates won't change much, so you can still use them (by adding the number of days the mission was delayed to each visibility date). In the event of a big delay I will post an update. 2. INCLINATION: 57 degrees 3. ORBITAL HEIGHT: 340 km. This was based on the historical records of previous DoD missions, and is pretty uncertain because of the many unusual factors about this launch, like launching a spysat that was meant to be launched into a heliostationary orbit from Vandenberg. (Anyways, there is about another pages' worth of deductive reasoning we did which is not particularly interesting because it does not confirm anything.) As a general rule: If the height is bigger than that, the windows will expand. If it's lower, they will contract, sometimes drastically (bad news!). Some of the below windows cover intervals not included in the mission as it is scheduled now, but of course they might if the mission gets delayed. For people about 40deg N, the general picture is this: If they launch early _or_ late in the window, we'll see it; if they launch it in the middle of the launch window we are screwed. The launch window on the first of December is 1132-1432 UTC. Remember, the data below will still be us able if the launch is delayed, even by as much as a week; you will, however, have to add the number of days the launch was delayed to all dates. Here are the more quantitative data. The calculations were done for a launch at various points in the launch window, spaced in intervals of 30 minutes. Once you know the launch time (after launch, nothing is certain before!), you can pick the one closest to that time and that will be the correct visibility window summary. Any comments, questions, etc. are welcome; but please don't expect an extremely prompt reply. I am unfortunately rather busy with schoolwork (and it's stuff like quantum physics instead of orbital mechanics - nuts!). I will hopefully get to answer your stuff over the weekends. Here are the data: ASSUMED LAUNCH TIME: 1130 UTC. Place (latitude) Visible in the morning Visible in the evening Australia Nov 28 - Dec 2 none 30 deg N Nov 30 - Dec 4 (great!) none 40 deg N Dec 1 - Dec 23 none 50 deg N Dec 2 - Dec 18 none 60 deg N Dec 4 - Dec 18 none ASSUMED LAUNCH TIME: 1200 UTC Place (latitude) Visible in the morning Visible in the evening Australia Nov 28 - Dec 3 none 30 deg N Dec 2 - Dec 5 none 40 deg N Dec 2 - Dec 7 none 50 deg N Dec 3 - Dec 24 none 60 deg N Dec 6 - Dec 20 none ASSUMED LAUNCH TIME: 1230 UTC Place (latitude) Visible in the morning Visible in the evening Australia Nov 30 - Dec 4 Nov 28 - Dec 2 30 deg N Dec 3 - Dec 7 none 40 deg N Dec 4 - Dec 9 none 50 deg N Dec 5 - Dec 26 none 60 deg N Dec 7 - Dec 21 none ASSUMED LAUNCH TIME: 1300 UTC Place (latitude) Visible in the morning Visible in the evening Australia Dec 2 - Dec 6 Nov 29 - Dec 3 and no windows at all for northern hemisphere (bummer!) ASSUMED LAUNCH TIME: 1330 UTC Place (latitude) Visible in the morning Visible in the evening Australia Dec 3 - Dec 7 Nov 29 - Dec 3 30 deg N none Nov 26 - Dec 2 40 deg N none none 50 deg N none none 60 deg N none none ASSUMED LAUNCH TIME: 1400 UTC Place (latitude) Visible in the morning Visible in the evening Australia Dec 4 - Dec 8 Dec 2 - Dec 6 30 deg N none Nov 28 - Dec 3 40 deg N none Nov 25 - Dec 2 50 deg N none none 60 deg N none none ASSUMED LAUNCH TIME: 1430 UTC Place (latitude) Visible in the morning Visible in the evening Australia none Dec 3 - Dec 7 30 deg N none Nov 29 - Dec 4 40 deg N none Nov 26 - Dec 4 50 deg N none Nov 8 - Dec 3 60 deg N none Nov 11 - Nov 30 That's all! Hope to hear from you, -Rich "Cruising on your radar, Watching from the satellites Take a page from the Red book And keep them in your sights..." -RUSH- Early Distant Warning