As I write this, the shuttle Discovery (aka STS-92) is still docked to the International Space Station (ISS). The astronauts have accomplished their mission superbly, and after twelve days in space, I’m sure that they will be glad to return home. The next visitors--early in November in fact--will include the first residents to inhabit the ISS on a permanent basis.

I too welcome Discovery home, and I am glad the manned space program has seemingly found its mission again. The shuttle, after all, is a cargo vessel: in the acronym “STS,” the “T” stands for transport. While recent missions have revived nostalgia for the early days of manned space flight, the shuttle’s raison d’être is the ISS. Something like 100 flights are slated for construction and maintenance. At $250 million a flight, roughly $1 for each citizen of this country, are we getting our money’s worth?

One way to get some "added value" is to add it to your own observing program. And even better, there is no additional cost. When the shuttle, ISS or Russian space station Mir pass above you when it is in sunlight and you are not (that is, the sky is suitably dark), the spacecraft lit by sunlight can be seen from the ground. Those I mentioned are large and hence bright, typically from 2nd magnitude to as bright as Venus. They appear as a slowly moving star, somewhat like a jet aircraft at high altitude. But unlike any aircraft, spacecraft do not have blinking or colored lights (although they can twinkle like stars) nor do they make any sound.

They can appear anywhere in the sky, but the necessary geometry of a sunlit orbiting object with darkened observer means that visible passes occur only in the twilight when circumstances are just right for your location. You can even watch the satellite appear or disappear, passing from or into the Earth’s shadow. If you’ve spent much time outside under the twilight sky, you’ve no doubt seen satellites, even if you didn’t realize what you saw. There are so many satellites up there that several are visible on any given evening or morning.

No specialized equipment is necessary. Just your eyes and an accurately set watch. Get visible pass predictions from the Sky & Telescope (www.skypub.com/sights/satellites/satellites.shtml) and NASA (use "text based sightings" via spaceflight.nasa.gov/realdata/sightings/index.html) web sites. When a good pass is upcoming, the prediction will consist of the date and time, pass duration and maximum elevation, and approach and departure directions. Higher elevations and longer durations are generally easier to see. Good passes seem to come in runs of several days in a row. If it’s not visible tonight, check back next week. You will need to specify your location, but I’ve found it suitable just to use Baltimore or Washington DC predictions and allow a couple of minute’s leeway. If more precision is necessary, you can select from the many cities at Heavens Above Satellite Predictions (www.heavens-above.com). You’re getting pretty serious about sat-spotting when your download your own prediction program and orbital elements. A good overview of what is available is at the Google search engine (directory.google.com/Top/Science/Astronomy/Amateur/Satellites/).

Here on Delmarva, we have an especially good seat for the shuttle’s opening act: the launch. And you don’t even need a computer or sunlight for that matter. On missions to Mir or the ISS, the shuttle is launched into the same, high inclination orbit, tilted about 51º to the equator. On the way into Earth orbit, that trajectory takes it up the US East Coast, from Cape Canaveral to its “main engine cut off” just east of the mid-Atlantic coastline. While the main engines burn they can be seen in a darkened sky, and often the launches are at night. To see a shuttle launch from here, try this: Watch the shuttle lift-off on a cable news channel, and start a timer. Five or six minutes later, go out and look low in the south-southeast. The shuttle will gradually brighten and rise into the east, but only attain 10-12º elevation or so before the cut-off and disappearance from view at about eight minutes after launch. But think about what you’ve just seen: from Florida to here in eight minutes--from a standing start no less! (At right, as seen from my backyard, STS-81 Atlantis streaks into orbit on the fifth Mir docking mission in January '97.)

So welcome home Discovery. I’ve bought my ticket, and I’ll be watching for you next flight...

Moondark is written by Doug Miller and published on the web and in the Delmarva Star Gazers'Star Gazer News. Please address comments and suggestions to dcmiller@dmv.com. This document was last revised on 22 October '00. All text and images copyright © 2000 Douglas C. Miller, All Rights Reserved. This material may not be reproduced in any form without prior permission.