The International Space Station will be passing over the Tri-Cities area in the mornings and evenings over the next few days. If you’ve never seen the ISS, or if you haven’t seen it in a while, try to get out and take a look. The space station is bigger and brighter than ever, easily the brightest thing in the sky when the conditions are right.
NASA astronauts have taken to calling the ISS by the call sign or nickname Alpha.
ISS in June, 2008. Courtesy NASA.
Look for Alpha to rise out of the haze Friday 18 July in the west-southwest at 11:22 pm and pass almost directly overhead. But don’t be late, Alpha will be out of sight in the northeast by about 11:28 pm.
Alpha will be visible passing over our area several times on Saturday July 19, twice in the early morning hours, and twice in the evening. On these passes, it won’t be quite as bright as on Friday.
On Saturday morning, watch for Alpha in the northwest beginning at 4:10 am, then again, after one orbit, in the west at 5:45 am. On Saturday evening, watch for Alpha in the south-southwest beginning at 10:11 pm, then again in the west at 11:46 pm.
On Sunday 21 July Alpha will be making two very bright passes high overhead: in the morning, watch for it to rise in the west-northwest at about 4:33 am; in the evening, watch for it in the west-southwest at about 10:34 pm.
There are several websites you can turn to for updates and more detailed information about spotting the ISS and other satellites. The simplest is http://spaceweather.com/flybys/. You’ll need only a zip code to get up-to-date satellite flyby predictions. A more complete database is available at http://heavens-above.com/. To use heavens-above you’ll need to select your viewing location from a database, and, if you like, you can register as a user and save your preferences.
The ISS orbits the earth once every 91 minutes at an altitude just over 180 miles. To stay in orbit the station clips along at just over 17,000 mph.
The station doesn’t need motors to keep moving and stay aloft. Once a new station part is launched into orbit above earth’s atmosphere by a NASA space shuttle or a Russian or European Space Agency rocket, the part continues to coast along at the proper orbital speed.
The ISS does experience a slight bit of air drag in low-earth orbit, and because of this its orbit slowly decays. To keep the station aloft, visiting supply and servicing spacecraft give it a boost from time to time.
ISS Altitude. From Heavens-above.com.
Presently, the ISS is about 60% completed. It is now about the size of a football field, its profile is dominated by a number of large, shiny solar panels. The panels generate all of the space station’s electrical power and are the reason why — when sunlight glints off them just right — Alpha appears so bright.
The total weight that has been lifted into orbit to build the ISS now exceeds 600 thousand pounds. The volume of living space aboard the ISS is now about 15 thousand cubic feet, about the same as a two-thousand square-foot home (with eight-foot ceilings).
When you see Alpha pass overhead be sure to wave to the two Russian cosmonauts and one American astronaut that presently call it home. Commander Sergey Volkov and Flight Engineer Oleg Kononenko have been aboard since April, 2008 and Flight Engineer Gregory Chamitoff has been aboard since just last month when the space shuttle Discovery visited the station.
NASA astronauts Greg Chamitoff (left), Garrett Reisman, both Expedition 17 flight engineers; Russian Federal Space Agency cosmonauts Sergei Volkov, commander, and Oleg Kononenko, flight engineer.
