Countdown on hold pending orbital calculations…

Meg Travers Wednesday, January 18, 2012 - 15:15

If you’re interested in the City of Light event, you’ve probably noticed that we are a little vague about the TIME contact will occur with the International Space Station (ISS). Small but incredibly important detail – how could we have missed this?

The truth is, we don’t yet have a confirmed time the event will take place! Last week, ARISS booked us the time of 1822hrs (6:22pm) on the 20th, however on Friday night, the ISS had to fire its engines to avoid some space debris that could otherwise have collided with it. That firing of the engines has moved our contact time to 1810hrs (6:10pm)

Compounding this is the ISS solution to orbital decay. Anything orbiting the Earth gradually gets closer to the planet – it’s an effect of the Earth’s gravity. To combat this, from time to time, NASA boost the height of the ISS either using the stations onboard engines, or the engines of the resupply ships that visit it regularly. The ISS is scheduled to be boosted on 15th February, and they aren’t able to confirm how much this might change the orbit and our contact time until after this is done. Whilst it should only alter the time by =/- 10 mins, once they’ve confirmed the time, we will update our information about the event to let you know.

You can look at the currently published orbital predictions on the NASA website and you can see a plot of the heights of the ISS from 1998 to 2009.

The astronauts are scheduled to wake up at 3pm (Western Australian time) on the day of contact – 20th February – so while it will be late afternoon or early evening for us when we speak to them, on the space station it will still be morning. However, between waking up and talking to Perth, they will have orbited the planet twice!

Meg Travers
Digital Archive Support Manager