The ISS has a ham radio station on board (callsign NA1SS), and the crew is periodically active making contacts with hams down on earth below. A few days ago I programmed in the ISS uplink/downlink frequencies into the FT-817ND qrp portable radio, and kept an eye on when good passes might be coming over.
The frequencies are:
FM VOICE for ITU Region 2&3: North and South America-Caribbean-Greenland-Australia-South Asia: Downlink 145.800; Uplink 144.490
And I programmed memories into the FT-817ND for doppler shift on the above frequencies +/- 3.0 and 1.5 kHz.
The ISS is in fairly low orbit and moves very fast, so it's only in view for around 10 minutes at a time. Yesterday at around 4:30pm, there was a good pass with the ISS coming overhead, south to north, slightly east of my location here, with a maximum elevation of around 60 degrees. I set up the radio with the Elk log-periodic VHF/UHF on a tripod, and sat in the backyard waiting for the station to pass overhead. Using a netbook computer running the Satellite Tracking module of HRD software, I was able to keep the antenna pointed at where the station was in the sky as it moved overhead. Nothing heard at all at first.
I put out a call every 30 seconds or so -- "NA1SS from KB5WIA near Sacramento" just in case thew crew was listening. After the third call, as the ISS was near max elevation overhead, right away a voice came back with something like "KB5W?A from NA1SS" -- how exciting! The signal was S9-plus, and the audio was so clear I could hear the fans/motors humming in the background up there. I corrected my call, and he came back something like "KB5WIA good to meet you this is Colonel Doug Wheelock aboard the International Space Station NA1SS". I then thanked him for the contact, wished them a happy Labor Day Weekend (what's a long weekend like aboard a space station, I wonder?!), and said I'd clear so he could make some other contacts. I heard around 3-4 more quick QSOs before the ISS dropped below my northern horizon.
Pretty cool for QRP from the backyard!
UPDATE 1: Two days later, I was able to make another (very!) quick contact, and record the downlink audio. Here it is in the attached file: ISS Audio 6 Sept 2010. The file (a one megabyte MP3) is a recording of the entire pass, from AOS to LOS -- intermittently you'll hear Col Wheelock on the ISS talking to various stations. He comes back to my call around 4m18s in the recording, and then makes quite a few more contacts.
UPDATE 2: Here's a link to a photo of Col. Wheelock talking to hams below: http://twitpic.com/2lwwex
UPDATE 3: The QSL card (confirming 2-way contact with the ISS) arrived! Here it is, below:
Great post, in case you haven't seen it take a look at http://www.youtube.com/watch?v=h73EYcyszf8
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