ISS Can Now Watch Sea Traffic From Space

gyrogeerloose writes "During its last mission, astronauts from the Space Shuttle Atlantis installed an Automatic Identification System antenna on the outside of the International Space Station that will allow astronauts aboard the ISS to monitor signals from the AIS transmitters mandated to be installed on most large ocean-going craft. Although these VHF signals can be monitored from the Earth's surface, their horizontal range is generally limited to about 75 km (46 mi), leaving large areas of the ocean unwatched. However, the signals easily reach the 400 km (250 mi) orbit of the ISS. The European Space Agency sees this experiment as a test platform for a future AIS-monitoring fleet of satellites that will eventually provide worldwide coverage of sea traffic."

Why ISS?

[photonic]

Anyone knows what are the advantages of using ISS for this kind of test? I would be interested to see what it costs to send such an antenna up with the shuttle, test that it does not interfere with the rest of the station and train an astronaut to fix it to the exterior, versus just slapping it as secondary payload on some other satellite or even some dedicated micro-satellite that is piggybacking on the launch of a bigger one.

Re:Where else...

[Winkhorst]

They're already watching sea traffic from space. What this does is allow them to quickly remove "legitimate" traffic from the database so they can focus on traffic that's antithetical to the Empire.

Uses?

[Anonymous Coward]

So is this going to be used to find the best spot to crash ISS 2 years after it is completed, just in the unlikely chance that large parts reach the ground?

The orbit?

[argent]

The ISS operates at a relatively low orbit, even for LEO... for example the Iridium constellation is about twice the ISS' altitude (760km vs 350km). They'd have to find a mission that's within the 400km range of the system, and that has room and power to spare.

Re:Where else...

[R3d M3rcury]

Well, it depends on how you do your accounting...

Obviously, it's more expensive to put a space station in orbit in order to test a transmitter. The idea behind ISS, though, is that we pay for it to be up there so that we can put experiments into orbit without building all of the necessary hardware for a satellite. It makes it cheaper for groups wishing to do experiments in orbit because the rest of us subsidize the orbital hardware (ie, the ISS). Because we must supply the ISS, we also subsidize getting the experiments up to the ISS (eg, We need to ship 1000 pounds of food, our rocket will carry 1500 pounds, so we've got 500 pounds that we can fill up with experiments). Because we have to bring things back from ISS (people mostly), we'll carry experiments back to Earth.

So when you include all those in your calculations, the ISS is much more expensive than launching a satellite. However, if you were doing the experiment, it's much cheaper to have the ISS (because governments have already spent the money on the platform and getting stuff up there and back). This, in theory, encourages researchers to consider these experiments because it's cheaper for them.