Watch Earth From The ISS

snapman

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Since the dawn of the space age just a few hundred astronauts have joined an exclusive club of humans who have seen Earth from space.

But now you too can join in the adventure thanks to cameras that were recently installed on the International Space Station (ISS).

Nasa’s High Definition Earth Viewing (HDEV) experiment allows you to watch our planet live as the station hurtles around (Click here to watch).

The HDEV investigation placed four different commercial high definition cameras on the ISS.

These were installed on the Columbus External Facility, two identical L-shaped consoles located outside the station in space that host a variety of experiments.

While one of the stated goals of the mission is to assess the ability of such hardware to survive in the vacuum of space, the educational benefits are also plain to see.

The experiment was launched on 18 April 2014 inside SpaceX’s Dragon spacecraft before being installed outside the station on 30 April.

Don’t be alarmed if the screen appears black sometimes – the ISS orbits the Earth approximately every 90 minutes, and about half of that time is spent in darkness while on the night side of Earth.

There is also an occasional loss of signal, but otherwise the stream seems to be operating nominally.

Students in the US helped design some of the cameras’ components through the High Schools United with Nasa to Create Hardware (HUNCH) programme.

Teams of students are also responsible for operating the cameras from Earth as they transmit footage to the ground in real time (track the ISS here).

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On 30 April the High Definition Earth Viewing (HDEV) experiment was installed outside the ISS on the Columbus External Payload Facility. The four cameras on the experiment, view out of one pictured here, stream live video of Earth from the ISS to the ground in real-time.

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The HDEV unit was taken into space by SpaceX's Dragon capsule on 18 April (top left). At the end of the month it was then removed from the rear 'trunk' of the spacecraft by the Dextre robotic arm on the station (bottom left) and then installed on the Columbus module (top right and bottom right)

The cameras used are Commercial-off-the-shelf (COTS) cameras, which are fixed to the station with no zoom, pan or tilt mechanisms.

One of the cameras points down towards Earth (nadir), one points forward in the direction the station is travelling and two look backwards (aft).

The cameras aren’t quite exposed to the full harshness of space, however, as they are enclosed in a pressurised box containing dry nitrogen.

As the ISS moves over Earth the cameras ‘track’ locations below by switching feeds.

Only one camera is operational at any one time but they work in tandem.

The forward camera is turned on for 138 seconds, before switching to the downwards camera for 85 seconds.

The view then switches to the first rear camera for 133 seconds, which also has part of the solar array and two docking ports in its view, before jumping to the other rear camera for 112 seconds.

Then the system resets for 15 seconds and switches back to the forwards camera, and the cycle starts again.

If desired, ground controllers can choose to alter the cycle and switch to a different camera, though, if for example something of particular interest is spotted.

The HDEV experiment is expected to remain operational until October 2015, so you’ll have plenty of time to continue watching Earth live from space.

And later this year a separate endeavour known as Urthecast will be installed on the ISS, which will enable members of the public to zoom and navigate through a higher definition live stream of Earth.

Urthecast say this will let people watch events on Earth unfold in real-time from space.

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As the ISS moves over Earth the cameras 'track' locations below by switching feeds. Only one camera is operational at any one time but they work in tandem as shown in this diagram. If desired ground controllers can choose to alter the cycle and switch to a different camera.

Source: Nasa launches live video of Earth from ISS that streams 24/7 | Mail Online
 
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