Sentinel Costa Concordia

I posted a few months back about the launch of Sentinel 1a, the first of ESA's new Sentinel constellation to go into orbit. Well some data is starting to come back. Here's a not-very-scientific-but-still-interesting example...

After the Costa Concordia incident in 2012, an image was doing the rounds in the newspapers/websites of the wreck from space (possibly from EROS-A?)

That was taken by an optical satellite and unsurprisingly it looks like any digital photograph. Sentinel 1a is different. It is a RADAR satellite so you don't get a 'photo' but rather an image representing the amount of energy that has hit the target and returned to the receiver. This is dependent on the roughness of the object. High scattering should lead to a strong return and in most cases is due to the micro-relief of an object. Bright areas in these images implies high amounts of scattering whereas dark areas mean low scattering. Objects with corners (if you look closely, the side of the Costa is full of them) also give very high returns because they focus most of the RADAR pulse back at the receiver. That's why stealth vessels and planes have such odd shapes and outlines. Aside from being made of materials that absorb RADAR pulses to a certain extent they are also designed to have a low radar profile and channel as little of the radar pulse back to the receiver.

The example i want to show you is of the Costa Concordia, post-refloating, being towed. The image (below) is from Sentinel 1a. You can see the large return from the larger vessel and the smaller returns from the smaller tugs and police tenders.

I also came across another image online (below). It looks like RADAR but the source is unknown. It seems to show the Costa Concordia in a similar position to that in the optical image I first posted. The vessel is on it's side, surrounded by security vessels / rescue craft.

Looking forward to lots more from the Sentinels.