Lobsters in Space!

It’s hard to believe that a simple crustacean could be the starting point for a new space telescope, but it turns out that the way lobsters see the world is also a great way for detecting X-rays from space.

Scientists in Leicester are about to send their locally-built ‘lobster eye’ into space on Europe’s upcoming mission to Mercury, BepiColombo, scheduled for launch in October 2018.

In this blog we delve into the quirky ways that lobsters, and now space telescopes, capture light.

What are X-rays?

X-rays are a very high energy type of light that come in two categories: hard and soft, and they form part of the electromagnetic spectrum.

Because of their huge energy, X-rays can easily pass through everyday materials, which is why they are used in the medical profession and in airport scanners.

However, this also makes them extremely difficult to detect using conventional mirrors or lenses since they pass straight through these objects undetected.

Why look at space in X-rays?

X-rays allow us to study hot celestial bodies like our Sun, black holes, and galaxies.

At extreme temperatures of around 999,000°C these objects are so hot that they emit copious amounts of X-rays. By studying these X-rays we have begun to understand how our universe began and grew over time, how stars live and die, and about the presence of supermassive black holes that lie in the centre of galaxies.

In order to detect X-rays from space, we need our telescopes to be above Earth’s atmosphere. Our atmosphere absorbs most incoming X-rays, which is good news for us, but bad news for X-ray astronomers!

Because X-rays have so much energy and can penetrate through materials, they can only be detected by very, very gradually focussing them onto a detector.

In a conventional X-ray telescope (like XMM Newton) this means very long, cylindrical mirrors that are nearly parallel to the incoming X-rays.

But big mirrors mean a big and heavy telescope, which requires more rocket fuel, which increases the cost of the mission.

So there’s a big advantage to creating a lighter, smaller way of capturing X-rays from space.

Lobster eyes

This is where lobsters come in!  A lobster’s eye reflects incoming light rays instead of refracting (i.e. bending) them like human eyes do.  Each lobster eye is made up of around 10,000 small square tubes called facets, which have reflective inner walls.

These facets reflect light rays and concentrate them at the same point.

In 1970, Roger Angel at the University of Arizona proposed that the workings of a lobster eye could be transferred to technology for the use of X-ray telescopes.  It was at this point George Fraser at the University of Leicester led a research team to develop the technology further.

It is now known as Micro-pore Optics and Silicon-pore Optics, depending on how the tubes are made.

“Lobsters and similar animals use reflecting mirrors to focus light in their eyes, unlike the lenses used by people,” said Professor Julian Osborne, who is one of the scientists leading this work at Leicester. “We can make man-made Lobster-type mirrors with the very high degree of smoothness needed to focus X-rays, and make them robust enough to survive the rigours of a rocket launch .”

This new technology isn’t just bound for space.  By reversing the technology we can create parallel beams of X-rays that can be used as airport scanners, cargo scanners, and even for bomb detection in the military.

We can also use the same technique of micro channels to analyse and monitor biological material; this could help evaluate the effectiveness of certain treatments of bladder cancer, as one example.

Leicester pioneers

The University of Leicester has been at the forefront of X-ray telescopes and the development of the lobster technology.  This includes the first ever X-ray telescope bound for orbit around another planet, BepiColombo bound for Mercury. On board BepiColombo is MIXS (Mercury Imaging X-ray Spectrometer) which was designed, built, and tested in Leicester.

The main objective of MIXS is to provide the most detailed map of the Mercury’s surface and what it’s made of. Hopefully we’ll begin to understand how Mercury formed and the interaction of the solar wind with Mercury’s magnetosphere and exosphere.

The Leicester lobster eye will also be launched on an upcoming spacecraft called SVOM, that will look for gamma-ray bursts and other powerful explosions across the universe.