Space scientists at the University of Leicester have delivered a completely new type of super-lightweight X-ray telescope mirror to study the greatest explosions in the Universe since the Big Bang.
A team of academics, researchers and engineers have designed, built, tested and now delivered a bespoke mirror for the MXT instrument, to be carried on board the Chinese-French satellite observatory SVOM (Space-based multi-band astronomical Variable Objects Monitor).This work was carried out under contract from the French space agency, CNES.
As X-ray telescopes are used to study the most energetic forms of matter in the universe, they must be launched into orbit to avoid the obscuring effects of the Earth’s atmosphere. Traditional X-ray mirrors are very heavy and so are very expensive to carry into space.
This new design allows telescopes to be much lighter than those currently in use, and it also allows vastly wider pictures of the sky to be captured through use of a ‘lobster’ lens, so-called because the design is closely based on the eyes of lobsters.
They focus visible light, not using a lens as mammals do, but by using curved structures of square pores which have reflective interior surfaces. This design, in which the light rays bounce off the reflecting inner pore surfaces at very small angles, can provide a field of view thousands of times larger than a conventional X-ray telescope.
Professor Julian Osborne of the School of Physics and Astronomy at Leicester, who leads the project, said: “This is the first assembled lobster X-ray telescope mirror ever made to fly in orbit.
“This new type of X-ray telescope is in great demand because of their unique light weight and enormous field of view capabilities; they are being studied intensely in both the USA and Europe for new satellite observatories involving the University.”
The new mirror has been built for the SVOM satellite, due to be launched in 2022. The satellite will study gamma-ray bursts, poorly-understood but highly energetic flashes lasting just a few seconds which signify the creation of a new black hole or a highly magnetised neutron star.
These bursts are detectable to the greatest known distances, and so help to identify the very earliest galaxies in the universe as well as helping astronomers answers some of the most fundamental questions about our Universe.
Construction of the mirror required high-precision engineering and extensive X-ray testing of the 25 individual 4×4 cm plates that provide the reflecting surfaces. These glass plates, just a millimetre or so thick, made in France by the Photonis company, are mounted on a lightweight frame using a technique designed to withstand the vibrations of the rocket launch.
The glass plates are made up of a vast number of square pores, which are just four hundredths of a millimetre across. They are aligned to a common focus to give the telescope the best sensitivity to locate new gamma-ray bursts.
The new telescope mirror has been vibrated vigorously, simulating the rigours of its rocket launch, heated and cooled to mimic being in orbit, and then its imaging performance has been extensively verified in Germany before final delivery to the French Space Agency in Toulouse this week.
Dr Jim Pearson, who has led the technical effort at Leicester, said: “A highly skilled team has been needed to do the detailed studies and the precision engineering needed to make such a fine mirror which will survive the rough ride into space.
“This is a world first for Leicester, and I am very proud of the work we have done to make this happen.”
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