Sen— Astronomers are fighting to save another space telescope project after fears that it faces the axe.
They have mounted a campaign to rescue Athena, a powerful X-ray observatory that promises to boost our understanding of the invisible Universe.
The project is one of three rivals for a major European space mission in the next decade. It is up against Juice, a mission to the moons of Jupiter, and NGO, three spacecraft that would seek to detect gravity waves.
ESA cannot fly all three missions with its current budget. It has 700 million euros allocated for just one project, dubbed the L1 mission of the Cosmic Vision 2015-2025 programme.
A final decision will be made in May as to which is selected. But last week it was leaked that a key advisory committee has come down in favour of Juice, shorthand for Jupiter Icy Moons Explorer.
This is a mission that will fly to Jupiter and visit the Galilean moons Callisto and Europa before finally putting itself in a settled orbit around Ganymede
This has upset hundreds of astronomers who believe that the loss of Athena - it stands for Advanced Telescope for High-ENergy Astrophysics - will leave them without a vital X-ray telescope in the coming years. (They probably also feel that Jupiter has also had plenty of attention from spacecraft. The latest, Juno, is currently on its way.)
No sooner had the recommendation for Juice become known, than a petition was launched by the Athena team, led by Professor Kirpal "Paul" Nandra, a British astrophysicist who is now Director at the Max Planck Institute for Extraterrestrial Physics in Germany.
By last night, 1,345 scientists had signed to argue that ESA should take all necessary steps to adopt the X-ray observatory Athena in the Cosmic Vision programme for operation in the 2020s. This is an instrument that, at around 13 metres long, will only just fit atop an Ariane 5 rocket launcher.
They say a powerful X-ray observatory is an essential part of the suite of facilities expected to be operational in the 2020s, alongside others including ALMA studying (sub)millimetre wavelengths, the James Webb Space Telescope (JWST), the European-Extremely Large Telescope (E-ELT) in the optical and near-infrared, and the Single Kilometre Array (SKA) in the radio band.
The scientists say that Athena is the X-ray observatory to meet the needs of astrophysics beyond 2020, following the success of smaller X-ray observatories including XMM-Newton and Chandra. It would observe a broad range of targets from solar system objects to the most distant in the Universe.