Time to choose a billion-euro space mission

NGO schematic NGO would study the gravitational waves emanating from interacting supermassive black holes

It's an important week for European space science.

A key committee that advises the European Space Agency (Esa) is meeting to choose a preferred billion-euro mission to launch in the early 2020s.

They have three exciting concepts in front of them.

  • Juice - a mission to Jupiter and the Galilean moons
  • Athena - the biggest X-ray telescope ever built
  • NGO - a trio of high-precision spacecraft to detect gravitational waves

In terms of scope, all three missions now carry significant differences from how they were originally envisaged.

Important revisions were forced on the designers when the Americans abruptly announced in April last year that they would no longer participate.

The US space agency (Nasa) said it had different programmatic priorities and, in any case, was struggling to find the money to take part.

That bombshell was delivered after the joint mission study groups had already completed four years of feasibility work.

It meant the European members of those teams had to hurriedly reassess their ideas to make them fit within a much more constrained financial envelope.

Esa has in the order of 700m euros to spend on a "large class" mission. This covers the cost of building and launching a spacecraft. With individual member states covering the cost of the instruments on board, the total overall budget should emerge somewhere around the billion euro mark.

The agency's Space Science Advisory Committee (SSAC) has been poring over the detail of the revised mission concepts, hearing the last-chance advocacy from the competing teams on Monday.

The committee will deliver its considered recommendation to Esa's executive after some final deliberations.

That's not quite the chequered flag, however.

The executive needs to satisfy itself that the preferred candidate does indeed tick all the boxes on technical risk and cost; but assuming the directors are happy, the chosen concept will be handed to member-state delegations for the final say in early May.

It is on the conclusion of that meeting - the Science Programme Committee - that Esa's big mission for the 2020s will be announced; although I'll be somewhat surprised if the name of the SSAC's preference isn't in wide circulation by the end of this week.

So, the candidates are:

Juice (Jupiter Icy Moons Explorer): This is the concept that has probably been least disrupted by the decision of the Americans to walk away.

Juice concept Juice would be the first satellite to orbit an icy moon - Ganymede

It envisages an instrument-packed, near five-tonne satellite at launch that will be sent out to the largest planet in the Solar System, to make a careful study of three of its moons.

Juice will use the gravity of the gas giant to initiate a series of close flybys around Callisto, Europa, and then finally to put itself in a settled orbit around Ganymede. The emphasis will be on "habitability" - understanding the unique nature of these fascinating worlds and whether there is any possibility they could support life in some way.

"Its mission goal is to be the first spacecraft to go into orbit around an icy satellite," said Andrew Coates, a science team member from the Mullard Space Science Laboratory in the UK.

"Ganymede is a fascinating target. It has a magnetic field - the only moon in our Solar System that has one. It's also the biggest moon in the Solar System. It's a very exciting target because we know it has a liquid water ocean beneath its icy crust. So, part of the mission is to characterise that ocean better."

Athena X-ray telescope: We've had some very capable space observatories in the past looking at high-energy emissions coming to us from across the cosmos. Two of the them - Nasa's Chandra telescope and Esa's very own XMM-Newton telescope - continue to return excellent science.

Athena concept Athena is being billed as the high-energy complement to the James Webb telescope

But Athena will dwarf these machines in terms of size.

"The focal length is 12m. That would make it the biggest X-ray telescope ever built. It is as big as we can get inside an Ariane 5 rocket," said Prof Richard Willingale from Leicester University, which would hope to be involved in the project if it flies.

"It's actually two telescopes in one, with a fixed instrument on the end of each telescope.

"It will be the high-energy astrophysics version of the James Webb Space Telescope [which will observe the Universe at much longer, infrared wavelengths]. We will see things that they can't.

"Primary targets would include active galactic nuclei and the black holes at the centre of them - essentially the first black holes. For the sources out there that are producing X-rays - basically, this will be a new era."

NGO (New Gravitational wave Observatory): Formally known as Lisa, this concept has had a very long gestation.

It describes three satellites, separated by a distance of a million km, which will form a high-precision interferometer.

Lasers running between the "mothership" and two outlying daughter craft will measure the very fine changes in distance between free-falling blocks inside the spacecraft.

Disturbances in these length measurements would signal the arrival of gravitational energy emitted, for example, from the interaction of supermassive black holes at the centres of colliding galaxies. It's physics at the extreme.

"The laser arm length is somewhat reduced compared with the original Lisa concept, but NGO preserves most of its science," said Prof Jim Hough from Glasgow University, which has had a major input into the design.

"NGO allows us to look at black-hole physics in a way that no other mission could easily do. It's real new science.

"NGO will work beyond the wavelengths of ground-based observatories. We can't study supermassive black holes with them in the way we'd be able to with these spacecraft. And, of course, there'll be very many tests of general relativity in what is a very extreme gravitational regime."

Jonathan Amos Article written by Jonathan Amos Jonathan Amos Science correspondent

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  • rate this

    Comment number 15.

    What is the point in space exploration? We have so many problems here on earth, all caused by technology, not least of which is climate change that will wipe us out in the next few decades if we do not stop now. As for moving into space due to increasing population, would it not be far easier for us to simply manage our population size?

  • rate this

    Comment number 14.

    I still think Juice is the best option of the three, with Athena a close second. Though its actually a pretty narrow margin between all of them and I don't envy the people having to make this decision.
    Juice is the one that pushes us the most towards actual physical space exploration and should produce a lot of new and very interesting results. Only a lander would be better.

  • rate this

    Comment number 13.

    NGO of course! The mission must complement programs on earth like LHC at CERN (where many countries spent $$$$$$ and taxpayers got only vague confirmations of the Standard Model) and it must lay the groundwork for future science.
    .. NGO is the best choice as it will be hugely important for Cosmology, Quantum Mechanics etc. After all, Europe is the home of Copernicus, Galileo, & Einstein.

  • rate this

    Comment number 12.

    I would personally welcome any Jovian mission; especially one that had aims to harvest the power in that area, Jupiter has abundant sources of Hydrogen for example-given the right tech, we could utilise this and use it as a non-polluting fuel on the ground. With any scenario however, I think that it will be a good 50 years before governments begin to seriously consider the possibilities in Space.

  • rate this

    Comment number 11.

    Choose Juice. Time spent in reconnnaisance of places we will go to ourselves one day is never wasted.

    Second choice is Athena. I wonder what a Bussard ramjet would look like at X-ray wavelengths?

  • rate this

    Comment number 10.

    As has been said by others, much as I love the idea of high-technology space science, I'd much rather see a foundation for high-technology space habitation, and exploring the moons of Jupiter seems the best bet for this. Still, any of the three will be exciting enough to watch develop, and with luck I'll lend a hand!

  • rate this

    Comment number 9.

    All these super powers in the EU yet we can only afford 1 of these yet spend over 50billion a year on helping farmers. Not only should all 3 projects go ahead but esa should also have a manned space program.

    UK,Germany,Italy,France,Spain you would of thought be uber powerful together and be on mars with new propulsion systems, apparently not!

  • rate this

    Comment number 8.

    Basic science is not of immediate use to Earthlings. Juice will make discoveries that change the priorities of space research for years

    Ganymede is a future colony and its ocean might have huge surprises about exolife

    Miniaturization will allow the mission to grow over the next few years. Imagine a 3D printer that "prints" a rover station “ONSITE”.

  • rate this

    Comment number 7.

    We need to stop making these individual satellites for billions and start building a more lasting deep range ship equipped with all the latest we have in terms of science. When a new experiment comes along it can be sent up as a module or addon to be used.

    This would start to reduce wasted equipment that works perfectly apart from it ran out of fuel. We need to think long term.

  • rate this

    Comment number 6.

    JUICE with a lander seems the most appealing, say for Europa or Ganymede. But to be honest ESA should be going for a mission that the US isn't currently researching or running, so to seem more unique with their ideas, so Athena or NGO (a follow on from LISA Pathfinder). Out of those 2, Athena would be logistically the easiest and the most challenging to build. Hope the UK gets seriously involved!

  • rate this

    Comment number 5.

    I'd hope to see all of these happen! For all of those who say w cannot/should not afford this i'd suggest we stop spending on junk foodand weapons first...

  • rate this

    Comment number 4.

    While space activity is always viewed as a scientific endevour, it is nothing of the sort. It is the first step in a series of a zillion steps leading eventually to the evacuation of the planet before the Sun makes life on Earth impossible - every step into space now must be looked at from that point of view, although this may sound crackpot, we cannot afford not to!

  • rate this

    Comment number 3.

    If we really want to show we the EU are into true space fare. By the year 2025, we should have sub-surface probes sent to every moon/asteriod/plutoid etc that has water in the entire solar system! Anything less is just playing games...

  • rate this

    Comment number 2.

    I vote Juice. Human beings are eventually going to have to move offworld as the population over the next 300 years to going to become totally unsustainable (it is already at some limits). Stephen Hawking advises this. Any knowledge that we can gain in aiding our understanding of other planets and potential colonization would be money well spent. Perhaps not Ganymede specifically.

  • rate this

    Comment number 1.

    It's been 40 years since we stood high on the moon and let Space know we're coming. In this age of technological advancement we should be aiming for the next stepping stone. However we also must admit that 40 years is not a very long time when talking about going one step further than the Moon, it's quite a big one especially if the next step is Mars. One day we will get up there, just you wait.


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