Europe must stand tall on space science

We’re a little bit clearer now in Europe on what the really big space science mission will be at the end of this decade… just a little bit.

For the past four years, scientists and engineers have been developing three concepts that would cost European participating nations about a billion euros. 

IXO will no longer be the giant first envisaged, but still a major leap forward on current capability

To recap, they are: (1) a 20m-long X-ray telescope called IXO that could see the very "edge" of a black hole; (2) a trio of satellites, collectively known as LISA, which might be able to detect the ripples in space-time left by the moment of creation itself; and (3) a spacecraft that would visit the Jupiter system and go into orbit around the moon Ganymede. This one is called EJSM/Laplace.

We were expecting the European Space Agency to give us a good indication this year of which mission might be the favoured one, with the launch pencilled in for 2020 or very soon after.

But as of today, the concepts as we know them – as they were presented to the scientific community in a big showpiece event in Paris in February – are now dead. 

Four years’ work and they’ve hit a big buffer. They cannot be done as originally envisaged.

The reason is the Americans. In recent months, we’ve seen two highly influential reports come out of the States which have attempted to summarise and prioritise current US thinking on space science. 

These reports – they’re called Decadal Surveys, for the obvious reason that they’re done once a decade – have put a mighty spanner in the European works. 

Europe had hoped to progress with one of its Big Three as a partnership with America. 

But the Decadal Surveys do not consider any of these concepts to align with the top-most US priorities in planetary science and astrophysics; and it’s quite clear from the budget situation facing the American space agency right now that there simply isn’t the money on the other side of the Atlantic to participate in them anyway – not at the level that was originally envisaged. Projects like the much-delayed James Webb Space Telescope have consumed huge funds. 

So what is going to happen? 

The IXO, LISA and Laplace teams have been told to go away and think how they could complete their missions as largely European-only ventures. They have just under a year to do this.    

When they come back, their concepts will be smaller and they’ll probably have new names, too. 

De-scoping the concepts and making them work for a billion euros may be easier said than done.  

For Laplace, it looks more straightforward. In technology terms, we already know very well how to send a planetary probe to the outer planets. But Laplace was sold on the basis that it would deliver complementary science to an American orbiter at another Jupiter moon, Europa. If its “cousin” isn’t going…?

For a mission like LISA, a de-scoping is going to involve some head-scratching. 

It planned to fly three satellites five million km apart in an equilateral triangle formation. Laser beams travelling between the spacecraft would measure their separation very precisely.

The idea was that gravitational waves generated by exploding stars and merging black holes would wash over these beams and disturb them in a very characteristic way. 

It’s a new kind of astronomy that would allow you to study far-off phenomena without looking through a telescope. 

With perhaps just a billion euros to play with, the original architecture may not be achievable.  One idea is to still fly three satellites, but use only two laser “arms” to detect gravitational waves. 

Professor Bernie Schutz from the Max Planck Institute for Gravitational Physics, in Potsdam, told me:

"Within the European LISA community, we're kicking around lots of options. In fact, there are so many ideas I think it's pretty clear we will come up with some kind of design. We are asking ourselves key questions: what science can we keep, what will we lose, and are there some new things we could do? I say that because if we shorten the arms, for example, the frequency range changes, and that might open up new possibilities, new observational targets. We're quite certain we can come up with a design that will still make a persuasive scientific case. But it's really too early to say anything for certain."

With a descoped architecture necessarily comes a reduction in sensitivity and capability.  Does LISA remain as compelling a venture as it once did?

This is the question that will face all three of the down-sized concepts when they are presented anew in 2012.

Professor Andy Fabian from Cambridge University, UK, is working on the IXO concept.  He won’t now get the super-scope first envisaged but says the revised X-ray observatory will still be a marvel.  He told me:

”We think we can come up with a mission which is a very significant advance on what we’ve got already. It’s like the next generation of optical telescopes. Initially the European Southern Observatory’s next Extremely Large Telescope was going to be a 100m telescope, and then they went to 42m and now it may be just 30m.  We’ll be doing the same.  We’ll be smaller but we’ll still be bigger than anything that has gone before.  There are now lighter ways to make the mirror; there are higher spectral resolution spectrometers we can use, and also we will try to make this thing more restricted in its instrumentation. The original IXO concept had quite a range of instruments; we’ll probably now only have one or two. We’ll lose some possibilities, but in terms of the core observations – making spectra and images – I think we are going to have an enormous boost compared to what we can do at the moment. I’m quite bullish.”

You can look at the positives to come out of this. It is an opportunity for Europe to stand tall and take a clear lead in certain areas of space science.

What Europe will hope, however, is that at least one of the trio will appear so attractive to the Americans that they will still want to come onboard.

This is not going to be at the levels previously considered, but it could reach $100m or more. Any additional money will mean more capability. There will of course be many US scientists who are deeply disappointed that America can no longer participate in these missions as they had planned; and, as I understand it, efforts are being made to keep them involved for the time being as "observers".

The big cosmic elephant in this room is what Europe and the US decide to do at Mars, but I’ll leave that for my next posting.