Euclid telescope to probe dark universe

Euclid (Esa) Euclid will conduct its surveys 1.5 million kilometres from Earth on its "night side"

Europe has given the final go-ahead to a space mission to investigate the "dark universe".

The Euclid telescope will look deep into the cosmos for clues to the nature of dark matter and dark energy.

These phenomena dominate the Universe, and yet scientists concede they know virtually nothing about them.

European Space Agency (Esa) member states made their decision at a meeting in Paris. Euclid should be ready for launch in 2020.

Esa nations had already selected the telescope as a preferred venture in October last year, but Tuesday's "adoption" by the Science Programme Committee (SPC) means the financing and the technical wherewithal is now in place to proceed.

The cost to Esa of building, launching and operating Euclid is expected to be just over 600m euros (£480m; $760m). Member states will provide Euclid's visible wavelength camera and a near-infrared camera/spectrometer, and its ground and data-handling elements, taking the likely cost of the whole endeavour beyond 800m euros.

The US has been offered, and will accept, a junior role in the mission valued at around 5%. The American space agency (Nasa) will pay for this by picking up the tab for the infrared detectors needed on Euclid. A memorandum of understanding to this effect will be signed between the agencies in due course.

Prof Bob Nichol: This is a big deal for Europe and the UK

"We have negotiated a detailed text with Nasa, which both parties consider final, and it is ready for signature," said Dr Fabio Favata, Esa's head of science planning.

"It will mean a small, commensurate number of US scientists will be welcomed into the Euclid Consortium," he told BBC News.

The consortium is the team that will have access to Euclid's data.

The adoption also will now trigger the release to industry of invitations to tender. Europe's two big space companies - Astrium and Thales Alenia Space - are certain to bid to build Euclid.

Dark energy and dark matter mysteries

Dark matter distribution simulation
  • Gravity acting across vast distances does not seem to explain what astronomers see
  • Galaxies, for example, should fly apart; some other mass must be there holding them together
  • Astrophysicists have thus postulated "dark matter" - invisible to us but clearly acting on galactic scales
  • At the greatest distances, the Universe's expansion is accelerating
  • Thus we have also "dark energy" which acts to drive the expansion, in opposition to gravity
  • The current theory holds that 73% of the Universe is dark energy, 23% is dark matter, and just 4% the kind of matter we know well

A key task of the telescope will be to map the distribution of dark matter, the matter that cannot be detected directly but which astronomers know to be there because of its gravitational effects on the matter we can see.

Galaxies, for example, could not hold their shape were it not for the presence of some additional "scaffolding". This is presumed to be dark matter - whatever that is.

Although this material cannot be seen directly, the telescope can plot its distribution by looking for the subtle way its mass distorts the light coming from distant galaxies. Hubble famously did this for a tiny patch on the sky - just two square degrees.

Euclid will do it across 15,000 square degrees of sky - a little over a third of the heavens.

Dark energy represents a very different problem, and is arguably one of the major outstanding issues facing 21st-Century science.

This mysterious force appears to be accelerating the expansion of the Universe. Recognition of its existence and effect in 1998 earned three scientists a Nobel Prize last year.

Euclid will investigate the phenomenon by mapping the three-dimensional distribution of galaxies.

The patterns in the great voids that exist between these objects can be used as a kind of "yardstick" to measure the expansion through time.

Again, ground-based surveys have done this for small volumes of the sky; Euclid however will measure the precise positions of some two billion galaxies out to about 10 billion light-years from Earth.

History of the Universe
  • Before 1998's Nobel Prize-winning research, it was assumed gravity was slowing the expansion
  • Now scientists say the expansion is accelerating, pushing galaxies apart at a faster and faster rate
  • Euclid's 3-D galaxy maps will trace dark energy's influence over 10 billion years of cosmic history

Euclid was selected as a "medium class" mission, meaning its cost to Esa should be close to 475m euros. The fact that member states are going 125m euros beyond this "guide price" gives an indication of just how highly this mission is regarded.

"Esa have realised this science is so compelling, they just have to do it," said Prof Bob Nichol from the University of Portsmouth, UK.

"They've got a great design and great team, and bravo to them for getting on with it. Every so often you do things that are revolutionary, and Euclid will be one of those transformational missions."

Flying Euclid will give Europe an important lead in a key area of astrophysics.

The Americans would dearly love to fly their own version of Euclid, but there is no money in the Nasa budget currently to make this happen.

The US agency was recently gifted two Hubble-class spy telescopes by the National Reconnaissance Office, but even with this donation Nasa is short of the hundreds of millions of dollars needed to turn one of them into a dark mission.

One key design difference between the US concept and Euclid would be the emphasis the American mission would place on using exploded stars, supernovas, as markers to measure the expansion rate of the Universe.

This was the approach used by the Nobel Prize winners (Saul Perlmutter and Adam Riess of the US and Brian Schmidt of Australia). It is not a technique in the primary science of Euclid, but Prof Nichol said it could be deployed at some stage.

Hubble artist's impression Hubble used the so-called "weak lensing" technique to map dark matter in a small patch of sky

"That option is still there and is still being debated," he told me.

"It could be done at the end of the main mission, if we get an extension. We could also do some supernova work during the mission. If certain parts of the sky that we want to look at are not immediately amenable, we could go look for supernovas.

"I believe we could do a fantastic supernova survey, and the Nobel Prize winners are very much involved in how to build such a programme into Euclid. They're brilliant scientists and it would be awesome to have them on board."

Major player

British scientists and engineers will play a key role in Euclid.

The UK will lead the production of the telescope's optical digital camera - one of the largest such cameras ever put in space.

The instrument will produce pictures of the sky more than 100 times larger than Hubble can. This will minimise the amount of "stitching" of images required to build Euclid's maps, making it easier to trace some of the subtle effects astronomers are trying to detect.

When its investments in the Esa portion of the budget and the visible instrument are combined, the UK's total contribution to Euclid comes out at over 100 million euros (£80m).

Jonathan Amos Article written by Jonathan Amos Jonathan Amos Science correspondent

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  • rate this

    Comment number 240.

    This is my first, and last visit to this blog.

    A science-based debate, reduced to a monologue and anonymous rating.

    Well all you raters, incapable of debate... "you did not impress!"


  • rate this

    Comment number 239.

    236 commonsense - I think most people would love a manned Mars mission, but that doesn't mean we should stop exploring other areas. The theoretical physicists that will be working on this telescope would also be hopeless at manned spaceflight but excellent at this project.
    We could land humans on Mars, but currently there is little to gain scientifically and it's still very difficult to do.

  • rate this

    Comment number 238.

    236. commonsense

    We get 70 years. During that time, we experience changes that leave us trying to keep up with it all.

    June 22, 3012 will arrive. Guaranteed.

    Can you imagine...

  • rate this

    Comment number 237.


    I'm not sure about Mars, but a moon mission would be nice. I just wonder when we'll be in a position to visit the moon again.

  • rate this

    Comment number 236.

    All this universe observation is interesting, but it would be nice if we devoted more money and resources to developing our solar system first. Like say, a Mars mission, maybe a settlement, the future is bright, but when resources are wasted on telescopes the future is further away...

  • rate this

    Comment number 235.

    234. SaintMungo

    Maybe you are right.

    I don't know.

  • rate this

    Comment number 234.

    219. Comfortably Numb
    "the possibility that the expansion of the universe is a force which gives rise to the spontaneous creation of matter from the energy of that expansion."
    Chicken/egg? Matter, dark or otherwise had to exist first before it 'expanded'.
    Perhaps ordinary matter is an equivalent of dark matter, much as energy and matter/mass are.
    Like your last two questions.

  • rate this

    Comment number 233.

    179. VesselAnaw
    "The legacy of science is not quite as rosy as the atheist fundamentalists on HYS like to portray."
    I can see where you're coming from, but it doesn't have to be that way. To change I think we have to rid ourselves of money/power crazed right wing loonies such as those in control right now.

  • rate this

    Comment number 232.

    No, Einstein didn't conjure up his famous formula out of thin air - there was a small amount of evidence, & subsequently his theory was proven (the likes of the atom bomb).

    But his theory doesn't negate the existence of time, nor does it suggest that mass can exist without a physical dimension - both impossible concepts from all we actually do know.

    That's why I am sceptical of Big Bang Theory

  • rate this

    Comment number 231.

    In 1904, Albert Einstein was a mere Swiss patent clerk... a nobody.

    12 months later, he changed physics forever - out of the blue.

    E=MC squared, and his General Theory of Relativity came out of his imagination. He conceived a reality that astounded his peers.

    He had the bottle to think outside the loop.

    When you think of a subject... don't be afraid to be different. The others don't matter.

  • rate this

    Comment number 230.

    My apologies if I have bored you... it's just one of those topics that interests me. It's an obsession in search of understanding.

    Still - the economic crisis is important... isn't it?

  • rate this

    Comment number 229.

    British Gas sees profits rise 98% in first half of year.

    Surely this is the darkest point in the Universe?

  • rate this

    Comment number 228.

    227. Stuart Wilson

    You're beginning to wonder... aren't you?

    Ignore the dot - it's surplus.

    Now you have no event - just a concept.


    That's where I'm at.

  • rate this

    Comment number 227.

    @226.Comfortably Numb
    "Take a piece of paper and make a dot. That dot is endless."

    Conceptually that dot is still an "event". That it extends and regresses infinitely could still suggest that the "event", i.e. the dot, had a "beginning" and possibly an "end", although it could indeed be infinite and not have meaningful extents in a 4-dimensional way.

  • rate this

    Comment number 226.

    225. Stuart Wilson

    At last... someone prepared to engage debate!

    It's ridiculously complicated, but I'll try to explain my perception of infinity.

    Take a piece of paper and make a dot. That dot you made represents time or space - whichever. You stand on its axis looking forward, or into the past. Larger, or smaller - stellar or quantum. That dot is endless.

    Go on... take the mental journey!

  • rate this

    Comment number 225.

    @207.Comfortably Numb
    "I believe in infinity."

    I've heard it welcomes careful drivers.

    But on a more serious note, it depends what you mean by infinity. If I travel due east for long enough, I'll end up back where I started. I could continue that travel indefinitely (lifespan notwithstanding) but still have definable boundaries, i.e. "the surface", but then I'm just two-dimensional.

  • rate this

    Comment number 224.

    The name "Big Bang" is a misnomer and was actually coined as a derogatory term. A more accurate description would be an expansion.

    Think of it as the inflation of a balloon and the expansion of the skin. To ask where the "centre" of the skin doesn't make sense and neither does asking where on the surface the expansion began.
    Of course inflate the balloon too much and you will get a big bang!

  • rate this

    Comment number 223.

    221. WiseOldBob

    Current theory - the Big Bang occurred 13.4 billion years ago. The universe is postulated to have been formed from the expansion of a single event that contained the complete mass of the universe.

    A single, central event... where was it?

    Newtonian mathematics should provide the answer - but it doesn't, because the universe is infinite.

    The centre is wherever you happen to be.

  • rate this

    Comment number 222.

    If you want to "go all scientific" now, suggest you'd be better served by a site without a 400 char limit! Try Matt Strassler's "Of Particular Significance"
    His aim is "to serve the public, including those with no background knowledge of physics". Since the site subtitle is "Conversations About Science....", I'm sure it's possible to engage on there.

  • rate this

    Comment number 221.

    219.Comfortably Numb

    "Since a Big Bang would by definition be a symmetrical event... has anyone calculated where exactly it happened?"

    Can't help with your other points but as space was created by the big bang then where it happened was litterally everywhere!

    (Having said that, I'm sure I heard a few years back that there'd been another one somewhere).


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