Herschel space telescope to go blind

Betelgeuse Herschel has built a huge catalogue of far-infrared and sub-mm images of the sky. This recently released image shows the layers of gas shed by Betelgeuse, one of the most familiar stars in the night sky
Cygnus-X Herschel will be remembered as the telescope that produced great vistas of gas and dust, as here in the constellation of Cygnus. Invisible to optical telescopes like Hubble, these billowing clouds and threading filaments trace the locations where future stars will form
Eagle With its far-infrared detectors, Herschel has been able to re-visit familiar objects to provide new data. This picture shows the classic “Pillars of Creation” in the Eagle Nebula, in the constellation Serpens. At long wavelengths, the clouds of gas and dust in the pillars glow, revealing processes at play in star formation
Goods survey Herschel has sought to study the evolution of galaxies. In this image taken of a small patch of sky in the constellation of Ursa Major, countless galaxies are recorded. Some of these fuzzy blobs are many billions of light-years distant
Comet One of Herschel's instruments is called HIFI. The spectrograph's job is to untangle the chemistry of space. Its study of Comet Hartley 2 showed the object to have water-ice with a similar composition to Earth's oceans
Andromeda At a relatively close distance of 2.5 million light-years, Andromeda is very similar in size to our own Milky Way Galaxy. Here, Herschel's observations (orange) are combined with the Newton XMM telescope's (blue)
RCW 120 Herschel's view of RCW 120, a bubble of gas and dust in space around a massive star. Another huge star, 8-10 times the mass of our Sun, is forming on the bubble's boundary - seen as a bright white object
Twisted ring Herschel has revealed new things about our own galaxy. Here, looking towards the centre of the Milky Way, it spies a ribbon of cold gas and dust that is more than 600 light-years across and which appears to be twisted. Scientists have yet to explain it

The European Space Agency (Esa) is about to lose the use of one of its flagship satellites.

Since 2009, the billion-euro Herschel telescope has been unravelling the complexities of star birth and galaxy evolution.

But its instruments employ special detectors that need to be chilled to fantastically low temperatures.

The helium refrigerant that does this job will run out in a few weeks and when it does, Herschel will go blind.

The coming demise of the telescope is no surprise. It is occurring just as was forecast at the start of the mission, almost to the month.

Researchers are now busy running through a final list of observations, acquiring as many images as they can in the time left available.

Already, thousands of pictures have been deposited in the Herschel archive, which is set to become a key reference source for decades into the future.

"I think there is a consensus in the community that Herschel has been a tremendous success and that we have made beautiful observations," Esa project scientist Dr Göran Pilbratt told BBC News.

The telescope was launched almost four years ago and sent to an observing position 1.5 million km from Earth.

It was equipped with a 3.5m mirror - the largest monolithic mirror ever flown - and three state-of-the-art instruments sensitive to long wavelengths of light, in the far-infrared and sub-millimetre range (55 to 672 microns).

Herschel diagram (BBC) The Herschel telescope has to be kept extremely cold to study its frigid targets

This technology has allowed Herschel to study the processes at play as large clouds of gas and dust collapse to form new stars. Its deep vision has also enabled scientists to trace the story of how galaxies have changed through cosmic time.

But the design of the instruments, and in particular of their detectors, has required Herschel be operated close to absolute zero (-273.15C).

Herschel Space Telescope

 Herschel mirror
  • Herschel is one of the largest space telescopes ever launched; its 3.5m diameter mirror perfectly captures infrared light
  • Infrared shines through gas and dust clouds that can block visible light - Herschel can see deep into dusty star-forming regions
  • The telescope is named after the astronomer William Herschel who discovered infrared radiation while studying the Sun in 1800
  • The Earth's atmosphere absorbs infrared, so Herschel was launched into space in 2009 to get a clear view of the infrared Universe

This has been achieved with the aid of a cooling system run on superfluid helium, more than 2,000 litres of which were loaded into the telescope at launch.

The cryogen has gradually boiled off during the course of the mission, and the latest calculation from engineers is that it will be gone entirely sometime in the final two weeks of this month.

Once the detectors start to warm from their ultra-frigid state, they will stop working. The end, when it happens, will be quite sudden.

Those astronomers in the queue to use Herschel at that moment will no doubt be disappointed, but also philosophical: observing time was allocated on the basis that the opportunity could not be guaranteed as the mission moved into its end phase.

Some engineering tests will be conducted on the telescope in April. The Esa operations team will then put the satellite into a slow drift around the Sun before ceasing all communications.

Prof Matt Griffin, from Cardiff University, is team leader on the Spire instrument, which is sensitive to some of the longest wavelengths. He said the telescope had exceeded all expectations.

"It will be a sad day when it makes its last observation, but the data that it has collected during its lifetime will keep astronomers busy for years," he told BBC News.

"For the next three years, the Spire team will work hard to put all Spire data into the best possible condition to be as easy as possible to access and to use in the future.

"Amongst Herschel's most exciting results have been the detection of many thousands of distant star-forming galaxies that are helping us understand how galaxies formed and evolved over cosmic time, and the mapping out in our own galaxy of the filaments and cores that are the sites of new suns being formed today."

Jonathan Amos Article written by Jonathan Amos Jonathan Amos Science correspondent

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  • rate this

    Comment number 53.

    Due to the number of people asking why the coolant couldn't be topped up, t does show a lack of understanding of how things work, & the impossibility of carrying out such a task. Have the said folks any viable recommendations as to how this may be achieved? I guess not. ALL space exploration is an absolute must - not a luxury.

  • rate this

    Comment number 52.

    An absolute triumph for the European Space Agency! Its budget its just a fraction of NASA's yet it still manages to do some really great science. Well Done Herschel!

  • rate this

    Comment number 51.

    Perhaps they'l put in on ebay - buyer to collect.

  • rate this

    Comment number 50.

    OMG, I actually learned something from comments here today:
    1. I did not know that Helium is an irreplaceable resource
    2. There are still luddites around who refuse to see the benefit to the country (and humanity) of scientific endeavour.

  • rate this

    Comment number 49.

    Such a shame such telescopes are not designed with a refuel option by sending a pod to it or similar. It will be a few years before we have a viable replacement up there.

    Its life expectancy was known but it still feels like a loss.

  • rate this

    Comment number 48.

    As for what happens next, the L2 point isn't actually completely stable, and once Herschel's thrusters are exhausted, there'd be a small chance of it returning to Earth and re-entering. Since the main cryostat is a hefty piece of kit, it might survive and impact.

    So, it will be pushed off away fromL2 into an orbit around the Sun to spend its well-earned retirement for hundreds of years at least.

  • rate this

    Comment number 47.

    "But to the layman, I for one am not convined that the outlay on a system with such a finite lifespan is pragmatic to say the least, considering the current economic climate."

    Compared to NHS IT project the Herschel 'scope was an absolute bargain. If visible spectra observations aren't practical I hope a replacement 'scope is sent as soon as possible - with updated instruments etc.

  • rate this

    Comment number 46.

    #45 I probably agree. A manned mission to mars is likely to boost technology massively (in the way that only WW2 & the Apollo could achieve) but I suspect we wouldn't learn much more about Mars than we already know. These telescopes and unmanned probes are great value for money relative to manned schemes.

  • rate this

    Comment number 45.

    Am I the only person who thinks the real advancement of human knowledge by the Hershel telescope is immeasurably more worthwhile than any manned expedition to Mars?

    Hopefully, priorities will change and successors to Hershel will get the funding they deserve. If Hershel achieved only that, it would be worth every penny.

  • rate this

    Comment number 44.

    The end-of-life of this remarkable instrument is a monumental bummer.
    Thanks Hersch. Job well done.

  • rate this

    Comment number 43.

    Well done and happy trails!

  • rate this

    Comment number 42.

    Some fantastic imaging from this telescope. Let's hope that funding can be found for a replacement a.s.a.p.
    Sir Patrick Moore would endorse the funding, even from his vantage point in the heavens! :)

  • rate this

    Comment number 41.

    Photo 4 seems to show the "foam" structure of the universe, presumably much further away than similar patterns mapped with visible light. Please tell us soon whether or not the universe IS isotropic at the largest scales. I'll bet it isn't. Why? Because I want to see the edge. So look the other way, next time, and catch it before it vanishes!

    Fantastic data! Well done!

  • rate this

    Comment number 40.

    I love astronomy and cosmology. But considering that this isn't a surprise, that we have known this was going to happen for four years, I struggle to see how it qualifies as news.

  • rate this

    Comment number 39.

    31. Desiderius Erasmus
    Presumably if we ever get that far out with humans, we could simply top it up with coolant and it would start working again - after all its not going to get damaged that far out
    Hmm. Its beyond most of the orbiting space junk but as the recent Russian meteorite demonstrated theres plenty of big rocks doing 30,000 mph out there

  • rate this

    Comment number 38.

    As previously noted, Herschel is located too far from Earth for any reasonable prospect of replenishing its helium, so it wasn't designed with that in mind.

    Why is it at L2 then? It's an ideal location for satellites that need to be cold, since it keeps both the Earth and Sun along a constant vector behind a sunshield. That's why Herschel and Planck are there, as will be Gaia and JWST.

  • rate this

    Comment number 37.

    every news story is about money these days. Go on, try to find one without a price on something. There's a challenge for you.

  • rate this

    Comment number 36.

    It should be pointed out that the planned life of this project was 3 years based on the maximum amount of coolant it was possible to launch with the telescope. The project has actually exceeded expectations and has now run for more than 3 years and 9 months. Many electronic gadgets these days don't last that long. Well done to the Herschel team.

  • rate this

    Comment number 35.

    Britain can never spend too much on science. It's what turned a small island into a major nation in the first place

  • rate this

    Comment number 34.

    If, by recharging coolant on Herschel, you're suggesting sending a craft up to it with a canister of liquid He, then you would need extremely deep pockets. Herschel does not orbit the Earth. It occupies an 800,000 km diameter lissajous orbit located at L2 (~1,500,000 km away) and just getting a craft there costs a fortune. Docking with something out there would be...challenging.


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