The Ariane5 lifting off from Kourou in French Guiana. Image: ESA/Arianespace.

Massive Ariane 5 To Launch Giant NextGen Telescope In Dynamic Deployment To L2

Article written: 1 Feb , 2016
Updated: 26 Apr , 2016

The Ariane 5 rocket is a workhorse for delivering satellites and other payloads into orbit, but fitting the James Webb Space Telescope (JWST) inside one is pushing the boundaries of the Ariane 5’s capabilities, and advancing our design of space observatories at the same time.

The Ariane 5 is the most modern design in the ESA’s Ariane rocket series. It’s responsible for delivering things like Rosetta, the Herschel Space Observatory, and the Planck Observatory into space. The ESA is supplying an Ariane 5 to the JWST mission, and with the planned launch date for that mission less than three years away, it’s a good time to check in with the Ariane 5 and the JWST.

The Ariane 5 has a long track record of success, often carrying multiple satellites into orbit in a single launch. Here’s its most recent launch, on January 27th from the ESA’s spaceport in French Guiana. This is Ariane 5’s 70th successful launch in a row.

But launching satellites into orbit, though still an amazing achievement, is becoming old hat for rockets. 70 successful launches in a row tells us that. The Ariane 5 can even launch multiple satellites in one mission. But launching the James Webb will be Ariane’s biggest challenge.

The thing about satellites is, they’re actually getting smaller, in many cases. But the JWST is huge, at least in terms of dimensions. The mass of the JWST—6,500 kg (14,300 lb)—is just within the limits of the Ariane 5. The real trick was designing and building the JWST so that it could fit into the cylindrical space atop an Ariane 5, and then “unfold” into its final shape after separation from the rocket. This video shows how the JWST will deploy itself.

The JWST is like a big, weird looking beetle. Its gold-coated, segmented mirror system looks like multi-faceted insect eyes. Its tennis-court sized heat shield is like an insect’s shell. Or something. Cramming all those pieces, folded up, into the nose of the Ariane 5 rocket is a real challenge.

Because the JWST will live out its 10-year (hopefully) mission at L2, rather than in orbit around Earth, it requires this huge shield to protect itself from the sun. The instruments on the James Webb have to be kept cool in order to function properly. The only way to achieve this is to have its heat shield folded up inside the rocket for launch, then unfolded later. That’s a very tricky maneuver.

But there’s more.

The heart of the James Webb is its segmented mirror system. This group of 18 gold-coated, beryllium mirrors also has to be folded up to fit into the Ariane 5, and then unfolded once it’s separated from the rocket. This is a lot trickier than launching things like the Hubble, which was deployed from the space shuttle.

Something else makes all this folding and unfolding very tricky. The Hubble, which was James Webb’s predecessor, is in orbit around Earth. That means that astronauts on Shuttle missions have been able to repair and service the Hubble. But the James Webb will be way out there at L2, so it can’t be serviced in any way. We have one chance to get it right.

Right now, the James Webb is still under construction in the “Clean Room” at NASA’s Goddard Space Flight Centre. A precision robotic arm system is carefully mounting Webb’s 18 mirrors.

A robotic arm positions one of James Webb's 18 mirrors. Image: NASA/Chris Gunn

A robotic arm positions one of James Webb’s 18 mirrors. Image: NASA/Chris Gunn

There’s still over two years until the October 2018 launch date, and there’s a lot of testing and assembly work going on until then. We’ll be paying close attention not only to see if the launch goes as planned, but also to see if the James Webb—the weird looking beetle—can successfully complete its metamorphosis.

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6 Responses

  1. Member
    Aqua4U says

    Not made for maintenance or upgrades, eh? I’ll bet eventually it gets visited when someone decides to scavenge for the beryllium and other refined metals? ARrrre there going to be Space Pirates/Scavengers in our future? L2 DOES kind of look like a good place to hide out? That is, if it isn’t already occupied… Anybody home? So the Pirates/Scavengers get there and find that the metals have already been removed… and they are being watched… and find that the hull of the ship seems to be dissolving.

    I said Space Pirates… not which Space.

  2. SteveZodiac says

    Two weeks of waiting for the worlds most expensive origami to unfold. People’s nails are going to be chewed down to their armpits

  3. Plenum says

    Very informative article, thanks!!

    Quite some time ago, I read that various man-made satellites are in orbit around L-points – SOHO around L1, for example, for many years… Article suggestion: “How Satellites Are Put into Orbit Around Lagrangian Points” What would interest me is how do we know, other than by calculations determined by gravity-cancelling effects by two masses in space, whether the satellite REALLY is at the L-point (or orbiting the L-point? Does the satellite have gravity sensors, and if so, how do those gravity sensors work? And how does the “insertion” around/to the L-point occur? (I’m thinking of somewhat the somewhat triangular, descent that Rosetta took when it gradually neared 67-P. There must have been some type of gravity-sensors on-board, right?, that Rosetta sent back to Earth so as to determine and program (from Earth) the best descent and orbital paths? (Pardon my ignorance at some of these thoughts – but it’s fun…)

  4. SteveZodiac says

    It may have inertial sensors but I think sensing the miniscule gravity of two distant objects would be too expensive. I must admit to being puzzled as to how you orbit the complete opposite of an attracting body but ESA have some good info here on how Gaia was put into L2

  5. Paul Gracey says

    One of the differences between Rosetta and an L2 point is avoiding the solid object one is trying to orbit. The other is that the mathematically predicted location relative to earth is perhaps better defined.
    L2 will probably attract probes destined for it naturally and of course it is a large area gravity well so whatever is already there apparently stands a good probability of being missed for its vastness or we would not send so expensive an object to it.

  6. Member
    Aqua4U says

    “There are 12 candidate asteroids in orbits that take them near the L1 or L2 Lagrangian points, so they would need only a small push to get them to the right spot. Changing the velocity of these objects by less than 500 meters per second would be sufficient – some would take substantially less effort. One NEO called 2006 RH120 could be captured by changing its velocity by only 58 meters per second. This could be completed as early as 2026.” –

    WERE this kind of mission to happen, L2 might get crowded? “HEY BUDDY! WATCH which direction you point your rocket exhaust!” There are several missions there already including WMAP, Planck Surveyor, Herschel and Gaia. The JWST will have some great company!

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