Feeds

Herschel and Planck off to meet Lagrange

European twin 'scope launch tomorrow

Beginner's guide to SSL certificates

The European Space Agency's Herschel and Planck space telescopes look good to go tomorrow (Thursday 14 May) at 13:12 GMT from the ESA spaceport in French Guiana.

Herschel and Planck seen in the upper stage. Pic: ESASitting atop an Ariane 5 ECA (see graphic), the two vehicles are ultimately destined for "L2", the second Lagrangian point lying around 1.5m km from Earth "where all the gravitational forces acting between two objects cancel each other out and therefore can be used by spacecraft to 'hover'".

Once "hovering", Herschel will get down to the business of probing the cosmos with its infrared telescope capable of covering the entire spectrum from far-infrared to sub-millimetre wavelengths.

Planck, meanwhile, will be set to studying the Cosmic Microwave Background "with the highest accuracy ever achieved".

That's the plan, but there's the small matter of first getting the two spacecraft onto the right trajectory using a single lifter. Once off the launchpad, the Ariane 5 ditches its solid boosters after around two-and-a-half minutes. Upper stage separation and engine ignition are scheduled for around nine minutes, after which the upper stage accelerates to towards the 10 km/s at which it will offload its cargo.

First to go will be Herschel (seen in the pic nestled at the top of the upper stage), departing at around 26 minutes after launch. One-and-a-half minutes later, the support structure which supported Herschel and protected Planck will be jettisoned and the latter will follow shortly after, at just under 29 minutes into the mission.

ESA continues: "The launcher will set the satellites directly on the path to L2. This means that no injection manoeuvre will be necessary for Herschel; the satellite will be close to its orbit around L2 right from separation. One major manoeuvre is planned to fine-tune the orbit about 24 hours after launch.

"Planck will also be in orbit around L2 at separation, but since the amplitude of its orbit is half that of Herschel, engineers will execute manoeuvres to reduce its orbit to half that of the original. The first manoeuvre is planned about 30 hours after launch."

Ultimately, and assuming all goes according to plan, Herschel's final "quasi-halo orbit" will see it at an average distance of 800,000 km from L2. Planck will settle into a Lissajous orbit "with an amplitude of 400,000 km".

For those of you who've never adopted a Lissajous or quasi-halo orbit, the former is "the natural motion of a satellite around a collinear libration point in a two-body system" (more here). The latter, ESA helpfully explains, is "an orbit that resembles a halo orbit"*, but it's actually a variant of the Lissajous orbit. ®

Bootnote

*"Where the satellite follows a simple circular or elliptical path about the libration point."

Internet Security Threat Report 2014

More from The Register

next story
GRAV WAVE DRAMA: 'Big Bang echo' may have been grit on the scanner – boffins
Exit Planet Dust on faster-than-light expansion of universe
SpaceX Dragon cargo truck flies 3D printer to ISS: Clawdown in 3, 2...
Craft berths at space station with supplies, experiments, toys
That glass of water you just drank? It was OLDER than the SUN
One MEELLION years older. Some of it anyway
Big dinosaur wowed females with its ENORMOUS HOOTER
That's right, Doris, I've got biggest snout in the prehistoric world
Japanese volcano eruption reportedly leaves 31 people presumed dead
Hopes fade of finding survivors on Mount Ontake
Relive the death of Earth over and over again in Extinction Game
Apocalypse now, and tomorrow, and the next day, and the day after that ...
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.
Beginner's guide to SSL certificates
De-mystify the technology involved and give you the information you need to make the best decision when considering your online security options.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.
Secure remote control for conventional and virtual desktops
Balancing user privacy and privileged access, in accordance with compliance frameworks and legislation. Evaluating any potential remote control choice.