Feeds

Herschel and Planck off to meet Lagrange

European twin 'scope launch tomorrow

Securing Web Applications Made Simple and Scalable

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."

HP ProLiant Gen8: Integrated lifecycle automation

More from The Register

next story
Malaysian Airlines flight MH17 claimed lives of HIV/AIDS cure scientists
Researchers, advocates, health workers among those on shot-down plane
ALIEN BODY FOUND ON MARS: Curiosity rover snaps extraterrestrial
And NASA kept evidence to itself for over a month
Mwa-ha-ha-ha! Eccentric billionaire Musk gets his PRIVATE SPACEPORT
In the Lone Star State, perhaps appropriately enough
Diary note: Pluto's close-up is a year from … now!
New Horizons is less than a year from the dwarf planet
Forty-five years ago: FOOTPRINTS FOUND ON MOON
NASA won't be back any time soon, sadly
NASA: ALIENS and NEW EARTHS will be ours inside 20 years
ETs, habitable planets will soon pop up with our new 'scopes
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
The Essential Guide to IT Transformation
ServiceNow discusses three IT transformations that can help CIO's automate IT services to transform IT and the enterprise.
Mobile application security vulnerability report
The alarming realities regarding the sheer number of applications vulnerable to attack, and the most common and easily addressable vulnerability errors.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.