Subscribe free to our newsletters via your
. 24/7 Space News .

Planck Reaches 0.1 K
by Staff Writers
Paris, France (SPX) Nov 24, 2008

View of the Planck flight model spacecraft after the successful completion of the thermal balance thermal vacuum (TBTV) test campaign. The TBTV tests were performed inside the the FOCAL-5 test chamber (in the background) at Centre Spatiale de Liège (CSL). The spacecraft was removed from the chamber on 20 August 2008. Copyright: ESA/Thales

The thermal balance and thermal vacuum (TBTV) test campaign for the Planck spacecraft has been completed. During this campaign the spacecraft and payload were subjected to near-flight conditions inside a thermal vacuum chamber at the Centre Spatiale de Liège (CSL) test facilities.

Over the course of about five weeks the spacecraft and payload were cooled down to operational temperatures. The extremely low operational temperature required for the HFI instrument was achieved on 22 July 2008 when the HFI bolometers reached 0.1 K

The Planck payload comprises two instruments: the High Frequency Instrument (HFI) and the Low Frequency Instrument (LFI). In order to take scientific measurements with the intended level of sensitivity, the detectors in the focal plane unit (FPU) of both instruments need to be cooled - to 20 K for the LFI and 0.1 K for the HFI.

The design of the Planck spacecraft allows for passive cooling down to 50 K through radiative heat dissipation, with the payload module and telescope shielded from the warm spacecraft components by three progressively colder V-grooves. To reach lower temperatures the spacecraft carries an active cryogenic cooling chain that is comprised of several stages:

+ A sorption cooler which lowers the temperature to 20 K for the LFI FPU and 18 K for the HFI FPU for pre-cooling

+ A Joules-Thompson cooler brings the HFI FPU down to 4 K

+ A 3He 4He dilution cooler reduces the temperature of the HFI bolometers to 0.1 K

+ An intermediate stage at 1.6 K lies within the 4 K enclosure of the HFI FPU and is used to keep different filters of the HFI instrument at 1.6 K.

TBTV test campaign at CSL
The thermal balance and thermal vacuum test campaign of the Planck flight model spacecraft has been performed inside the FOCAL-5 chamber at CSL.

One of the objectives of the TBTV test campaign was to verify that Planck's sophisticated active cryogenic cooling system achieves the correct temperatures (down to 0.1 K - a tenth of a degree above absolute zero) and that the scientific detectors demonstrate the required performance.

Shortly after the closure of the FOCAL-5 chamber on 16 June 2008 the spacecraft's active cryogenic chain was initiated to help pre-cool the different stages simultaneously.

For the test campaign the cooldown was sped up (taking place over a five week period) compared to how the spacecraft will reach its operational temperatures in space: after its launch into space Planck will gradually cool down over a period of several months during its journey to L2.

Reaching and maintaining 0.1 K
Figure 1 shows the evolution of the temperatures for the different components of the cooling system as the spacecraft was cooled from room temperature down to operational temperatures. The extremely low operational temperature of the HFI's bolometers was reached on 22 July 2008, at 19:30 UT, when the dilution cooler reached 0.1 K.

Planck's different temperature stages are each equipped with thermometers to monitor the temperature of the associated stage. For the 0.1 K stage special high sensitivity fine thermometers are used to monitor the temperature stability. These fine thermometers only work below 0.12-0.15 K.

Figure 3 shows the temperature measured by the fine thermometers within the HFI FPU for the period 22 July to 6 August 2008. The sharp spikes (both up- and down-ward) are readout noise from the measurement system and not real temperature spikes.

Following the successful completion of the TBTV test campaign the whole spacecraft was brought back to room temperature in several stages and the FOCAL-5 chamber was opened again on 19 August 2008. The Planck spacecraft was removed from the chamber the following day.

The Planck spacecraft remains at CSL where it is undergoing a series of functional tests before being prepared for shipment to the launch site early next year. These tests include an integrated satellite test, a system validation test, and a system operation validation test.

In addition the qualification model of the solar array that has been used during the TBTV test campaign will be removed and the flight model of the solar array will be integrated with the Planck spacecraft.


Related Links
Centre Spatiale de Liège (CSL)
Planck spacecraft
Understanding Time and Space

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

The Thousand-Ruby Galaxy
Paris, France (ESO) Sep 03, 2008
ESO's Wide Field Imager has captured the intricate swirls of the spiral galaxy Messier 83, a smaller look-alike of our own Milky Way. Shining with the light of billions of stars and the ruby red glow of hydrogen gas, it is a beautiful example of a barred spiral galaxy, whose shape has led to it being nicknamed the Southern Pinwheel. This dramatic image of the galaxy Messier 83 was captured ... read more

Racers Get Ready! NASA's Great Moonbuggy Registration Begins

Scientists warm to possibility of moon ice

Chandrayaan Terrain Mapping Camera Sends Pictures

Michelin Develops Lunar Wheel For NASA Moon Rover Vehicles

Solar Wind Rips Up Martian Atmosphere

Mars Express Observes Aurorae On The Red Planet

NASA Spacecraft Detects Buried Glaciers On Mars

Evidence of vast frozen water reserves on Mars: scientists

Solving The Problems Of Garbage In Space

Kazakhstan To Fund ISS Flight For Homegrown Astronaut

Kazakh Astronaut To Fly To ISS, Russian Hopeful Grounded

Space Researchers Developing Tool To Help Disoriented Pilots

Damaged Nigerian satellite can't be recovered: officials

The Chinese Space Industry Set For Take Off

China Puts Two Satellites Into Orbit

Souped-Up Rockets For Shenzhou

European to become commander of space station in 2009

Endeavour astronauts work on repairs on third spacewalk

First European To Become ISS Commander And Next European Long-Term Flight

Endeavour astronauts conduct repairs on third spacewalk

South Korea To Launch Maritime Weather Satellite Next Year

Sea Launch Partners With Intelsat On Multi-Launch Agreement

Ariane-5 With 2 satellites To Lift Off From Kourou Center December 11

HOT BIRDT 9 Starts Its Integration With Ariane 5

Beta Pictoris Planet Finally Imaged

New Planet Orbiting Dangerously Close To Giant Star

Seeing A Distant Planet

Hubble Snaps Exoplanet Orbiting Nearby Star

Eliminating Space Debris Part Two

Hollywood moguls see cinema's future in 3D

Thales To Provide The Amos-4 Ground Mission Segment To IAI

Eliminating Space Debris

The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement