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(Note: Adapted from Tauber et al. 2010, A&A 520, A1 and Ade et al. 2011, A&A 536)

Introduction

The performance of the Planck instruments in space is enabled by their low operating temperatures, 20 K for LFI and 0.1 K for HFI, achieved through a combination of passive radiative cooling and three active mechanical coolers. The scientific requirement for very broad frequency coverage led to two detector technologies with widely different temperature and cooling needs. Active coolers could satisfy these needs; a helium cryostat, as used by previous cryogenic space missions (IRAS, COBE, ISO, Spitzer, AKARI), could not. Radiative cooling is provided by three V-groove radiators and a large telescope baffle. The active coolers are a hydrogen sorption cooler (<20 K), a [math]^{4}[/math]He Joule-Thomson cooler (4.7 K), and a [math]^{3}[/math]He-[math]^{4}[/math]He dilution cooler (1.4 K and 0.1 K). The flight system was at ambient temperature at launch and cooled in space to operating conditions. The HFI bolometer plate reached 93 mK on 3 July 2009, 50 days after launch. The solar panel always faces the Sun, shadowing the rest of Planck, and operates at a mean temperature of 384 K. At the other end of the spacecraft, the telescope baffle operates at 42.3 K and the telescope primary mirror operates at 35.9 K. The temperatures of key parts of the instruments are stabilized by both active and passive methods. Temperature fluctuations are driven by changes in the distance from the Sun, sorption cooler cycling and fluctuations in gas-liquid flow, and fluctuations in cosmic ray flux on the dilution and bolometer plates. These fluctuations do not compromise the science data.

The contrast between the high power dissipation in the warm service module ([math]\sim[/math] 1000 W at 300 K) and that at the coldest spot in the satellite ([math]\sim[/math]100 nW at 0.1 K) are testimony to the extraordinary efficiency of the complex thermal system which has to achieve such disparate ends simultaneously while preserving a very high level of stability at the cold end. [Thomas]

(Note: Adapted from Tauber et al. 2010, A&A 520, A1 and Ade et al. 2011, A&A 536)

Introduction

The performance of the Planck instruments in space is enabled by their low operating temperatures, 20 K for LFI and 0.1 K for HFI, achieved through a combination of passive radiative cooling and three active mechanical coolers. The scientific requirement for very broad frequency coverage led to two detector technologies with widely different temperature and cooling needs. Active coolers could satisfy these needs; a helium cryostat, as used by previous cryogenic space missions (IRAS, COBE, ISO, Spitzer, AKARI), could not. Radiative cooling is provided by three V-groove radiators and a large telescope baffle. The active coolers are a hydrogen sorption cooler (<20 K), a [math]^{4}[/math]He Joule-Thomson cooler (4.7 K), and a <mat>^{3}</math>He-[math]^{4}[/math]He dilution cooler (1.4 K and 0.1 K). The flight system was at ambient temperature at launch and cooled in space to operating conditions. The HFI bolometer plate reached 93 mK on 3 July 2009, 50 days after launch. The solar panel always faces the Sun, shadowing the rest of Planck, and operates at a mean temperature of 384 K. At the other end of the spacecraft, the telescope baffle operates at 42.3 K and the telescope primary mirror operates at 35.9 K. The temperatures of key parts of the instruments are stabilized by both active and passive methods. Temperature fluctuations are driven by changes in the distance from the Sun, sorption cooler cycling and fluctuations in gas-liquid flow, and fluctuations in cosmic ray flux on the dilution and bolometer plates. These fluctuations do not compromise the science data.

The contrast between the high power dissipation in the warm service module ([math]\sim[/math] 1000 W at 300 K) and that at the coldest spot in the satellite ([math]\sim[/math]100 nW at 0.1 K) are testimony to the extraordinary efficiency of the complex thermal system which has to achieve such disparate ends simultaneously while preserving a very high level of stability at the cold end.

~Xavier

test

again

Luis was here again

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and again

this is a test

and this is another test

The contrast between the high power dissipation in the warm service module ([math]\sim[/math] 1000 W at 300 K) and that at the coldest spot in the satellite ([math]\sim[/math]100 nW at 0.1 K) are testimony to the extraordinary efficiency of the complex thermal system which has to achieve such disparate ends simultaneously while preserving a very high level of stability at the cold end. ~Xavier The performance of the Planck instruments in space is enabled by their low operating temperatures, 20 K for LFI and 0.1 K for HFI, achieved through a combination of passive radiative cooling and three active mechanical coolers. The scientific requirement for very broad frequency coverage led to two detector technologies with widely different temperature and cooling needs. Active coolers could satisfy these needs; a helium cryostat, as used by previous cryogenic space missions (IRAS, COBE, ISO, Spitzer, AKARI), could not. Radiative cooling is provided by three V-groove radiators and a large telescope baffle. The active coolers are a hydrogen sorption cooler (<20 K), a 4He Joule-Thomson cooler (4.7 K), and a 3He-4He dilution cooler (1.4 K and 0.1 K). The flight system was at ambient temperature at launch and cooled in space to operating conditions. The HFI bolometer plate reached 93 mK on 3 July 2009, 50 days after launch. The solar panel always faces the Sun, shadowing the rest of Planck, and operates at a mean temperature of 384 K. At the other end of the spacecraft, the telescope baffle operates at 42.3 K and the telescope primary mirror operates at 35.9 K. The temperatures of key parts of the instruments are stabilized by both active and passive methods. Temperature fluctuations are driven by changes in the distance from the Sun, sorption cooler cycling and fluctuations in gas-liquid flow, and fluctuations in cosmic ray flux on the dilution and bolometer plates. These fluctuations do not compromise the science data.

The contrast between the high power dissipation in the warm service module (∼ 1000 W at 300 K) and that at the coldest spot in the satellite (∼100 nW at 0.1 K) are testimony to the extraordinary efficiency of the complex thermal system which has to achieve such disparate ends simultaneously while preserving a very high level of stability at the cold end. Luis (Note: Adapted from Tauber et al. 2010, A&A 520, A1 and Ade et al. 2011, A&A 536)

Introduction

The performance of the Planck instruments in space is enabled by their low operating temperatures, 20 K for LFI and 0.1 K for HFI, achieved through a combination of passive radiative cooling and three active mechanical coolers. The scientific requirement for very broad frequency coverage led to two detector technologies with widely different temperature and cooling needs. Active coolers could satisfy these needs; a helium cryostat, as used by previous cryogenic space missions (IRAS, COBE, ISO, Spitzer, AKARI), could not. Radiative cooling is provided by three V-groove radiators and a large telescope baffle. The active coolers are a hydrogen sorption cooler (<20 K), a [math]^{4}[/math]He Joule-Thomson cooler (4.7 K), and a [math]^{3}[/math]He-[math]^{4}[/math]He dilution cooler (1.4 K and 0.1 K). The flight system was at ambient temperature at launch and cooled in space to operating conditions. The HFI bolometer plate reached 93 mK on 3 July 2009, 50 days after launch. The solar panel always faces the Sun, shadowing the rest of Planck, and operates at a mean temperature of 384 K. At the other end of the spacecraft, the telescope baffle operates at 42.3 K and the telescope primary mirror operates at 35.9 K. The temperatures of key parts of the instruments are stabilized by both active and passive methods. Temperature fluctuations are driven by changes in the distance from the Sun, sorption cooler cycling and fluctuations in gas-liquid flow, and fluctuations in cosmic ray flux on the dilution and bolometer plates. These fluctuations do not compromise the science data.

The contrast between the high power dissipation in the warm service module ([math]\sim[/math] 1000 W at 300 K) and that at the coldest spot in the satellite ([math]\sim[/math]100 nW at 0.1 K) are testimony to the extraordinary efficiency of the complex thermal system which has to achieve such disparate ends simultaneously while preserving a very high level of stability at the cold end. [Thomas]

One more time L (Note: Adapted from Tauber et al. 2010, A&A 520, A1 and Ade et al. 2011, A&A 536)

Introduction

The performance of the Planck instruments in space is enabled by their low operating temperatures, 20 K for LFI and 0.1 K for HFI, achieved through a combination of passive radiative cooling and three active mechanical coolers. The scientific requirement for very broad frequency coverage led to two detector technologies with widely different temperature and cooling needs. Active coolers could satisfy these needs; a helium cryostat, as used by previous cryogenic space missions (IRAS, COBE, ISO, Spitzer, AKARI), could not. Radiative cooling is provided by three V-groove radiators and a large telescope baffle. The active coolers are a hydrogen sorption cooler (<20 K), a [math]^{4}[/math]He Joule-Thomson cooler (4.7 K), and a [math]^{3}[/math]He-[math]^{4}[/math]He dilution cooler (1.4 K and 0.1 K). The flight system was at ambient temperature at launch and cooled in space to operating conditions. The HFI bolometer plate reached 93 mK on 3 July 2009, 50 days after launch. The solar panel always faces the Sun, shadowing the rest of Planck, and operates at a mean temperature of 384 K. At the other end of the spacecraft, the telescope baffle operates at 42.3 K and the telescope primary mirror operates at 35.9 K. The temperatures of key parts of the instruments are stabilized by both active and passive methods. Temperature fluctuations are driven by changes in the distance from the Sun, sorption cooler cycling and fluctuations in gas-liquid flow, and fluctuations in cosmic ray flux on the dilution and bolometer plates. These fluctuations do not compromise the science data.

The contrast between the high power dissipation in the warm service module ([math]\sim[/math] 1000 W at 300 K) and that at the coldest spot in the satellite ([math]\sim[/math]100 nW at 0.1 K) are testimony to the extraordinary efficiency of the complex thermal system which has to achieve such disparate ends simultaneously while preserving a very high level of stability at the cold end. [Thomas 16:35h] NOTE: Adapted from IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 50, NO. 6, DECEMBER 2003) [edit] 1 Introduction

The standard radiation environment monitor (SREM) is a particle detector developed for satellite applications. It measures high-energy electrons and protons of the space environment with a ±20∘ angular resolution, spectral information and provides the host spacecraft with radiation information. SREM was developed and manufactured by Contraves Space in cooperation with Paul Scherrer Institute under a development contract of the European Space Agency. SREM is the second generation of instruments in a programme, which was established by ESA’s European Research and Technology Centre (ESTEC) to:

   Provide minimum intrusive radiation detectors for space applications;
   Provide radiation hazard alarm function to instruments on board spacecraft;
   Assist in investigation activities related to possible radiation related anomalies observed on spacecraft;
   Assist in in-flight Technology Demonstration Activities. 

The design goals are low weight, small dimensions, low power consumption, combined with the ability to provide particle species and spectral information.

In the case of Planck, the use of the SREM was entirely within the scope of bullets 1 and 3 above as due to the nature of operations no real time alarms where possible [edit] 2 The instruments

The SREM consists of three detectors (D1, D2, and D3) in two detector heads configurations. One system is a single silicon diode detector (D3). The main entrance window is covered with 0.7 mm aluminum, which defines the lower energy threshold for electrons to ∼ 0.5 MeV and for protons to ∼ 10MeV. The other system uses two silicon diodes (detectors D1/D2) arranged in a telescope configuration. The main entrance of this detector is covered with 2 mm aluminum giving a proton and electron threshold of 20 and 1.5 MeV, respectively.A 1.7-mm-thick aluminum and 0.7–mm-thick tantalum layer separate the two diodes of the telescope configuration.

The telescope detector allows measurement of the high-energy proton fluxes with enhanced energy resolution. In addition, the shielding between the two diodes in the telescope prevents the passage of electrons. However, protons with energies greater than ∼ 30 MeVgo through. Thus, using the two diodes in coincidence gives pure proton count rates allowing subtraction of the proton contribution from the electron channels.Atotal of 15 discriminator levels are available to bin the energy of the detected events. Any two of the levels can be used to raise an alarm flag when the count rates exceed a programmable threshold. This alarm signal can then be used to control the operation of the spacecraft and its instruments. The detector electronics is capable of processing a detection rate of 100 kHz with dead-time correction below 20%. The SREM is contained in a single box of 20×12×10 and weighs 2.6 kg (see Fig. 1). The box contains the detector systems with the analog and digital front-end electronics, a power supply, and a TTC-B-01 telemetry and Telecommand interface protocol. By virtue of a modular buildup, the interface can be adapted to any spacecraft system. The power consumption is approximately 2.5 W. An essential input for the interpretation of the detection rates, in terms of particle fluxes, are the energy dependent [edit] LUis was here