OrbitalHub

The place where space exploration, science, and engineering meet

Domain is for sale. $50,000,000.00 USD. Direct any inquiries to contact@orbitalhub.com.

07-26-18

The Legacy of Planck

Posted by

 

 

ESA dixit:

“Operating between 2009 and 2013, ESA’s Planck mission scanned the sky at microwave wavelengths to observe the cosmic microwave background, or CMB, which is the most ancient light emitted in the history of our Universe. Data from Planck have revealed an “almost perfect Universe”: the standard model description of a cosmos containing ordinary matter, cold dark matter and dark energy, populated by structures that had been seeded during an early phase of inflationary expansion, is largely correct, but a few details to puzzle over remain.”

Credits Video: ESA/Planck Collaboration

 

  • Facebook
  • Google
  • Slashdot
  • Reddit
  • Live
  • TwitThis
01-10-10

Arianespace 30th Anniversary

Posted by

 

Credits: ESA/CNES/Arianespace РOptique vid̩o du CSG, L. Boyer

 

 

Arianespace was founded in 1980. With twenty-four shareholders from ten European countries (among which CNES holds 34% and EADS 30%), Arianespace is the world’s first commercial space transportation company.

 

The workhorse of Arianespace has been the Ariane launch vehicle.

 

Five versions of Ariane have served the company so far: Ariane 1, with the first successful launch on December 24, 1979, Ariane 2, launched for the first time on November 20, 1987, Ariane 3, starting its service on August 4, 1984, Ariane 4, launched on June 15, 1988, and Ariane 5, with the first successful flight on October 30, 1997.

 

 

The first launch of Ariane 5, a.k.a. Flight 501, ended with the vehicle being destroyed by its automated self-destruct system, after the high accelerations caused the inertial guidance system to crash. The crash was caused by, I quote, one of the most infamous computer bugs in history. If you like, you can take a look at the Ada code that caused the malfunction. But enough with the dark memories, this is an anniversary after all…

 

Since its inception, Arianespace has signed over 300 contracts that resulted in more than 277 satellite launches. According to Arianespace, Ariane launchers have delivered more than half of all commercial satellites now in service. The year 2009 was a very successful year for Ariane 5. The launcher orbited nine commercial satellites, the Herschel space telescope, the Planck scientific observatory, and the Helios 2B observation satellite. Ariane 5 has proven to be a versatile launch vehicle, capable of handling a wide range of missions.

 

The challenges for 2010 are many, as Arianespace is planning up to seven Ariane 5 launches. Two new launch vehicles will join Ariane 5 as part of the Arianespace family of launchers: the Vega small launcher and the Soyuz medium launcher.

 

You can read more about Arianespace, its mission, and the solutions provided to customers around the world on the Arianespace website.

 

  • Facebook
  • Google
  • Slashdot
  • Reddit
  • Live
  • TwitThis

 

Credits: ESA – D. Ducros, 2009

 

While the media has been busy with the launch of the STS-125 Atlantis for the Hubble Servicing Mission #4 from Cape Canaveral, another exciting launch is undergoing preparations further south, in Kourou, French Guiana.

 

Herschel and Planck are scheduled to launch on May 14, 2009. They will be stacked on the same Ariane 5 launch vehicle.

 

 

The two spacecraft will separate shortly after the launch (Herschel a couple of minutes before Planck) and will proceed independently to the L2 point of the Sun-Earth system. L2 is a point in space that has some special characteristics situated at 1.5 million kilometers from Earth in the opposite direction to the Sun. Herschel and Planck will operate from independent orbits around the L2 point.

 

Credits: ESA – D. Ducros, 2009

 

Stacked together, Herschel and Planck measure around 11 m in length, 4.5 m in diameter, and have a mass of approximately 5,700 kg. The piece that holds them together is called Sylda. Sylda is a support structure for Herschel and forms a protective cover for Planck.

 

The final orbit for Herschel will be a large, 900×500-thousand km, Lissajous orbit around the L2. There are three trajectory-correction maneuvers (TCM) planned for Herschel, during days L+1, L+2, and L+12. Planck will require a total of 5 TCMs that will enable it to operate from a 300×200-thousand km Lissajous orbit also around the L2 point.

 

The Lissajou orbits are inherently unstable, so both spacecraft will need regular thruster burns throughout their missions to stay on track.

 

“Without regular trajectory corrections, they would naturally drift off into a useless orbit about the Sun or Earth, with the rate of drift increasing with time,” says Gottlob Gienger, the senior flight dynamics advisor for the Herschel and Planck missions.

 

To read more about the launch of Herschel and Planck, you can visit the dedicated page on ESA’s website.

 

 

  • Facebook
  • Google
  • Slashdot
  • Reddit
  • Live
  • TwitThis

 

Credits: ESA/AOES Medialab

 

In a previous post, we presented the Planck spacecraft. We would like to dedicate this post to Planck’s big brother, Herschel. Why b(r)other? Because Planck and Herschel will be launched into space by the same Ariane 5 launcher and they will share the fairing section during the launch phase of the mission. Why big? Well, because Herschel is a larger spacecraft than Planck… actually Herschel is the largest space telescope ever built.

 

Just to have an idea about the size of the infrared telescope onboard the Herschel spacecraft, the primary mirror has a diameter of 3.5 m and a mass of only 350 kg. In comparison, the mirror of the Hubble space telescope has a diameter of 2.4 m and a mass of 1.5 tons. Obviously, a great deal of effort has been put into minimizing the mass of the telescope, an advance made possible by present-day technology.

 

 

The infrared telescope will become operational four months after its launch and will have a nominal mission lifetime of three years. The objectives that ESA set for the Herschel Space Observatory are ambitious: the study of the galaxies in the early universe, the investigation of the creation of stars, the observation of the chemical composition of the atmosphere and surfaces of comets, planets and satellites, as well as examining the molecular chemistry of the universe.

 

Like Planck, Herschel will observe the sky from the second Lagrangean Point (L2) of the Sun-Earth system. The instruments onboard Herschel will collect long-wavelength infrared radiation. Herschel will be the only space observatory to cover the spectral range from the far infrared to sub-millimeter, which is the reason why the initial name of the space observatory was Far Infrared and Sub-millimeter Telescope (FIRST).

 

Credits: ESA

 

The Herschel spacecraft will have 3.3 tons at launch, with a length of 7.5 m and a cross section of 4×4 m. The spacecraft comprises of two modules: the service module and the payload module. While the service module contains the systems for power conditioning, attitude control, data handling and communications, and the warm parts of the scientific instruments, the payload module contains the telescope, the optical bench, the cold parts of the scientific instruments and the cooling system. A sunshield protects the telescope and the cryostat from solar radiation. The sunshield also carries solar cells for power generation.

 

 

In order to make accurate observations of the infrared spectrum, parts of the scientific instruments onboard have to be cooled to temperatures close to absolute zero. Two thousand liters of liquid helium will be used for primary cooling during the mission. In addition, each detector onboard is equipped with additional cooling systems.

 

Credits: ESA/Guarniero

 

Herschel will not be the first infrared telescope launched into space. There are three predecessors that we would like to mention here: IRAS, the US-Dutch-British satellite launched in 1983, ISO – launched by ESA in 1995, and the NASA’s Spitzer Space Telescope – launched in 2003. However, these three infrared space telescopes were operated on Earth orbits. As we mentioned, Herschel will operate in the L2 point, away from any interference that would affect the scientific instruments onboard. Operating in the L2 point will also help with regard to thermal stability because the spacecraft will not move in and out of eclipse regions.

 

The launch date is set for early 2009. The journey to the final operational position will take around four months. The European Space Operations Control Center (ESOC) in Darmstadt will coordinate the mission.

 

  • Facebook
  • Google
  • Slashdot
  • Reddit
  • Live
  • TwitThis

 

Some of the most important questions asked in modern science are: how did the Universe begin, how did it evolve to its present state, and how will it continue to evolve in the future? To ask these questions, the remnant radiation that filled the Universe immediately after the Big Bang must be analyzed. This remnant radiation is known as the Cosmic Microwave Background (CMB).

 

Credits: ESA

 

ESA plans to answer these questions with Planck: the first European mission to study the birth of the Universe. The Planck Mission will collect CMB radiation measurements using highly sensitive sensors that are operating at very low temperatures. The measurements will be used to map the smallest variations of the CMB detected to date.

 

The Planck spacecraft will weigh around 1,900 kg at launch. It is 4.2 m high and has a maximum diameter of 4.2 m. There are two modules that comprise the spacecraft: a service module and the payload module.

 

The service module contains the systems for power generation, attitude control, data handling and communication, and the warm components of the scientific payload. The payload module contains the telescope, the optical bench, the detectors, and the cooling system (which is of critical importance, as we shall see).

 

The telescope is an important onboard component. The Planck telescope is a Gregorian telescope with an off-axis parabolic primary mirror 1.75 x 1.5 meters in size. A secondary mirror focuses the incoming microwave radiation on two sets of highly sensitive detectors: the Low Frequency Instrument (LFI) and the High Frequency Instrument (HFI). The Gregorian design offers two key advantages: it is compact and it does not block the optical path.

 

Credits: ESA/Thales

 

The LFI will be operating at –253 degrees Celsius. The array of twenty-two tuned radio receivers that comprise LFI will produce high-sensitivity, multi-frequency measurements of the microwave sky in the frequency range of 27 GHz to 77 GHz.

 

The HFI has to be cooled to –272.9 degrees Celsius in order to operate (one tenth of one degree above the absolute zero!). HFI’s fifty-two bolometric detectors will produce high-sensitivity, multi-frequency measurements of the diffuse sky radiation in the frequency range of 84 GHz to 1 THz.

 

A baffle surrounds the telescope and instruments. The baffle prevents light from the Sun and the Moon from altering the measurements. A complex system of refrigerators is used onboard the spacecraft in order to achieve the temperatures needed for nominal operation. The detectors have to work at temperatures close to the absolute zero, otherwise their own emissions can alter the measurements.

 

The two instruments will be used to measure the small variations of the CMB across the sky. By combining the measurements, a full sky map of unprecedented precision will be produced. The map will help astronomers decide which theories on the birth and the evolution of the Universe are correct. Questions like ‘what is the age of the Universe?’ or ‘what is the nature of the dark-matter?’ will be answered.

 

The mission was initially designed as COBRAS/SAMBA (Cosmic Background Radiation Anisotropy Satellite and Satellite for Measurement of Background Anisotropies) because it grew out of two mission proposals that had similar objectives. When the mission was approved in 1996, it was also renamed as Planck in honor of the German scientist Max Planck (1858 – 1947). Max Planck was awarded the Nobel Prize for Physics in 1918.

 

Credits: ESA

 

The mission is a collaborative effort. The Planck spacecraft was designed and built by a consortium led by Alcatel Alenia Space (Cannes, France). The telescope mirrors are manufactured by EADS Astrium (Friedrichshafen, Germany). The Low Frequency Instrument (LFI) was designed and built by a consortium led by the Instituto di Astrofisica Spaziale e Fisica Cosmica (IASF) in Bologna, Italy. The High Frequency Instrument (HFI) was designed and built by a consortium led by the Institut d’Astrophysique Spatiale (CNRS) in Orsay, France.

 

The Planck Mission has two predecessors: the Cosmic Background Explorer (COBE) and the Wilkinson Microwave Anisotropy Probe (WMAP).

 

Credits: ESA

 

The Planck spacecraft will be launched in early 2009 from Kourou, French Guiana. An Ariane 5 booster will place the spacecraft in a trajectory towards the L2 point. The L2 point stands for Second Lagrangian Point and it is located around 1.5 million kilometers away from Earth in a direction diametrically opposite the Sun. It will be a dual launch configuration, as the Herschel spacecraft will be launched together with Planck.

 

Between four to six months after the launch, Planck will reach its final position. It will take six more months before Planck will be declared operational.

 

Planck will perform scientific measurements for fifteen months, allowing two complete sky surveys. The spacecraft will be operational as along as there are resources for the cooling systems onboard.

 

For more details on the ESA’s Planck Mission you can visit the mission’s home page on the ESA website.

 

  • Facebook
  • Google
  • Slashdot
  • Reddit
  • Live
  • TwitThis