XMM-Newton is the biggest science satellite ever built in Europe. The collecting power of this telescope is the greatest ever launched to work at X-ray wavelengths. The total collecting mirror area is over 120 square metres spread across three individual X-ray telescopes. Its acronym stands for X-ray Multi-Mirror design and also honours Sir Isaac Newton, the English physicist and mathematician (1642-1727) who advanced theories of gravitation and optics, built the first working reflecting telescope and discovered how to split light into its components to study its spectrum.
Placed in orbit around the Earth where the atmosphere cannot block celestial X-rays, the XMM-Newton space observatory studies some of the most violent space phenomena. Since its launch in 1999, the spacecraft has helped scientists to investigate a number of mysterious cosmic phenomena, such as:
- the interaction of black holes with their surroundings;
- the explosion of supernovae and their remnants;
- the origin of the powerful gamma-ray bursts;
- the hot gas filling the space between galaxies throughout the Universe;
- the evolution of the Universe itself by looking back to its origin
Scientific highlights to date
- The discovery that the black hole in galaxy MCG-6-30-15 appears to be releasing energy as opposed to only ‘swallowing’ it. This gives support to a controversial theory proposed 25 years ago by two astronomers from Cambridge, United Kingdom.
- It has successfully probed the gravitational pull of a neutron star on the X-rays trying to escape from it.
- The proof that supernovae can cause gamma-ray bursts by detecting the tell-tale signature of an exploding star in the X-ray emission coming from the gamma-ray burst of 11 December 2001.
Since its launch, more than 1500 individual scientists (around 15% of the world’s professional astronomers) have been involved in preparing proposals for observing time on XMM-Newton.
XMM-Newton cost 689 million Euros. This included the spacecraft design and development, the launch and the ground operations during the first two years.
10 December 1999, on the first Ariane-5 commercial mission, from ESA’s Kourou Spaceport in French Guiana.
After launch, XMM-Newton was placed in a 48-hour elliptical orbit around the Earth, inclined at 40 degrees. The orbit takes it from 7 000 to 114 000 kilometres altitude. For 40 hours every orbit, the satellite is therefore outside Earth’s obscuring radiation belts.
Planned mission lifetime
The XMM-Newton spacecraft and its instrument have been designed and built to last at least 10 years. The mission has been approved to continue until end 2014.
Design: XMM-Newton is a three-axis stabilised spacecraft with a high pointing accuracy. The satellite consists of a service module bearing the X-ray mirror modules, propulsion, and electrical systems, a long telescope tube, and the focal plane assembly carrying the science instruments. The telescope consists of three barrel-shaped mirror modules, each containing 58 wafer-thin concentric mirrors, 0.3 to 0.7 metres in diameter and 0.6 metres long. These sit inside one another like Russian dolls, making up the enormous 120-square metre collecting area. X-rays slip into these assemblies and when they ‘graze’ against the mirrors, they are gently deflected to a focus.
Dimensions: Total length is 10 metres and, with its solar arrays, the satellite has a 16-metre span.
Mass: 3.8 tonnes (each X-ray mirror module has a mass of 500 kilograms).
Industrial involvement: The prime contractor was Dornier Satellitensysteme, part of Daimler Chrysler Aerospace (Friedrichshafen, Germany). They led an industrial consortium involving 46 companies from 14 European countries and one in the United States. Media Lario, Como, Italy, developed the X-ray Mirror Modules. About 1000 engineers and 150 scientists were involved in the creation of XMM-Newton.
What’s on board?
There are three EPICs, one at the focus of each of the three X-ray telescopes. They are designed to register extremely weak X-rays and detect rapid brightness variations.
Principal Investigator: Martin Turner, (X-ray Astronomy Group, University of Leicester, United Kingdom), leading a consortium of 10 institutes from four nations: the United Kingdom, Germany, Italy, and France. One of the cameras uses a new type of CCD (PN) developed by the Max Planck Institute of Extraterrestrial Physics in Garching, Germany.
EPIC also incorporates aRadiation Monitor System (ERMS)developed by the Centre d’Étude Spatiale des Rayonnements (CESR) in Toulouse, France. ERMS is a particle detector that will measure the radiation levels either from incoming solar flares or during its passage through Earth’s radiation belts. Such radiation could disturb the sensitive CCD detectors of the main science instruments.
Two Reflection Grating Spectrometers - RGSTwo of the telescopes contain structures known as gratings. These deflect about half of the incoming radiation away from the EPIC units and towards their own cameras. The gratings also ‘fan-out’ the incoming X-rays according to their energy, so that astronomers can study the presence of specific chemicals in the celestial object being observed.
Principal Investigator: Jelle Kaastra, High-Energy Astronomy Division SRON, Utrecht, The Netherlands, with Co-investigator Steven Kahn, Columbia University, NY, United States.
Optical Monitor - OMThis is a traditional, 30-centimetre aperture Richtey-Chretien telescope, aligned with the main X-ray telescope. Away from the distorting effects of Earth’s atmosphere, the telescope is as sensitive as a 4-metre ground-based telescope and allows the identification of X-ray sources with optical counterparts more easily than ever before.
Principal investigator: Keith Mason, The Mullard Space Science Laboratory, United Kingdom.
Ground control: European Space Operations Centre (ESOC) in Darmstadt, Germany), using ground stations at Perth (Australia), Kourou (French Guiana) and Santiago de Chile (Chile).
Science Operations: The ESA Vilspa Science Operations Centre in Villafranca, Spain, manages observation requests and the receipt, processing and distribution of XMM-Newton data. The XMM-Newton Survey Science Centre (SSC), University of Leicester, United Kingdom, processes, archives, and correlates all XMM observations with existing data held elsewhere in the world.
ESA Project Scientist: Norbert Schartel
ESA Mission Manager: Fred Jansen