XMM-Newton (satellite)
XMM-Newton is a significant X-ray observatory satellite launched by the European Space Agency on December 10, 1999. It was the largest satellite developed by the agency and was named in honor of the renowned physicist Isaac Newton, who contributed to the field of spectroscopy. The satellite's primary mission is to detect and study X-rays from various cosmic sources, such as black holes, neutron stars, and supernova remnants. Due to Earth's atmosphere filtering out most X-rays, XMM-Newton operates in space, where it can capture high-energy X-ray emissions that provide valuable insights into the universe's structure and evolution.
The satellite features advanced instruments, including the European Photon Imaging Camera (EPIC), the Reflection Grating Spectrometer (RGS), and the Optical Monitor (OM), which work in unison to gather and analyze X-ray data. This mission has led to groundbreaking discoveries, such as direct evidence of "star cannibalism," where one star pulls gas from another, and significant findings related to supermassive black holes. The XMM-Newton has continued to function well beyond its expected lifespan, continuously enriching our understanding of complex astronomical phenomena and the underlying mechanics of the cosmos.
XMM-Newton (satellite)
FIELDS OF STUDY: Space Technology; Observational Astronomy; Aerospace Engineering
ABSTRACT: XMM-Newton, or the X-Ray Multi-Mirror Mission, was launched in 1999 by the European Space Agency (ESA). The unmanned satellite carries three x-ray telescopes and an optical monitor. X-rays produced in space do not reach Earth’s surface and can only be studied from space. The special equipment aboard XMM-Newton was designed to detect, observe, and record data needed by scientists to study x-rays and the areas of space where they are found.
Mission History
When XMM-Newton was launched from Kourou, French Guiana, on December 10, 1999, it was the largest satellite built and launched by the European Space Agency. It contained some of the most sensitive and sophisticated scientific instruments ever made. Initially the mission was known simply as XMM. It was later renamed XMM-Newton after English physicist Isaac Newton (1642–1727). Newton was the inventor of spectroscopy, which provided a way to measure the wavelengths of light and energy. The most state-of-the-art spectroscopy then available was incorporated into the XMM-Newton to facilitate its mission to detect and study x-rays.
X-rays offer specific challenges to researchers. They have small wavelengths and high energy. This makes them act more like a photon, or individual particle of light, than like a wave of light. Earth’s atmosphere filters out most x-rays before they reach the surface, and the small particles of x-rays also go through some seemingly solid surfaces. This is what allows a doctor to use x-ray technology to see dense objects like bone through soft tissue. "Seeing" x-rays in space requires both special equipment and a space-based platform beyond Earth’s atmosphere.
X-rays, when detected, reveal a great deal of information about the objects and areas of space where they originate. By collecting individual photons of x-ray light and studying how many are collected, their energy, and their speed, scientists can learn about the objects that released the x-rays. This helps scientists study such emitters as the sun, stars, neutron stars, binary stars, supernova remnants, and comets. Black holes also release x-rays by superheating the gases drawn toward their event horizons. Many of these objects are difficult or impossible to see, so detecting and studying the x-rays they produce provides valuable insight into their origin and properties. XMM-Newton established a new pinnacle in research into x-rays.
XMM-Newton Design
The XMM-Newton satellite unit is 10 meters (32.8 feet) from end to end and 16 meters (52.5 feet) across its solar panel array. A true international effort, the satellite includes parts created by forty-seven companies from fourteen European countries and the United States.
Three main parts make up XMM-Newton: the operating systems (propulsion and electrical systems), the telescope tube and assembly for the instruments, and the x-ray mirror module. During its forty-eight-hour orbit, the satellite uses three main devices and several secondary ones to gather x-ray data.
The European Photon Imaging Camera (EPIC) is aligned to the short wavelength and small particle size of x-rays. In addition to capturing images of the x-ray photons, EPIC can also reveal the time the x-ray hit the camera. Using what is known about various types of stars, supernovas, and so forth, researchers can apply data about the arrival time to deduce physical characteristics of the object that emitted the x-rays.
XMM-Newton is also equipped with the Reflection Grating Spectrometer (RGS). The RGS measures wavelengths of radiation and is enhanced with 364 mirrors each etched with 645 grooves per millimeter. The grooves disperse the x-rays at different angles and provide an alternative way to gather data on the x-rays. The Optical Monitor (OM) telescope is aligned with the main x-ray detecting telescope to provide images in the optical and ultraviolet ranges. The OM and RGS work with EPIC to capture a full range of images of a wide section of sky over time. This provides the raw data scientists need to map the section in several wavelengths, giving a full picture of the x-ray patterns emitted by the objects in that area.
Other tools aboard XXM-Newton include optical equipment for observations and a particle detector known as EPIC Radiation Monitor System (ERMS). ERMS detects and measures the radiation from Earth’s radiation belt and solar flares so that it can be factored out of the radiation data collected from space.
Satellite operations are monitored and controlled from the European Space Operations Centre (ESOC) in Darmstadt, Germany. There are also stations in French Guiana, Australia, and several other backup locations.
When XMM-Newton was launched, scientists hoped that it would remain viable in orbit for at least two years. As the satellite remained serviceable beyond that period and continued to provide groundbreaking data that changed how scientists viewed space, the mission was extended several times. XMM-Newton was still in orbit into 2022.
Discoveries from the XMM-Newton
The XMM-Newton mission has achieved a great deal of success. From its earliest days, the satellite gathered and returned data from stellar nurseries and graveyards, shedding light on how stars come into being and how they fade out and die. X-ray emissions also provide a way to spot and study objects such as distant pulsars, binary stars, and black holes.
In 2010, after eleven years of gathering data, the XMM-Newton captured something that took scientists by surprise. A neutron star is a dense, rapidly spinning star made of leftover matter from a supernova, or powerful stellar explosion. They are normally faint and nearly impossible to see. The XMM-Newton detected a large burst of light from one tiny neutron star that was part of a binary pair in Supergiant Fast X-Ray Transient IGR J18410-0535. Using data from EPIC, astronomers determined that the dense gravity of the smaller star pulled in a huge discharge of superheated gas from its companion blue giant. This created a flare that lasted four hours. Scientists had long suspected such star cannibalism events, in which one star captures a burst of gas or matter from another to fuel itself. However, the bursts are infrequent and brief, making it difficult to capture images of one from end to end. This was the first direct evidence of the phenomenon.
The x-ray studies have also produced a wealth of information about black holes, which cannot be seen but are identified by observing conditions around them. A black hole leads to the formation of x-rays when its massive gravity causes gases entering its event horizon to superheat. While other telescopes and devices can detect evidence of black holes, XMM-Newton provides much more detailed information. In 2013, researchers working with XMM-Newton discovered a black hole of three thousand or more solar masses consuming material in a small dwarf galaxy. The black hole was undetectable with conventional telescopes and appeared much smaller when viewed with the Wide-Field Infrared Survey Explorer (WISE) telescope. XMM-Newton detected x-ray emissions more than one hundred times as strong as expected from such a small galaxy. This raised new questions as to the origins and development of black holes.
In 2022, Astronomers announced that using data from XMM-Newton that they had discovered at least thirteen supermassive black holes at the center of nearby galaxies. The black holes have masses that range from thousands to billions of times greater than our sun. By observing the data, astronomers were able to determine that the amount of x-rays emitted by the black holes is more dependent on their rate of spin than their size.
Importance of XMM-Newton Research
Being able to see things in space that are otherwise invisible and undetectable provides scientists with glimpses into not only how the universe is shaped but also what it is made of and how it came to be. The extensive, detailed observations of XMM-Newton and its ability to peer into the inner workings of celestial objects and phenomena give researchers unprecedented insight into the universe.
Principal Terms
- black hole: a region of space with such strong gravitational pull that not even light can escape.
- European Photon Imaging Camera (EPIC): a camera that uses charge-couple devices (CCDs) to detect and capture images of x-rays from aboard XMM-Newton. Two metal oxide semiconductors (MOS CCDs) and a pn-CCD allow each of two EPICs to cover a large expanse of space to identify and map locations of x-ray emissions that help scientists learn about a variety of space objects and phenomena.
- European Space Agency: an intergovernmental organization made up of twenty-two European countries in charge of Europe’s space program and research since 1975.
- satellite: any small object, natural or artificial, that orbits around a larger object; one example is Earth orbiting the sun. Artificial satellites are generally deployed for research, monitoring, communication, or weather prediction purposes, and all include at least one antenna for sending and receiving data and a power source such as a battery or solar panels.
- x-ray: a form of electromagnetic radiation with short wavelengths and high energy that is produced in space by sources including supernovas, active galactic nuclei, quasars, and the superheating of gases being drawn into black holes.
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