Space Observatory – The Deorbited Compton Gamma Ray Observatory

An Observatory is any location set for observing or studying both terrestrial or celestial objects and happenings. Different disciplines on the Earth and outside it use an observatory for observation and analysis. These include astronomy (using Space Observatory), meteorology, geology, and volcanology, etc.

Types of Observatories

There are three types of Observatories in general.

  1. Ground-based Observatory
  2. Space Observatory
  3. Airborne Observatory

However, the one that associates with telescopes and astronomy is the Space Observatory.

What is Space Observatory?

Space-based observatories refer to any instrument such as a telescope that is located in outer space – orbiting around the Earth. The purpose of such an observatory is to study the patterns of astronomical objects in the Space that cannot enter Earth’s atmosphere. We cannot observe them with our reflective and refractive telescopes. Therefore, we need special telescopes.

In addition to this, the Space telescopes can observe celestial objects at different wavelengths of the electromagnetic region – such as ultraviolet, X rays, and gamma rays. Earth’s atmosphere does not allow us to see in these regions of the spectrum. Hence, the best is to observe them outside the atmosphere of Earth, and that’s, of course, “space.”

Moreover, since a space observatory is present above the Earth’s atmosphere, they are free from any disturbance due to atmospheric gases.

NASA’s Great Space Observatory Sent to Space

At present, NASA has been able to send four different observatories into space. They all collected various pieces of data and information. These observatories were able to give pictures of different celestial objects in different wavelengths of the spectrum. Thus, each observatory is set to study a particular wavelength.

The Space Telescopes and their Areas of Specialities

  • Compton Gamma Ray Observatory
  • Chandra X-ray Observatory
  • Hubble Space Telescope
  • Spitzer Space Telescope

Compton Gamma Ray Telescope

NASA launched it into space in 1991. This is able to detect objects at shorter wavelengths, such as Gamma Radiation in the electromagnetic spectrum

Chandra X-ray Observatory

Chandra X-ray Observatory works best in the X-ray region of the spectrum, and NASA launched it in 1999.

Hubble Space Telescope

Hubble is one of the best telescopes so far. It was launched in 1990 and detected the radiations in three regions of the electromagnetic radiation spectrum – Infrared, Ultraviolet, and Visible light.

Spitzer Space Telescope

Launching in 2003, it makes it the telescope that went into space at the end. It can observe and study the celestial objects in the more extended wavelength region of the spectrum – that is, an Infrared (IR) region.

Different Observatories to Show a Single Object

It is a technique that allows all the Great Observatories to observe the same object. In this way, the astronomers enable themselves to study the object as well as its hierarchy and methodology under different radiations. This gives them a clear insight into what is actually up in the object.

Introduction to Gamma Rays

Gamma rays mostly come from the most powerful celestial object in the universe. They have the shortest wavelength. Thus they possess the highest energy of radiations. Certain black holes, quasars, supernova, and neutron stars release or emit this powerful universe.

Importance of the Atmosphere

These radiations move across the universe, past the galaxy, and move through the stars until they finally reach Earth’s atmosphere. However, the atmosphere is so intense that it does not let the Gamma Rays spread havoc on the wall. Hence, it stops them like a substantial brick wall.

The atmosphere blocking the Gamma radiations is both a good and a bad thing. It’s good because the gamma radiations are hazardous to living things. If they enter the Earth, they will destroy nearly everything we have on our planet. The bad thing is that the astronomers cannot see past the atmosphere, presenting them with a very thick hurdle between the Earth and Space.

Compton Gamma Ray Observatory (CGRO)

CGRO launching in 1991, after the name of Arthur Holly Compton, stayed in the space for nine years. It established the fact that all the gamma bursts came from outside our galaxy. Thus, there were no sources of mysterious gamma rays within the Milky Way. It was able to discover a remnant of a supernova as well.

Telescope Type

It belongs to a Detector type telescope class whose primary purpose is to detect the presence of gamma rays in space.

Light Collecting Apparatus in the CGRO

Compton Gamma Ray Observatory’s assembly contained a Gamma-ray counter that could observe and collect the gamma rays.

Instrumentation of CGRO

The surprising thing about Compton’s Observatory is that it had no resemblance to a standard telescope. We can say this for a number of reasons, such as:

  • It did not have a Mirror as optics of a telescope.
  • It did not collect the light; instead, it tracked the gamma radiations that were otherwise difficult to observe.
  • It monitored the flashes of Visible light.

The CGRO carries a complement of four instruments that are:

  • Burst and Transient Source Experiment (BATSE)
  • Oriented Scintillation Spectrometer Experiment (OSSE)
  • Imaging Compton Telescope (COMPTEL)
  • Energetic Gamma Ray Experiment Telescope (EGRET)

Burst and Transient Source Experiment

The instrument searched for the gamma-ray radiation in the sky by carrying out detailed research. Hence, it had eight identical detectors at each of the satellite’s corners.

Oriented Scintillation Spectrometer Experiment

It detected the gamma radiations as well. However, it consisted of four different detector modules. These four detectors usually operated in pairs. One pair would observe radiations from the source, while others would take measurements from the background. These also kept switching the roles to allow for accurate measurements.

Imaging Compton Telescope

It basically determined the angle at which the photons of the electromagnetic radiation arrive. The instrument had a field of one steradian. It detected the energy of the photon with five percent.

Energetic Gamma Ray Experiment Telescope

It measured very high energy gamma radiations at a fraction of one degree and photon energy accurately within fifteen percent.

The Verdict

In December 1999, one of the gyroscopes of the observatory failed. Hence, the astronomer took the best decision and de-orbited the observatory. Although it was still operational, in the interest of public safety and to prevent an uncontrolled crash, they decided to de-orbit it by themselves before we have time.