Space Telescopes and Detectors

Space Telescopes

Space telescopes are a type of observational instruments placed beyond Earth’s atmosphere.
Operating from space eliminates atmospheric interference, such as weather conditions and light pollution, enabling a clearer view of celestial bodies.
They can detect electromagnetic radiation outside the visible spectrum like x-rays, ultraviolet, and infrared radiations, which are largely blocked by Earth’s atmosphere.
Famous examples include the Hubble Space Telescope and the Chandra X-ray Observatory.

Space telescopes are extremely costly to build, launch, and maintain.
Repair and upgrade missions can be complex and expensive due to their remote locations.
The lifespan of a space telescope can be limited due to factors such as: radiation damage, micrometeoroid impacts, and equipment malfunctions.

In modern astronomy, Charge-Coupled Devices (CCD) are used extensively for capturing images.
CCDs are electronic devices that convert incoming photons into electric charge and store it in tiny capacitors. This charge is then read out and converted into a digital value to create an image.
They have a very high quantum efficiency, meaning they are efficient at detecting photons, and can operate across a wide range of wavelengths from ultraviolet to near infrared.
They also have a wide dynamic range, which allows them to detect both bright and faint objects in the same scene.

The light captured by the telescopes can be analysed by a device called a spectrograph, which spreads out the light into its spectrum of different wavelengths (colours).
By examining the spectra of light from a star or galaxy, astronomers can determine its composition, temperature, velocity, and other properties.
Spectrographs can detect dips or spikes in a star’s light spectrum, which can indicate the presence of certain elements or compounds.

Astronomers often use multispectral imaging to capture data across multiple wavelengths.
Observing an object at different wavelengths can provide complementary views of it, each revealing different physical properties.
For example, an infrared image might reveal cool dust clouds in a galaxy, while an x-ray image could show hot gas in the galaxy’s core.

Radio telescopes are used to detect radio waves from space, which can provide valuable information about cosmic objects.
They typically consist of a large dish (parabolic reflector) that focuses radio waves onto a receiver.
Radio astronomy has led to important discoveries such as pulsars, quasars, and cosmic microwave background radiation.