For over 25 years, the world has marvelled at the images and insights provided by the Hubble Space Telescope. Its discoveries have literally changed our understanding of the cosmos and the origins of the Universe. In 2022, Hubble’s successor, the James Webb Space Telescope (JWST) sent back its first images and once again has humbled our knowledge and expectations of what resides in the seemingly infinite darkness of space and time. If Hubble’s legacy is anything to go by, Webb promises to unlock many more secrets during its lifetime.
These telescopes have taken the limelight for many years thanks to the utterly spectacular images that they, and their imaging team, have provided. The kaleidoscopic colours and mesmerising patterns of cosmic events offer the perfect synergy to our social media dominated age, where ‘likes’ and ‘followers’ are the new currency. But these two mirrored behemoths are not the only eyes in the sky.
Light is electromagnetic energy in the form of waves and it is the wavelength, the distance between the peaks, that dictate the type of energy produced. The electro-magnetic spectrum ranges from incredibly short wavelengths, known as gamma rays, through x-rays and ultra violet (UV) rays, before reaching the visible light that we can detect. As the wavelength increases, it moves through infra-red (IR), to microwaves and finally to radio waves.
At this moment, there are around 30 telescopes orbiting the Earth at various heights above its surface. It is unfortunate that the media-controlled world we live in dictates which of these incredible optical marvels achieves notoriety. Telescopes capture light, but light comes in various forms, not all of which create beautiful images that our primitive eyes can appreciate.
Many objects in space give off the majority of their information in these non-visible spectrums of light energy, and thus many telescopes are designed to only capture those specific wavelengths.
Here are 4 current space telescopes, in addition to Hubble and Webb, that are providing scientists and astronomers with ground-breaking data, enabling us to unravel the dark secrets of the Universe.
The Chandra X-Ray Observatory
Launched in 1999, the Chandra X-Ray Observatory orbits Earth on an eccentric plane that sees its distance from our planet range from 16 000kms to over 130 000kms, or more than a third of the distance to the Moon. Originally only planned to operate for 5 years, Chandra, like Hubble, has massively exceeded its predicted lifespan, and is still sending back information today. Its 1,2m mirror is specialised in capturing x-rays given off by incredibly hot and energetic objects.
To date, Chandra has helped astronomers see massive young stars developing inside the great Orion Nebula, discovered a new type of black hole, unravelled the chemistry of supernova remnants like the Crab Nebula in Taurus, and witnessed the catastrophic merger of galaxies.
TESS (Transiting Exoplanet Survey Satellite)
The Kepler space telescope operated from 2009 to 2018 before it was replaced by the more advanced TESS. Whereas Kepler was a general-purpose planetary finder, TESS is designed to scour the stars of our galactic neighbourhood for Earth-like exoplanets. Its sensitive camera monitors starlight for telltale peaks and dips in its brightness caused when an object passes (transits) between it and the camera. By monitoring the extent and duration of these dips, the size and orbit of these new worlds can be understood. We can then use other telescopes such as Webb to fully reveal their information and ascertain their conditions for habitable life.
During its 10 year reign, Kepler identified over 2 500 exoplanets, and to date, TESS has revealed 329, with thousands more still to be verified. It has found ‘ultra-hot’ planets that orbit their stars in a matter of days, ‘super earths’ five times larger than our own, multiple planetary systems and a Neptune-sized world orbiting two stars.
Spitzer Space Telescope
Like JWST, Spitzer was built to see in the infrared spectrum, in other words, seeing heat given off by objects that do not exhibit visible wavelengths of light. In addition to this, infrared also allows Spitzer to peer through great clouds of dust and gas, to image objects that would otherwise be obscured.
It was launched in 2003 sporting a 34 inch mirror and a liquid helium cooling system to ensure that its own body heat did not interfere with its observations (JWST achieves this by means of its tennis court sized solar shield and by being over 1 million kms from Earth). Spitzer was officially retired by NASA in 2020 but its data is still providing new and incredible insights in the depths of the Universe.
Spitzer’s accolades are many, but some of its highlights include recording the first light of an extra-solar planet and mapping the weather within its atmosphere, detecting a new ring around Saturn and in 2016, it found the most distant galaxy ever recorded at the time. Its most famous discovery occurred in 2017 when it found the Trappist-1 system: 7 earth-sized planets orbiting a single star
Gaia Space Telescope
Gaia is named after the Greek goddess of the Earth. Unlike the aforementioned telescopes, Gaia was not built to visualise the details of the cosmos, but rather to understand our position within it. Its main role is map the distance, position and motion of stars with an unprecedented precision. To date, Gaia has recorded data on over 1,7 billion objects including stars, comets, asteroids and exoplanets. Its ultimate goal is to create a 3D map of the Milky Way to better understand its origin and subsequent evolution.
Nancy Grace Roman Space Telescope
NASA’s newest astronomical observatory is scheduled to launch in early 2027 and will view the cosmos in infrared with its 2,3m diameter mirror. This is the same size as Hubble, but will be capable of far better resolution and has a vastly superior field of view, allowing much greater swathes of space to be viewed. It is named after Nancy Roman, NASA’s first chief astronomer from 1961-1963, often called the Mother of Hubble, thanks to her work in laying the foundations for Hubble’s inception.
The telescope has multiple mission goals including examining distant supernovae and exoplanets, but its primary function is to understand more about dark matter, dark energy, and the expansion of the Universe. It aims to measure the light from over a billion galaxies during its five-and-a-half year operation time.
