Telescopes in Space

On December 25, 2021, NASA launched the new James Webb Space Telescope, and on July 12, 2022, NASA released Webb's first images! This telescope will completely transform our understanding of the cosmos in a way no other space telescope has. To celebrate this advancement, we’ve taken the time to write about some of our favorite space telescopes currently in operation.

Ground-based telescopes operate under the protective yet challenging cloak of Earth’s atmosphere, which blocks certain wavelengths of light from observation and distorts views with turbulence. By orbiting above the Earth’s surface, space observatories have surmounted these limitations and given astronomers a truer vision of the Universe and its inspiring sights. When telescopes move beyond the limits of our atmosphere, research possibilities explode because the full electromagnetic spectrum is suddenly open for observation. There are seven types of energy wavelengths that make up this spectrum: radio, microwave, infrared, visible, ultraviolet, x-ray, and gamma ray. While all visible light and most radio waves pass through the atmosphere, x-ray and gamma ray wavelengths are completely shut out. Narrow segments of the three remaining categories — microwave, infrared, and ultraviolet — can reach Earth-based observatories, but observations in these bands are more successful when done from space.


The James Webb Space Telescope

James Webb Space Telescope

NASA’s James Webb Space Telescope will be the world’s premier space telescope. Webb’s goal is to look back into the ancient universe in a way we never have seen. Astronomers have long understood that the universe is expanding. The astronomer Vesto Slipher was the first to observe that galaxies far away from the Milky Way are generally redshifted. This is a result of the light from these moving galaxies being shifted into the infrared spectrum. Later, the astronomer Edwin Hubble observed that the motion of galaxies relative to us is directly correlated with their distance. This correlation is known as Hubble’s law, which tells us that the further we look back into space and time, the more redshifted galaxies become, to the point where they are rendered invisible to the visible spectrum.

An infrared telescope is required to be able to capture these faint, redshifted galaxies. While the James Webb Space Telescope is not the first infrared telescope to be sent into space, it is by far the largest telescope ever launched. When fully deployed, Webb will measure about 256 inches across (or 21 feet, 4 inches), significantly larger than the Hubble Space Telescope’s primary mirror. Webb will be able to observe galaxies at the very beginning of the universe and answer fundamental questions about dark energy, which drives the expansion of the universe and could unlock secrets about the origin of the universe.

Webb will be able to observe infrared light that is otherwise blocked by cosmic dust from the Milky Way and in other galaxies, as well as observe very cold and distant objects in the outer solar systems like comets. Webb will also be looking at extrasolar planets and their atmospheres, perhaps being able to identify gases that could be associated with biological life. These gases are known as “biosignatures” and if discovered would represent one of the greatest scientific discoveries in human history by finally answering the big question: Are we alone?

James Webb Space Telescope’s primary mirror vs that of the Hubble Space Telescopes. Credit: NASA

Webb will be placed at what’s called a “Lagrange” point, where the gravitational pull of the Earth is balanced out by the gravitational pull of the Sun about 1 million miles away from the Earth. This is because the Earth puts out a ton of infrared energy, making putting an infrared telescope in low-Earth orbit impractical. Webb’s main primary mirror is made up of 18 hexagonal-shaped mirror segments, each of which are about 4 feet across, enabling it to be stored in a rocket payload fairing. These mirror segments are made up of beryllium, a very light metal that is very strong in cold temperatures. After launch, the solar panels and a massive solar shade will deploy. The solar shade will enable the telescope's main mirror to be cooled to an incredibly cold temperature of -400F.


The Hubble Space Telescope

Nustar Telescope

On April 25, 1990, a whole new era of cosmic observation began with the deployment of the Hubble Space Telescope (HST) from the cargo bay of the Space Shuttle Discovery. The HST was built through a cooperative effort of the National Aeronautics and Space Agency (NASA) and the European Space Agency (ESA) and operated by the Space Telescope Science Institute (STScI).

Hubble, the first of the four space telescopes in NASA’s Great Observatories program, made its first observation on May 20, 1990. The subject was the open cluster NGC 3532 in the constellation of Carina, but operators discovered that the reflecting telescope’s 2.4-meter primary mirror had a spherical aberration that was affecting image clarity. On December 2, 1993, the first servicing mission was launched. Through a series of complex repairs by a team of astronauts, the flaw was corrected and the stunning images that Hubble is known for today began to populate.

In nearly twenty-nine years of operation, Hubble has traveled more than 3 billion miles and made more than a million observations. In addition to providing beautiful views of the cosmos, the Hubble Telescope has dramatically refined estimates of the age of the Universe, revealed the farthest galaxies ever seen, and collected scores of data on topics like exoplanets, quasars, black holes, dark energy, and dark matter.

James Webb Space Telescope

As of December 2021, Hubble is still going strong, with the occasional technical hiccup causing the telescope to enter safe mode. But regardless of the length of time the Hubble Space Telescope ultimately survives, it will go down in history as an amazing instrument that has expanded humanity’s knowledge of the solar system, the Milky Way galaxy, and the Universe itself.


Imaging X-Ray Polarimetry Explorer (IXPE)

 

IXPE was launched in December 2021 on a SpaceX Falcon 9 rocket from Kennedy Space Center into an equatorial orbit. Its goal is to observe celestial objects in the X-Ray portion of the electromagnetic spectrum. Objects that produce x-rays are usually highly energetic, such as quasars, pulsars, black holes, and much more. IXPE is designed to look at these objects in a way never seen before. Some of the objectives of IXPE include measurements of active galactic nuclei (cores of highly energetic galaxies that have an immense luminosity, such as quasars), observing magnetic fields of distant magnetars (pulsars with an incredibly powerful magnetic field), observing pulsars, and much more.


Chandra X-ray Observatory

One of NASA’s four “Great Observatories”, the Chandra X-Ray Observatory jettisoned from the bay of Space Shuttle Columbia nearly two decades ago and began an epic mission to study the hottest spots in the Universe. Named for the Nobel Prize-winning astrophysicist, Subrahmanyan Chandrasekhar, Chandra is an x-ray observatory with an orbit that reaches about one-third of the distance to the Moon — allowing for long, uninterrupted observing sessions that can last more than 50 hours. The telescope, which has a resolving power of 0.5 arc seconds, has a 10m focal length and an assembly of four nested pairs of mirrors coated with iridium and highly polished. NASA publications often emphasize the smoothness of Chandra’s mirrors by saying that “if Colorado was as smooth as Chandra’s mirrors, Pikes Peak would be less than one inch tall.”

BRITE Constellation (Bright Target Explorer)

Other science instruments on board Chandra are two transmission gratings, an advanced CCD imaging spectrometer, and a high-resolution camera. The contributions Chandra has made to the field of astrophysics are immeasurable. A few of the highlights include advancing dark matter research through its imaging of galaxy cluster collisions, providing new insight into the relationship between pulsars and nebulae through its study of the Crab Nebula, confirming the existence of a new classification of black holes —the mid-mass black hole, and monitoring the Alpha Centauri system for a decade to produce valuable data on the habitability of the closest star system to our own.


Near-Earth Object Infrared Survey Explorer (NEOWISE)

Spektr-R (RadioAstron Project)

NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission has been in orbit for nearly five years. You may recognize the name NEOWISE thanks to 2020’s Comet NEOWISE that was visible to many in the northern hemisphere. In the five years since its launch from Vandenberg Air Force Base, it has significantly added to scientists’ knowledge of asteroids and comets within our solar system. NEOWISE has also expanded our understanding of other stars and galaxies as well. Its studies are conducted by looking at infrared wavelengths, and during its time in space, NEOWISE has surpassed 95 billion recorded measurements, and it did all this while being a recycled spacecraft!

Originally, NEOWISE was known as WISE, or the Wide-field Infrared Survey Explorer, which was launched in December 2009 and dedicated to studying galaxies, stars, and solar systems by imaging the infrared light through the entire sky. In 2011, WISE was placed in hibernation after completing its primary astrophysics mission. That wasn’t the end for this successful space telescope, however. In September of 2013, WISE was reactivated and renamed NEOWISE so it could continue contributing high-quality data to IPAC at Caltech in Pasadena, California.

Since its reactivation, NEOWISE has scanned the entire sky nearly eight times and observed/characterized 29,375 objects, including 788 near-Earth objects and 136 comets. NEOWISE even detected an asteroid on April 23, 2014, whose size was estimated to be between 800 and 1,300 feet. NEOWISE has helped scientists detect countless large Near-Earth Objects that have passed by Earth and aided in detecting the size of these objects. With nearly 2.5 million infrared images of the sky collected in its four full years, NEOWISE has given much back to the studies of the Universe and shows no signs of stopping.


Gaia Space Observatory

Newton Telescope

Gaia shot forth into the sky on December 19, 2013, as part of an ambitious mission by the ESA to chart a three-dimensional map of the Milky Way Galaxy. The technology Gaia possesses will provide unprecedented positional and radial velocity measurements with accuracies needed to create a census of about one billion stars in our Galaxy; this is, by the way, only about one percent of the Galactic stellar population!

Though Gaia is still young when compared to the other space telescopes on this list, it has done much in contributing to the understanding of our Galaxy. Along with Hubble, Gaia has been able to accurately weigh the Milky Way, showing its mind-boggling weight at about 1.5 trillion solar masses within a radius of 129,000 light-years from the Galaxy’s center. This star surveyor has also spurred hundreds of scientific studies due to the data collected on the formation and evolution of stars within our Galaxy and beyond.


Solar Dynamics Observatory

Neil Gehrels Observatory

NASA’s Solar Dynamics Observatory (SDO) was launched in February 2010 with the goal to observe how the Sun creates solar activity and space weather. SDO uses three separate scientific experiments - the EUV Variability Experiment (EVE), Atmospheric Imaging Assembly (AIA), and the Helioseismic and Magnetic Imager (HM) to observe the Sun at multiple different wavelengths. The instruments that make up EVE observe the sun in ultraviolet light, observing extreme ultraviolet rays that we on Earth are protected from thanks to our atmosphere. AIA sets out to image the Sun’s corona, the outer layer of the Sun’s atmosphere visible to us only during a total solar eclipse. HMI observes the interior of the Sun to help better understand the inner mechanisms of how stars work.


Transiting Exoplanet Survey Satellite

 Chandra XRay Observatory

Launched in 2018, NASA’s Transiting Exoplanet Survey Satellite has already picked up the mantle left by the highly successful Kepler Space Telescope, which identified thousands of exoplanets in its nine-year run. TESS is seeking to dramatically expand the catalog of known exoplanets through an all-sky survey encompassing an area 400 times larger than that covered by Kepler.

Exoplanets are planets orbiting stars other than our own, and the best way to find them is by monitoring stars for temporary but regular drops in brightness that indicate a transiting body. Over the next few years, TESS will focus on monitoring the brightest 200,000 stars because the exoplanets discovered around these are more likely to yield additional information like atmospheric composition, structure, and interactions with other planets and moons. The observatory is focusing on the Southern Hemisphere for the first year and the Northern in the second year. To make its observations, TESS has four red-sensitive CCD cameras that each have a wide 24° x 24° field of view, 100mm of aperture, and excellent resolution. The spacecraft’s high Earth orbit takes 13.7 days and provides these cameras with a mostly unobstructed view.

In its first few months of operation, TESS already has found three confirmed exoplanets and identified hundreds of candidates. The first of these confirmed finds was Pi Mensae c – an exoplanet about double Earth’s size that is orbiting a star similar to our own and is about 60 light-years away. It also found a rocky planet about 49 light-years away and a planet much larger than our own that is the longest-period transiting planet within 100 light-years.

Learn More

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This Article was Last Updated on 08/14/2023