How does the Hubble space telescope work?

How Does the Hubble Space Telescope Work?

The Hubble Space Telescope (HST)—you’ve probably seen its incredible images splashed across the internet and in documentaries—is more than just a pretty picture machine. It’s a real workhorse of astronomy, a joint effort between NASA and the European Space Agency (ESA). Launched way back in 1990, it’s been orbiting our planet at about 540 kilometers (340 miles) ever since, giving us a view of the cosmos that’s simply unmatched.

What makes Hubble so special? Well, unlike telescopes stuck here on Earth, Hubble floats above the atmosphere. Think of it like this: the atmosphere is like looking through a blurry window. Hubble, being above all that, gets crystal-clear views with hardly any background light mucking things up. This allows it to observe ultraviolet, visible, and near-infrared light, giving us a peek at the universe’s deepest secrets.

The Optical Magic

Hubble’s a reflecting telescope, using a Cassegrain reflector design. Sounds complicated, right? Basically, light from space hits a big primary mirror—we’re talking 2.4 meters (7 ft 10 in) across! This mirror bounces the light to a smaller, secondary mirror. That secondary mirror then focuses the light through a hole in the primary mirror, sending it on to the scientific instruments. This two-mirror setup is pretty clever because it gives sharp images across a wide area.

Hubble’s Toolbox: The Scientific Instruments

Now, let’s talk about the cool gadgets inside Hubble. It’s got a suite of scientific instruments that analyze the light it collects. The best part? These instruments can be swapped out or upgraded when astronauts visit during servicing missions. It’s like giving Hubble a software update, but with wrenches and spacesuits!

What’s on Board Right Now:

• Wide Field Camera 3 (WFC3): This is Hubble’s main camera, capturing wide-angle shots in ultraviolet, visible, and infrared light. It’s used for everything from studying how galaxies evolve to mapping dark matter.
• Cosmic Origins Spectrograph (COS): Imagine a super-sensitive light analyzer. That’s COS. It’s the most powerful ultraviolet spectrograph ever sent into space, helping us understand the structure of the “cosmic web” and how galaxies, stars, and planets form.
• Advanced Camera for Surveys (ACS): This camera is a workhorse for visible light images, but it can also see ultraviolet and near-infrared.
• Space Telescope Imaging Spectrograph (STIS): STIS is like a detective, figuring out the chemical makeup, temperature, density, and motion of objects in space. It can also take images in different types of light.
• Near Infrared Camera and Multi-Object Spectrometer (NICMOS): Designed for near-infrared imaging and spectroscopic observations. Currently inactive.
• Fine Guidance Sensors (FGS): Hubble uses three of these to stay locked onto its target. Two keep the telescope steady, while the third can be used to precisely measure the positions of stars.

The Retired Gadgets:

Hubble’s seen a few instruments come and go over the years, like the Faint Object Camera (FOC), the original Wide Field and Planetary Cameras (WFPC1 and WFPC2), and a clever device called COSTAR. COSTAR was especially important because it fixed a flaw in Hubble’s primary mirror—a case of “oops, we made a mistake,” but with a happy ending!

Powering the Dream and Keeping Control

So, how does Hubble keep the lights on? With two big solar arrays that generate about 5,000 watts of power. That’s enough to run a few houses! These arrays soak up sunlight and convert it into electricity, which is then stored in six nickel-hydrogen batteries. These batteries keep Hubble running when it’s on the night side of Earth.

Keeping Hubble pointed in the right direction is the job of the Pointing Control System. It uses sensors and gyroscopes to stay oriented. Reaction wheels help it turn, and the gyroscopes keep track of its position. And get this: Hubble zooms around Earth at about 17,000 mph, completing an orbit every 97 minutes!

Sending Data Home

Hubble sends all its amazing data back to Earth using radio waves. It bounces the signals off special satellites called Tracking and Data Relay Satellites (TDRS) that are parked in geostationary orbit. These satellites then relay the data to ground stations, which send it to the Space Telescope Science Institute (STScI) in Baltimore, Maryland. That’s where scientists process, archive, and share the data. Hubble sends data at a rate of 1 megabit per second.

Keeping Hubble Alive: Operations and Servicing

The STScI is the brains of the operation, deciding what Hubble looks at and processing all the data. The Goddard Space Flight Center (GSFC) handles the spacecraft itself. One of the coolest things about Hubble is that it was designed to be serviced in space. Astronauts have visited several times to replace instruments, fix problems, and give Hubble a general tune-up.

A Legacy of Discovery

Hubble has revolutionized our understanding of the universe. It’s helped us figure out how fast the universe is expanding, captured stunning images of distant galaxies, spotted new moons around Pluto, witnessed the birth of solar systems, and even peered at black holes. As of 2018, Hubble had made over 1.5 million observations of more than 43,500 celestial objects. And all that data has led to over 15,500 scientific papers!

Hubble is expected to keep going into the 2030s, but it now has a successor: the James Webb Space Telescope (JWST). Launched in December 2021, JWST will build on Hubble’s legacy, focusing on gathering infrared light to see even deeper into the cosmos. It’s an exciting time for astronomy, and Hubble has paved the way for a new era of discovery.