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I hope you are all safe and doing well.

As the news from the world oscillates from positive to negative it is often easy to forget all the brightness there is in the universe. When people visualize space, it’s often in the form of technicolor optical images of nebulae and stars. But people often overlook much of the rest of the electromagnetic spectrum when it comes to imaging space.

Indeed, several important observations and discoveries have been made in other parts of the electromagnetic spectrum. Detections of quasars, AGNs, and SMBHs have been with x-ray, pulsar detections have been done with radio, and several nebulae have been found with infrared.

In today’s post, we’ll be taking a deep dive into NASA’s primary x-ray observatory: Chandra. Chandra data has been essential for several modern astrophysics discoveries. From finding distant quasars to potentially discovering the solution to the missing baryon problem, its returns to science have been unparalleled.

But I’m getting ahead of myself! All in good time.

For now, sit back and relax. Let’s begin our exploration of this fascinating telescope!

Chandra is known as one of NASA’s “Great Observatories”. Essentially, it forms one quadrant of the four major NASA space telescopes which made observations for decades. The others, of course, are the Hubble Space Telescope, the Compton Gamma Ray Observatory, and the Spitzer Space Telescope.

 Great Observatories program - Wikipedia

Credit: NASA

Chandra specializes, as I mentioned earlier, in x-ray observation. Now, you may be familiar with x-rays in other contexts. Anyone who’s had to get braces or sprained/broken any part of their body or realistically been to a doctor’s office has had an x-ray taken of them. X-rays are useful for humans as they pass through skin easily but do not pass through bone, allowing doctors to see things underneath one’s skin.

In space, x-rays are immensely useful as there are several fascinating phenomena that generate them, and they can be used in an immense variety of contexts. 

Chandra’s story begins in the 1970s. NASA wanted to establish an x-ray telescope in an elliptical orbit around the Earth that would reach 1/3rd of the way to the moon. The distant orbit, while preventing any Earth-bound repairs from being done, would keep the telescope well clear of the Van Allen radiation belts surrounding our planet.

 This was easier said than done, however; original designs for Chandra included 4 more mirrors than were actually used, and 2 more scientific instruments. With these eliminations, the cost of the observatory finally came within NASAs budget and construction could begin.

Chandra got its name from a contest run by NASA. It is based on the noted Indian-American astrophysicist Subramaniam Chandrasekhar (you can read more about him here!) who conducted pioneering research into Type 1a Supernovae, which are incredibly bright in x-ray. The word “chandra” fittingly also means moon in Sanskrit.

On the 23rd of July, 1999 Chandra lifted off from Cape Canaveral in the body of the Space Shuttle Columbia. Being one of the heaviest loads a space shuttle had ever carried, it required complex thruster maneuvering to place it within its orbit.

 Launch of Chandra X-ray Observatory | NASA

Credit: NASA

Now, let us discuss some of the technology that drives Chandra and that makes it so phenomenal. Unlike most telescopes, Chandra uses paraboloid and hyperboloid mirrors. This is what they look like:

OSA | Transverse ray aberrations for paraboloid–hyperboloid telescopes Credit: OSA

The benefit of this is incredibly accuracy. Chandra can focus around 80%-90% of the light it captures into a focus point one arcsecond wide! This gives Chandra superior resolution to any x-ray telescope ever made. 

With this incredible quality, the returns that Chandra has given to science are incredible. Here’s a brief list of some of the phenomenal scientific developments we’ve made with Chandra:

  • Discovery of first x-ray emission from the black hole at the center of the Milky Way
  • Calculation of the currently accepted measure of the Hubble Constant based on observations
  • Discovery of the first binary brown dwarf star system
  • Visible evidence of the existence of dark matter
  • Proof of existence of the warm-hot intergalactic medium, solving the missing baryon problem

As Chandra hurtles (literally) into the future, the returns that it will give to science will continue to increase. And I hope that before we have to retire it, we will be able to make discoveries that will fundamentally change our understanding of the universe.

Clear skies!