Spitzer Space Telescope

But of course, the ideal location for infrared astronomy is in space.

For example, the Spitzer Telescope, which was operational until 2020, and now the James Webb Space Telescope.

Like James Webb, the Spitzer Telescope had a gold-coated beryllium mirror, beryllium being preferred as it doesn't change shape in extreme cold.

Extreme cold is important because with infrared, you are trying to observe very faint heat sources, so the telescope and its detector should ideally be cooler than those faint sources.

The James Webb Space Telescope deals with that issue by having a multi-layered vacuum-gapped sun shield, in front of which are its solar panels for power and its antenna for communicating with Earth, while shadowed behind it are the telescope mirror, sub-reflector, and various cameras, detectors, and instrumentation.

The sun shield keeps everything in the cold vacuum of space at a temperature of around 34 Kelvin, which isn't bad, but for optimal infrared observations, the cameras, detectors, and instrumentation are further cooled down to seven Kelvin by slowly evaporating liquid helium.

A similar approach was adopted with the Spitzer Infrared Space Telescope, although it had a traditional telescope tube rather than a sun shield.

After its launch in 2003, Spitzer had a six-year cool mission phase, followed by a warm mission phase after its liquid helium ran out in 2009.

Hubble is the visible light telescope in NASA's Great Observatories program.

Other parts of the spectrum are covered by the Compton Gamma Ray Observatory, the Chandra X-ray Observatory- and the Spitzer Space Telescope, which covers the infrared bands.

The mid-IR to visible band successor to the Hubble Telescope is the James Webb Space Telescope, which was launched on December 25th, 2021, with the Nancy Grace Roman Space Telescope due to follow in 2026.

In 1923, Hermann Oberth, considered a father of modern rocketry, along with Robert H. Goddard and Konstantin Tsiolkovsky, published The Rocket into Planetary Space, which mentioned how a telescope could be propelled into Earth's orbit by a rocket.

No galaxy in the sample showed infrared excess, consistent with more than a small percentage of its stars being enclosed by energy harvesting structures.

At the individual star level, searches using WISE and archival data from the Spitzer Space Telescope examined hundreds of thousands of nearby stars for infrared anomalies.

The constraints now extend beyond full Dyson spheres to partial constructs.

Even a civilization that had enclosed just a fraction of its stars output, a partial Dyson swarm capturing 10 or 20% of the stellar luminosity, would produce a detectable infrared excess in these surveys.

For the overwhelming majority, almost nothing was known beyond size and orbital period.

A few dozen had crude atmospheric hints from Hubble or Spitzer.

A handful had measured masses from radial velocity follow-up.

But for most of those 5,000 worlds, the entry in the catalogue amounted to little more than a name, a radius, an orbit and a classification.

Not useless.

incomplete in a way that allowed the imagination to fill gaps that only data should fill.

Before Webb, the two most important space telescopes for exoplanet work were the Hubble Space Telescope and the Spitzer Space Telescope.

Hubble, launched in 1990, was primarily an optical and ultraviolet observatory, though it had some near-infrared capability.

Chandra mapped the X-ray remnants.

Spitzer detected the infrared glow of heated dust.

Each telescope contributed a fragment of the picture.

But none of them could see the whole thing at once.

Hubble saw the skin.

Chandra saw the heat signatures of the dead.

Spitzer caught the thermal glow of warm dust.

Each instrument captured a fragment, but none could see the full internal structure at once.

They measured distances, velocities, temperatures, building up a picture piece by piece over decades of patient observation.

NASA's Spitzer Space Telescope, launched in 2003, provided crucial data by observing in infrared light.

Infrared penetrates dust clouds more effectively than visible light, allowing astronomers to see through the murky regions that block our view.

These observations revealed the structure of our spiral arms more clearly than ever before.

They're the nurseries of the galaxy.

Then there are warm regions heated by nearby stars glowing faintly in radio and infrared wavelengths, and hot regions blasted by supernova explosions that shine in X-rays with temperatures of millions of degrees.

NASA's Spitzer Space Telescope and the European Space Agency's Herschel Space Observatory mapped these regions in detail, revealing a complex, dynamic structure constantly in motion.

But there's more to the interstellar medium than just gas and dust.