Fairwell fair Herschel

The Hershel Observatory, an ESA telescope for which NASA helped build instruments and process data, has stopped making observations as it has finally run out of its liquid Helium coolant, as expected.  This is a good time to remember the multitude of data that a space based telescope can churn out, and the incredible scientific advancement that comes from such missions.

The Herschel Observatory

On the heels of the NASA proposed budget, it reminds us how important scientific funding and advancement are, especially for countries that have a good standard of living.  The high end technology that comes from developing missions like this often finds application in new Earth bound technologies that can drastically improve multiple fields, as well as standard of living across the globe.

The telescope, which launched four years ago, has found the universe’s ‘chilliest’ secrets by observing the frigid end of planet, star, and galaxy formation.  Hershel was able to peer into dark and cold regions of the universe that are invisible to other telescopes, showing how NASA and ESA can work cooperatively tackle unsolved mysteries in Astronomy.

Confirmation that the liquid helium ran out came on April 29th, at the beginning of the daily communication session with the spacecraft, which showed a clear rise in temperatures of all of the craft’s instruments.

In the last few weeks of observation, with the coolant running low and a shutdown of science operations impending, some of the most astounding results were released from the telescope.  Some of these (results released in April) include:

1. Sourcing Jupiter’s water content from a comet.
2. Finding a rare debris disc around an aged star.
3. Arguably its most impressive feat, finding evidence of the earliest stages of star formation in the Orion nebula.

Hershel’s instruments were designed to pick up glow from celestial objects with infrared wavelengths as long as 625 um (micrometers), 1000 times as long as we can see with our eyes.  Because heat can interfere with these devices, they were cooled to approximately 2 kelvin using liquid helium, and shielded from the sun by a large solar panel doubling as a sun shield.  The detectors were also kept cold by the craft’s orbit at the L2 Lagrange point about 1.5 million km from Earth, giving Herschel a better view of the universe by always pointing away from the sun and orbiting with the Earth.

The L2 Lagrange point, stable orbit beyond Earth

Mission highlights include: discovery of long filamentary structures in space dotted with dense star forming knots of material; detecting oxygen molecules in space among other never-before-seen molecules; discovering high speed outflows around central black holes in active galaxies; Following the water molecules from distant galaxies to the clouds of gas between stars, and eventually to planet forming systems; finding evidence that comets could have brought a substantial amount of water to Earth; And discovering a large asteroid belt around the star Vega.

Electromagnetic Spectrum, credit: ESA Herschel

It goes to show just how useful it is for an astronomer to look at the universe in all wavelengths of light, and how much we can learn from all wavelengths in the electromagnetic spectrum, not just the visible.


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