Dr Chris Pearson (RAL Space), talk to Newbury AS on 23rd March 2018

Rutherford Appleton Laboratory’s Space Science department (RAL Space) has a long history. It has been involved with more than 200 instruments either flown or ground-based, covering the spectrum from radio to gamma-rays, and studies of everything from the cosmic microwave background to exoplanets. Herschel, The James Webb Space Telescope (JWST), Solar Dynamics Observatory, Solar Orbiter, Sentinel, Rosetta and Ariel all flew or will fly with RAL Space instruments. Dr Pearson’s talk covered a few of the highlights of the programme in some detail.

Herschel, launched in 2009, was ESA’s Hubble Space Telescope, and its SPIRE instrument was a RAL-built infrared camera which revealed (among many other things) star formation in the Eagle nebula, famous from the HST “pillars of creation” image. Herschel had a 3.5m primary mirror and carried 2367 litres of liquid helium coolant. It mapped the Milky Way in the IR, detecting new structures and over 15,000 galaxies before the helium ran out in 2013. The mission continued until 2016.

The JWST is now due for launch in 2020, on an ESA Ariane 5. It carries ultra-sensitive detectors for the 2-30 micron region, one being the MIRI instrument built by RAL Space, which will look for the light of the first stars to form after the Big Bang. JWST will also image and study spectra of the very first galaxies, which from Hubble data seem to be more amorphous than those we see today.

The Solar Physics group at RAL Space studies space weather and its effects on satellites, Earth’s atmosphere, communications, power systems, and potential hazards to the ISS astronauts. The Solar Orbiter mission, now being integrated at Airbus in Stevenage, has 11 instruments including one built at RAL, and is due for launch in 2020. The Earth Observation group uses a terahertz detector on the Sentinel 3 satellite to detect atmospheric constituents, ocean currents and forest fires. The group also operates the Scanning Infrared Sea Surface Temperature Radiometer (SISTER), which is installed on the liner Queen Mary 2, to gather ocean temperature data worldwide.

RAL Space built the Ptolemy instrument on the Philae lander that was part of the Rosetta mission to comet 67P. It was a chemical analysis package designed to study volatile materials from samples of the comet’s surface. In the event this was impossible, but Rosetta found that the water in 67P had a different isotope ratio from the water on Earth, raising questions about where our water originated.

The first exoplanets were discovered around pulsars in the mid-1990’s. There are now around 3700 known exoplanets, many in multiple systems, and it seems our Solar System is not typical. Many exoplanets are “hot Jupiters”: giants orbiting close to their star and losing their atmospheres. There are also “lava worlds”; high-carbon “diamond planets”; and a few “new Earths” orbiting in the so-called “Goldilocks zone” where liquid water can exist. Our closest star, Proxima Centauri, has Earth-like planets. Several new missions are planned to seek and study exoplanets, and RAL Space has been selected as engineering lead and project management for the ARIEL mission. This will study the atmospheres of exoplanets that transit their star by looking for changes in the star’s spectrum. It is a
very challenging mission requiring extreme stability in the instrumentation.

The next terrestrial challenge will be the Square Kilometre Array (SKA), intended as the world’s largest radio telescope, which in principle could detect an airport radar on a planet 10 light years away. SKA has grown into a multinational project with its headquarters at Jodrell Bank, and planned antenna sites in Australia, South Africa and China. Building, operating and synchronising thousands of antennae, and collecting, processing and storing the data will all require expertise from many fields, not just astronomy and engineering. The building of the SKA is planned to start in 2019.

Notes and summary by Chris Hooker.

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