Tuesday, 30 December 2014

Looking to Hubble's Future and to Hubble's Successor

Artist's conception of the James Webb Space Telescope. Space Telescope Science Institute

On my recent trip to the Washington D.C. area to begin work on the history of the Hubble Space Telescope, I spent most of my time at the Goddard Space Flight Center in the Maryland suburbs of the American capital.

The control centre for Hubble is located at Goddard, and much of the development work for the space telescope was done there. Although my work is of necessity focused on Hubble's past, the engineers and scientists  at Goddard and at the Space Telescope Science Institute in Baltimore are, not surprisingly, looking to the future.

Hubble is nearing its twenty-fifth anniversary on orbit, and it has been nearly six years since the final space shuttle servicing mission upgraded its systems. Nonetheless, there is a great deal that can be done to keep Hubble operating, including changing operating procedures to minimize wear and tear on the spacecraft. The hope is to keep HST operating through the year 2020.

When Goddard staff draw up procedures designed to prolong Hubble's lifetime, they can test them on equipment that faithfully reproduces Hubble's systems. Because of Hubble's advanced age, some computer systems in these simulators resemble computers from the early days of personal computers in the 1980s.

At present, Hubble is still going strong, and with its relatively new instruments, it is delivering the best science of its career on orbit. When its systems age and force an end to its working life, a new space telescope should already be in operation.

That new instrument is the James Webb Space Telescope (JWST), which will be much larger than Hubble and operate at a much greater distance from Earth. The Webb Telescope will reside about a million miles from Earth at a point where the gravity of the Earth and the Sun balance each other out, and its mirror, which will be seven times the size of Hubble's, will operate at very low temperatures behind a gigantic sunshade.

JWST will be most sensitive to light in the infrared portion of the spectrum, which is not visible to human eyes. By concentrating on this light, the Webb Telescope will be able to peer even deeper into the history of the universe than Hubble.

The Canadian Space Agency, which was not involved in the creation of Hubble, is joining HST partners NASA and the European Space Agency in JWST. Canada is contributing a Fine Guidance Sensor that will help aim the telescope, and the Near-InfraRed Imager and Slitless Spectrograph (NIRISS), an instrument that will help Webb search for distant objects in the universe and for planets orbiting other stars. 

JWST is scheduled to be launched in 2018, and scientists hope that Hubble will still be operating at that time so that both instruments can obtain data from the same objects that can be compared, which will increase the value of the Hubble data.

The Webb Telescope is now being assembled at Goddard, and one of the highlights of my recent visit was to have a look at JWST inside its cleanroom in Building 29. Once JWST is assembled, it will undergo rigorous testing at Goddard and at the Johnson Space Center to make sure that it will be able to withstand the rigours of launch and the vacuum of space. 

JWST can be seen behind the railing along the upper centre of the photo, taken December 11 at the NASA Goddard Space Center. The silver object at left is an instrument for JWST near the end of the black booms that will hold telescope's secondary mirror. One of the golden mirror segments for the main mirror can be seen at right. Chris Gainor photo


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