Hubble at 25
28 April 2015 by Joanna Barstow
Hubble eXtreme Deep Field - image credit: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team
Researcher in astronomy instrumentation, Dr Sarah Kendrew, tells the story of the Hubble Space Telescope's magnificent 25 years:
25 years ago, on 24 April 1990, NASA launched the first major astrophysical observatory into space. The Hubble Space Telescope, the product of 2 decades of work in Europe and the US, marked the beginning of a new era in our study of the Universe. For the first time, we lifted a telescope out of the Earth’s churning atmosphere to avoid the twinkling and blurring effects that our planet’s protective coating has on incoming starlight. Through Hubble’s eyes, stars would be exquisitely focused, steady points of light.
The story of Hubble’s early difficulties is familiar: the blurry images, caused by a fault in the grinding of the primary mirror, the heroic servicing mission to correct the optical flaw, and finally the stunning images the science community and the whole world had been waiting for. Whilst the faulty mirror was the stuff of nightmares for the mission’s managers, engineers and for the whole scientific community, the remarkable recovery has cemented Hubble’s status as a true popular icon of science.
For the past 25 years, Hubble has remained at the forefront of astrophysical research. During 3 further manned servicing missions, astronauts replaced key components and installed new instruments, keeping the telescope competitive with and complementary to those on the ground. After Hubble, NASA and ESA went on to launch more telescopes into space - Spitzer, Chandra, WMAP, Herschel, Planck, each in their own way revolutionising our view of the Universe. But Hubble’s status as the first major space observatory and its remarkable longevity have given it A-list status amongst the world’s telescopes, and made it possibly the best known scientific facility in the world.
Beautiful images have helped to popularise astrophysics and made the telescope a household name, but Hubble is first and foremost a formidable scientific instrument. Its observations have proven critical to some of the most important discoveries of the last decades. It played a key role in the study of distant supernovae that led to the first measurements of the accelerating expansion of the Universe; leading scientists of this project were awarded the Nobel Prize for Physics in 2011. Hubble produced some of the first direct images of planets around other stars in the Milky Way Galaxy, despite the first such planet only being discovered 5 years after the telescope’s launch.
In a daring project to point Hubble at a small blank patch of sky for over 100 hours around Christmas of 1995, a team of astronomers produced the deepest ever astronomical image of the time - the Hubble Deep Field. The HDF contained thousands of galaxies in all shapes and colours, some in our local neighbourhood, others so distant their light had travelled 12 billion years to reach us. The HDF was a major boon for scientists studying the formation and evolution of galaxies over cosmic time, one of the most dynamic fields of research in astrophysics today. As Hubble’s instruments were upgraded, the Deep Fields have probed ever deeper: the most recent eXtreme Deep Field (XDF) from 2012 contains galaxies from the first half a billion years of the Universe existence, letting us quite literally look back to the dawn of time.
Today, 25 years after Hubble’s launch, the community is readying itself for the launch of Hubble’s successor, the James Webb Space Telescope, in 2018. A collaboration between the US, European and Canadian space agencies, the Webb was designed to build on Hubble’s most exciting observations: spotting the galaxies forming in the infant Universe, tracing the birth of stars and their ubiquitous planetary systems and making progress to the most challenging of goals: discovery of extra-terrestrial life in the Universe.