“The Hubble Space Telescope: From Cosmological Conflict to Alien Atmospheres“ with Tom Brown (Space Telescope Science Institute, Baltimore, USA)

The Hubble Space Telescope is one of the most successful scientific experiments in history. The observatory is an international project pursued as a collaboration between the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA). Launched in 1990 into low Earth orbit, Hubble was continuously improved through a series of five servicing missions, and we expect to continue science operations well into the 2020s. Hubble’s four active science instruments provide unique and powerful capabilities for imaging, spectroscopy, and astrometry at ultraviolet, optical, and near-infrared wavelengths, enabling discoveries in a wide range of science, but also extending discoveries from other facilities on the ground and in space. The ultraviolet capabilities are in particularly high demand; critical diagnostics of temperature and chemistry fall at these wavelengths and are inaccessible below the Earth’s atmosphere.

Hubble science evolves with the field. At the time of launch, there were no known exoplanets, but Hubble is currently the premier facility for characterising exoplanet atmospheres, with a significant investment of observing time each year. It has also found dusty disks and stellar nurseries throughout the Milky Way that may one day become fully fledged planetary systems.  Characterising the expansion of the universe was always a key project of the mission, but Hubble played a critical role in the discovery of the accelerating expansion associated with the mysterious dark energy permeating the universe, and recent measurements made in tandem with Gaia are creating a tension in cosmology that may be revealing new physics. Hubble demonstrates the ubiquity of black holes in the universe, provides insight into galaxy mergers and evolution over cosmic time, and probes star formation on a variety of distance scales.  Closer to home, Hubble has tracked interstellar objects as they soared through our Solar System, watched a comet collide with Jupiter, discovered moons around Pluto, and complemented other space missions dedicated to planetary science. Hubble’s focus will evolve further in the coming decade of all-sky surveys and multi-messenger astronomy. Some of Hubble’s most exciting results will be highlighted as well as expectations for the 2020s.

Hubble orbits 340 miles above Earth’s surface. This vantage point allows Hubble to observe astronomical objects and phenomena more consistently and with better detail than generally attainable from ground-based observatories. Named in honour of the trailblazing astronomer Edwin Hubble, the Hubble Space Telescope has revolutionised astronomy since its launch and deployment by the space shuttle Discovery in 1990.  Hubble has made more than 1.4 million observations over the course of its lifetime. Over 17,000 peer-reviewed science papers have been published on its discoveries. These papers have been referenced in other publications approximately 900,000 times, with the past year breaking a new yearly record of 1000 refereed papers. Every current astronomy textbook includes contributions from the observatory, and 1 in 6 astronomical research papers are influenced by Hubble. Hubble’s discoveries continue to fascinate the public, and images of the telescope, servicing missions, and science results have become cultural icons.  They appear regularly on book covers, music albums, clothing, TV shows, movies, and even ecclesiastical stained-glass windows.


Tom Brown is the Hubble Mission Head at the Space Telescope Science Institute, the Science Operations Center for the Hubble Space Telescope.  He attended the Pennsylvania State University (B.S., majors in physics and astrophysics) and the Johns Hopkins University (M.A. and Ph.D., astrophysics).  He has previously worked with the Astro-2 Space Shuttle mission, two Hubble instruments, and the James Webb Space Telescope.  His research focuses on galaxy formation and stellar evolution.  His recent research highlights include evidence that reionization quenched the star formation in nearby dwarf galaxies, and measurement of the first precise parallax for an ancient star cluster.


Seminar was recorded on November 19, 2020