The NASA/ESA Hubble Space Telescope has made its millionth observation since its launch in 1990. The telescope was used to search for the chemical signature of water in the atmosphere of planet HAT-P-7b, a gas giant larger than Jupiter which orbits the star HAT-P-7.

Alvaro Gimenez, head of science and robotic exploration for the European Space Agency said: “With a million observations and many thousands of scientific papers to its name, Hubble is one of the most productive scientific instruments ever built. As well as changing our view of the Universe with its stunning imagery, Hubble has revolutionised whole areas of science. Thanks to ESA’s participation in the Hubble project, the European scientific community is playing a starring role in these achievements.”

Although Hubble is perhaps best known for its detailed images of astronomical objects, the millionth observation was actually made with a spectrograph. Spectroscopy is the technique of splitting light into its component colours. The gases present in a planet’s atmosphere leave a fingerprint in the form of the distinctive colour patterns that different gases absorb. Analysing this data can give precise measurements of which elements are present in an object too distant to ever be visited by a space probe.

“We are looking for the spectral signature of water vapour. This is an extremely precise observation and it will take months of analysis before we have an answer,” explains Drake Deming of the University of Maryland and NASA’s Goddard Space Flight Center, who designed Hubble’s millionth observation. “Hubble has demonstrated that it is ideally suited for characterising the atmospheres of exoplanets and we are excited to see what this latest targeted world will reveal.”

Hubble was launched on the space shuttle Discovery in 1990. In the following 21 years, the telescope has collected over 50 terabytes of data, enough to fill more than 10 000 DVDs. The huge and varied library of data it has produced in the course of these million observations is made freely available to scientists and the public through an online archive.

European astronomers are guaranteed 15% of observing time on the telescope, but have consistently been awarded more through open competition. In the next round of Hubble observations, teams led by European scientists have been awarded more than 20% of the available time.

Hubble’s million observations include every observation of astronomical targets since its launch in addition to observations used to calibrate its suite of instruments. Hubble made the millionth observation using its Wide Field Camera 3, a visible- and infrared-light imager with an on-board spectrometer. It was installed by astronauts during the Hubble Servicing Mission 4 in May 2009.

Source: Hubblesite,