Herschel readies itself for the Orion Nebula (w/ Video)

Jan 20, 2010
The Heterodyne Instrument for the Far Infrared (HIFI) is a high-resolution heterodyne spectrometer. It works by mixing the incoming signal with a stable monochromatic signal, generated by a local oscillator, and extracting the frequency difference for further processing in a spectrometer. HIFI will have seven separate local oscillators covering two bands from 480-1250 gigaHertz and 1410-1910 gigaHertz. HIFI was developed by a consortium led by SRON (Groningen, The Netherlands). Credits: ESA (image by C. Carreau)

(PhysOrg.com) -- ESA's Herschel observatory is back to full operation following the reactivation of its HiFi instrument. HiFi, having been offline for 160 days while engineers investigated an unexpected problem in the electronic system, is now perfectly placed to resume its study of forming stars and planets.

HIFI, the Heterodyne Instrument for the Far Infrared, was built specifically to observe water in a variety of celestial objects. Its first observation, on 22 June 2009, showed that it was performing beyond its design specification. However, by 3 August 2009, something was clearly wrong and the instrument team and ESA had to decide what to do.

Herschel is stationed 1.5 million kilometres from Earth, directly away from the Sun, and way out of the reach of astronauts. “With Herschel we can’t just go up there and fix it, we have to nurse it back to health,” says David Southwood, ESA’s Director of Science and Robotic Exploration. That nursing took 160 days of concentrated effort from an expert team of engineers.

This video is not supported by your browser at this time.
ESA’s Herschel infrared observatory will have an unprecedented view of the cold universe, bridging the gap between what can be observed from ground and earlier space missions of its kind. Infrared radiation can penetrate the clouds of gas and dust that hide astronomical objects from optical telescopes, looking deep into star-forming regions, galactic centres and planetary systems. Also cooler objects, such as tiny stars and molecular clouds, and even galaxies enshrouded in dust, which barely emit optical light, become visible in the infrared. The Orion Nebula is shown at the end of this animation. Credits: ESA (animation by C. Carreau); Orion nebula images: Hubble Space Telescope: NASA/ESA/STScI and NASA Spitzer

Firstly, the decision was made to shut down the instrument and begin a ‘forensic’ investigation to discover what had caused the problem. By December, it was apparent that an electronic component called the Local Oscillator Control Unit (LCU) had been damaged by an unexpected voltage surge, probably the result of a cosmic ray having interfered with an onboard computer.

By a piece of cosmic good fortune, HIFI’s priority targets were out of view during the investigation. This is because Herschel sees different parts of the Universe throughout the year, as it orbits the Sun. “We knew our priority targets were only coming into view from late January onwards. So the teams took a deliberate decision not to rush the rescue attempt,” says Prof. Southwood.

Secondly, once the problem had been identified, new software was written to prevent a similar event causing another voltage spike. Then the painstaking reactivation sequence was started, using Herschel’s backup LCU. Now, the instrument is fully functional once again.

“Thanks to rescheduling of targets, virtually no science data will be lost,” says Prof. Southwood. Whilst HIFI was down, mission controllers made full use of the other two instruments, PACS and SPIRE.

An unseen stellar nursery comes into view in this Herschel image. Some 700 newly-forming stars are estimated to be crowded into these colourful filaments of dust. The complex is part of a mysterious ring of stars called Gould’s Belt. Credits: ESA and the SPIRE & PACS consortia, P. André (CEA Saclay) for the Gould’s Belt Key Programme Consortia

Now it is payback time. HIFI will be used extensively during the coming months to study star forming regions in our Galaxy. In particular, the nearby Orion Nebula, a large star-forming region, will become visible towards the end of the month. HIFI was built specifically to investigate the role of water in the formation of stars and planets, and in the evolution of galaxies.

“It is great to have HIFI back, Herschel is complete once more,” says Göran Pilbratt, Project Scientist.

Explore further: Astronomers measure weight of galaxies, expansion of universe

add to favorites email to friend print save as pdf

Related Stories

Reaching the parts -- with Herschel and SPIRE

Apr 03, 2007

A UK-led instrument which will study a previously unexplored part of the Universe leaves the UK this week to be installed on the European Space Agency's Herschel spacecraft in Germany.

Herschel first images promise bright future

Jul 10, 2009

Herschel has carried out the first test observations with all its instruments, with spectacular results. Galaxies, star-forming regions and dying stars comprised the telescope's first targets. The instruments ...

Recommended for you

Evidence of a local hot bubble carved by a supernova

2 hours ago

I spent this past weekend backpacking in Rocky Mountain National Park, where although the snow-swept peaks and the dangerously close wildlife were staggering, the night sky stood in triumph. Without a fire, ...

Astronomers measure weight of galaxies, expansion of universe

10 hours ago

Astronomers at the University of British Columbia have collaborated with international researchers to calculate the precise mass of the Milky Way and Andromeda galaxies, dispelling the notion that the two galaxies have similar ...

Mysterious molecules in space

21 hours ago

Over the vast, empty reaches of interstellar space, countless small molecules tumble quietly though the cold vacuum. Forged in the fusion furnaces of ancient stars and ejected into space when those stars ...

Comet Jacques makes a 'questionable' appearance

Jul 28, 2014

What an awesome photo! Italian amateur astronomer Rolando Ligustri nailed it earlier today using a remote telescope in New Mexico and wide-field 4-inch (106 mm) refractor. Currently the brightest comet in ...

User comments : 0