My Dark Sky

Just last Monday, on 11 May 2009, the Space Shuttle Atlantis launched with a crew of 7 to carry out the final servicing mission of our beloved Hubble Space Telescope. Hubble was already in space for more than 19 years, and with this servicing mission, we hope to extend its life at least for another 5 years.

Hubble Space Telescope was the largest and most sensitive optical-light telescope ever launched into space. While it initially suffered from a focusing problem, it was fixed three years later and since then has consistently beaming back gorgeous images and produced outstanding scientific results.

Hubble was designed in such a way that it can be periodically updated. Old cameras can be taken out and replaced with new ones. Since its launch in 1990, astronauts from NASA and ESA had visited the space observatory four times – in 1993, 1997, 1999 and 2002 – for upgrading and repair works. During this final visit – Servicing Mission 4 (SM4) which last for 11 days, astronauts will make five spacewalks to install two new instruments, repair two inactive ones and perform some component replacements.

The great peoples who are going to service a great observatory. The 7 crews of the STS-125 mission to service Hubble. Credit: NASA.

The two new instruments are the Cosmic Origins Spectrograph (COS) and the enhanced Wide Field Camera 3 (WFC3). Both instruments use advanced technology to improve Hubble’s potential for discovery dramatically and enable observations of the faint light from the youngest stars and galaxies in the Universe.

WFC3 will replace the longest operating camera on Hubble – the Wide Field and Planetary Camera 2 (WFPC2). WFC3 has a higher resolution and a larger field of view than WFPC2. This new camera will be the power behind the studies of dark energy and dark matter, the formation of individual stars and the discovery of extremely remote galaxies previously beyond Hubble’s vision.

COS will be used to study galaxy evolution, formation of planets and the rise of elements needed for life, just to mention a few. COS sees exclusively in ultraviolet light and will improve Hubble’s ultraviolet sensitivity at least 10 times, and up to 70 times when observing extremely faint objects.

Replacing instruments is complicated enough, but there are another two which need fixing – the Advanced Camera for Surveys (ACS) and the Space Telescope Imaging Spectrograph (STIS). ACS had partially stopped working in 2007 due to an electrical short and STIS suffered a power failure in 2004. Hopefully this mission will be able to resurrect these two instruments.

Apart from these cameras, there are other components that also required replacement – the batteries, gyroscopes, insulating blankets, Science Instrument Command and Data Handling Unit (SIC&DH), Hubble’s Fine Guidance Sensors that lock onto guide stars to help the telescope to point. Finally, the astronauts will install a new device called “soft capture mechanism” that will allow robotic spacecraft to attach itself to Hubble someday, to deorbit the telescope once it is at the end of its life.

STS-125 spacewalkers remove the WFPC2 from Hubble. Credit: NASA TV.

Servicing Mission 4 is now under way. Just two days ago, the space telescope has been successfully captured by space shuttle Atlantis’s robotic arm. And yesterday, astronauts John Grunsfeld and Andrew Feustel have completed the first of five spacewalks. They installed the WFC3 and a new SIC&DH unit – which contains the computer that stores, formats, and sends to Earth all the data and images Hubble collects – and also successfully attached the soft capture mechanism to Hubble.

You can follow the mission updates at Hubble Site or NASA Space Shuttle Mission Page.

~ by thChieh on May 15, 2009.

Posted in Human Space Explorations, Satellites & Spacecrafts
Tags: HST