At a speed of about 27,200 km per hour in an orbit 570 km above the Earth, Hubble suffered from the progressive failure of several gyroscopes – responsible for keeping the observatory steady during observations – in 1999. Left unable to perform science operations, NASA split the third servicing mission in two separate flights: SM3A and SM3B.
Upon successful completion of SM3A - marked by the replacement of Hubble’s gyroscopes - in December of 1999, the fourth servicing mission to the Hubble Space Telescope was launched on March 1, 2002.
In preparation for this mission, the 7-astronaut Columbia crew (STS-109) underwent a training period that included extensive cross training and required that all astronauts received specific training tailored to their assigned tasks.
Led by Commander Scott D. Altman, the crew flew aboard the Columbia Space Shuttle to the outer space telescope and conducted a number of extra vehicle activities to upgrade the spacecraft. The nearly 12-day mission featured five spacewalks and the installation of new science instruments.
Crucial to putting Hubble at the “apex” of its capabilities was the installation of a new scientific instrument - the Advanced Camera for Surveys (ACS) - containing advanced technology that far surpassed what had been available to the telescope to-date.
The ACS replaced the old camera and brought 10 times more discovery power thus, collecting ten times more data than the Wide Field and Planetary Camera 2 in the same span of time. With a wide field of view, high image quality and extraordinary sensitivity, Hubble’s ACS enhanced the spacecraft’s capabilities from visible to far ultraviolet. The ACS enabled to capture the most distant image of our Universe called the Hubble Deep Field, which has helped astronomers unveil the deepest and farthest mysteries of our universe.
Albeit the principal task was the installation of the ACS, several other key upgrading activities were also conducted:
- The 8-year old solar array panels were replaced with smaller rigid ones that produce 30 percent more power.
- The outdated Power Control Unit was replaced. The PCU is used to distribute electricity from the solar arrays and batteries to other parts of the telescope.
- One of the four reaction wheel assemblies that make up Hubble’s pointing control system was also exchanged.
- Another important upgrade was the installation of a new cooling system for the Near Infrared Camera and Multi-Object Spectrometer (NICMOS), which had been down since 1999 after depleting its refrigerant. With this upgrade, Hubble gained back its infrared vision.
- Astronauts fitted Hubble’s exterior with several specially coated sheets - New Outer Blanket Layers (NOBLs) - that prevent damage from sunlight and severe temperature changes and help maintain Hubble's normal operating temperature.
After numerous refurbishing and maintenance tasks during this mission, astronauts left Hubble ready to achieve its full potential and to continue revolutionizing modern astronomy by carrying out new observations and delivering unseen views of our universe.
Hubble’s latest upgrades at a glance:
Hubble was released from the Shuttle 9 March 9:32 CET.
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The clock is ticking down for the next Hubble Servicing Mission.
From the very beginning Hubble was designed to be astronaut-friendly.
Hubble berthed in the Space Shuttle bay during Servicing Mission 3A.
One of the SM3B astronauts during underwater tank training. |
