Importance Score: 45 / 100 🔵
The Hubble Space Telescope stands as a remarkable achievement of engineering and human creativity. Comparable in size and mass to a large school bus, Hubble’s contributions to the realms of science and astronomy are vast. This article explores the Hubble Space Telescope’s deployment, servicing missions, and continued operation, highlighting its pivotal role in expanding our cosmic understanding.
Hubble Space Telescope: A Legacy of Discovery
Beyond capturing stunning, otherworldly images, Hubble embodies human inquisitiveness and resolve. Functioning for over three decades, with five servicing missions, it has transmitted nearly 250 terabytes of data, significantly enriching our comprehension of the cosmos.
The concept for a large, orbiting space telescope emerged in the late 1960s. However, securing funding from the U.S. Congress required almost ten years of advocacy and meticulous planning. It then took another five years to officially name the telescope after the distinguished American astronomer Edwin Hubble. The Challenger disaster in January 1986 further delayed Hubble’s launch, adding another five-year wait before it finally reached orbit.
Deployment of the Hubble Telescope
The STS-31 crew members included:
- Loren J. Shriver, Commander
- Charles F. Bolden, Pilot
- Steven A. Hawley, Mission Specialist
- Bruce McCandless, Mission Specialist
- Kathryn D. Sullivan, Mission Specialist
Hubble was equipped with several instruments, including the Wide Field Planetary Camera (WFPC), the Goddard High Resolution Spectrograph (GHRS), the Faint Object Camera (FOC), the Faint Object Spectrograph (FOS), and the High-Speed Photometer (HSP).
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Launched on April 24, 1990, Hubble was housed in the cargo bay of the Space Shuttle Discovery. STS-31 marked Discovery’s tenth launch and the 35th space shuttle mission.
One day post-orbit insertion (April 25), the STS-31 crew deployed Hubble and dedicated subsequent days to activating the telescope. Discovery returned to Earth on April 29, positioning Hubble at an altitude of 380 miles (612 kilometers) to unveil the universe’s mysteries.
However, the initial images transmitted back were blurred, a significant setback for the $1.5 billion telescope three decades in the making.
In June 1990, NASA announced a spherical aberration in Hubble’s primary mirror, caused by a minuscule 2-micron error in curvature—approximately 1/50th the width of a human hair. This flaw rendered the telescope largely ineffective. Fortunately, Hubble’s design allowed for servicing, prompting NASA to devise a solution.
Servicing Mission 1: Correcting Hubble’s Vision
The STS-61 crew comprised:
- Richard Covey, Mission Commander
- Kenneth Bowersox, Pilot
- Kathryn Thornton, Mission Specialist
- F. Story Musgrave, Mission Specialist
- Claude Nicollier, Mission Specialist
Hubble’s design incorporated handrails for astronaut maintenance and modular components for technological upgrades. This foresight enabled NASA to rectify Hubble’s initial issues.
During Servicing Mission 1 (SM1), the STS-61 astronauts aboard Endeavor spent over 35 hours across five spacewalks to implement upgrades. They installed the Corrective Optics Space Telescope Axial Replacement (COSTAR) unit, effectively providing Hubble with “glasses.” Additionally, the WFPC was replaced with WFPC2, featuring internal corrective optics. The mission also upgraded Hubble’s solar arrays and gyroscopes for enhanced tracking.
SM1 restored Hubble’s operational capabilities and yielded some of its most memorable images.
Servicing Mission 2: Enhancing Performance
The STS-82 crew included:
- Kenneth Bowersox, Mission Commander
- Scott Horowitz, Pilot
- Joseph Tanner, Mission Specialist
- Steven Hawley, Mission Specialist
- Gregory Harbaugh, Mission Specialist
- Mark Lee, Mission Specialist
- Steven Smith, Mission Specialist
Servicing Mission 2 (SM2) focused on upgrades to boost performance.
Launched on STS-82 in February 1997, Discovery delivered two new instruments: the Space Telescope Imaging Spectrograph (STIS) and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS), replacing the GHRS and FOS. This broadened Hubble’s vision into near-infrared wavelengths. The mission also replaced degraded data recorders and other hardware.
Servicing Mission 3A: Emergency Repairs
The STS-103 crew consisted of:
- Curtis Brown, Mission Commander
- Scott Kelly, Pilot
- Jean-Francois Clervoy, Mission Specialist
- Michael Foale, Mission Specialist
- John Grunsfeld, Mission Specialist
- Steven Smith, Mission Specialist
- Claude Nicollier, Mission Specialist
Originally slated for June 2000, Servicing Mission 3 (SM3) was divided into two missions. An emergency SM3A was scheduled for Space Shuttle Discovery, designated STS-102 in December 1999.
Many spacewalks surpassed eight hours, ranking among the longest in shuttle history. Astronauts Steven Smith and John Grunsfeld replaced all six gyroscopes and installed a new transmitter and data recorder.
Michael Foale and Claude Nicollier replaced Hubble’s main computer, increasing its processing speed nearly 20-fold, and upgraded the fine guidance sensors.
Servicing Mission 3B: Enhancing Imaging Capabilities
The STS-109 crew members were:
- Scott Altman, Mission Commander
- Duane Carey, Pilot
- John Grunsfeld, Payload Commander and Mission Specialist
- Nancy Currie, Mission Specialist
- Richard Linnehan, Mission Specialist
- James Newman, Mission Specialist
- Michael Massimino, Mission Specialist
Hubble’s Advanced Camera for Surveys (ACS) replaced the aging FOC, boosting imaging power tenfold. Astronauts also replaced Hubble’s solar arrays, worn by radiation and debris.
The new solar arrays provided 20% to 30% more power. The Power Control Unit (PCU) was replaced, and a new cooling system extended the lifespan of NICMOS.
Servicing Mission 4: The Final Visit
The STS-125 crew included:
- Scott Altman, Mission Commander
- Gregory Johnson, Pilot
- Michael Good, Mission Specialist
- Megan McArthur, Mission Specialist
- Andrew Feustel, Mission Specialist
- Michael Massimino, Mission Specialist
- John Grunsfeld, Mission Specialist
Space Shuttle Atlantis launched on May 11, 2009, carrying the Cosmic Origins Spectrograph (COS) and Wide Field Camera 3 (WFC3).
With the FOC replaced during SM3B, the COSTAR instrument was no longer needed. COS replaced COSTAR and complemented STIS, bridging the ultraviolet spectrum detection with optical to near-infrared light. The astronauts also repaired STIS, inoperable since August 2004 due to a power supply failure.
The ACS contributed to iconic images like the Hubble Ultra Deep Field but suffered an electrical failure in 2007. Repair tasks for STIS and ACS were similar, but the maintenance locations differed significantly from expectations.
NASA astronauts trained for two years to develop the necessary tools and techniques for this final repair mission.
Hubble’s Continued Operation of the Space Telescope
In the years since the last servicing mission, the Hubble Space Telescope has continued to deliver remarkable cosmic views, albeit with operational challenges. NASA has implemented tighter operating constraints to sustain functionality despite ongoing issues.
As gyros failed, technicians increased component parameter margins. Currently, the telescope operates with two functioning gyros, utilizing a one-gyro mode to preserve the remaining one as a backup. This limits some scientific observations but allows the scope to continue exploring the universe’s mysteries.
NASA anticipates that the new operating parameters will extend Hubble’s life into the 2030s. However, without a boost in altitude, Hubble will eventually succumb to atmospheric drag and burn up in Earth’s atmosphere by the mid-2030s.