Team Hubble: Servicing Missions: From Servicing to Science

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From Servicing to Science

When the crew of the Space Shuttle Atlantis released the Hubble Space Telescope to return to orbit, concluding the final astronaut mission to upgrade and repair Hubble, astronomy fans around the world rejoiced. Hubble, renewed and equipped with new cameras, would now return to its work of revealing the universe.

But after the furor and high-profile feats of a servicing mission, Hubble sinks into silence. This time, a three-month hiatus separated the mission and the new images.

The quiet belied the intense activity going on behind the scenes. After a servicing mission, engineers and scientists conduct a slow, painstaking process called Servicing Mission Observatory Verification (SMOV) -- bringing the telescope to full functionality, making the adjustments and gathering the information that allows them to provide the best, clearest, cleanest images. SMOV operations pave the way for Hubble to take its Early Release Observations (EROs), images intended to demonstrate the telescope's new technology.

At the Space Telescope Science Institute in Baltimore, Md., and Goddard Space Flight Center in Greenbelt, Md., teams worked together after Servicing Mission 4 (SM4) to ensure that the telescope was pointing correctly and that its instruments were working with their intended precision.

Hubble's pointing is adjusted with the help of six gyroscopes, all of which were replaced during Servicing Mission 4. To ensure that the telescope was pointing accurately, engineers changed the direction of the telescope in a measured way, and then examined the data generated by the gyroscopes. The data was then used to calibrate the gyroscopes to ensure precise pointing.

Next, engineers and scientists looked at Hubble's instruments. The instruments go through a natural process of "outgassing" — the extra, unwanted molecules within them from their time on Earth float away due to the lack of atmospheric pressure.

Outgassing is important for a couple of reasons: the molecules can interfere with the instrument when high voltages are present, possibly damaging it; and they can absorb wavelengths of light, preventing the instrument from collecting all the information it could. To avoid these dangers, engineers waited until the outgassing was complete before bringing the instruments to full power.

Weightless for the first time in the vacuum of space, the new instruments were out of alignment, as expected. The instruments are built with mechanisms that allow engineers to adjust them from the ground, often by moving small mirrors within the instrument itself. Each instrument needed a few weeks to go through the alignment process.

Finally, engineers took the instruments through a calibration process. Calibration is the process of identifying and dealing with data that belongs to the instrument, versus data that belongs to the sky.

Engineers observed a familiar astronomical object and compared the data they received with the data they knew should be there. They then adjusted the instruments to remove the data that emerged from the instrument itself, or, more frequently, arranged to have it removed on the ground. Finding and identifying this erroneous data is a major part of the SMOV process.

Once all these tasks reached a satisfactory point, Hubble began taking its EROs, the first high-quality images from the telescope. The targets were chosen in advance by a team that selects them for their ability to showcase Hubble's new capabilities. The goal is to provide the most impressive views of a good mix of astronomical objects — some within the galaxy, some far beyond.

The new images were the first true display of the power of Hubble's new technology, dazzling amateur and professional astronomers with a wealth of new information. Scientists were immediately granted access to the images for use in their research upon their release in September.

Once the ERO images were completed, Hubble returned to the day-to-day task of observing the universe. Equipped with new eyes and fresh technology, it works ceaselessly, minute by minute, to answer the pressing questions of modern astronomy. Though the servicing missions may be over, Hubble's revelations will continue far into the future.

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October 20, 2009

The Cosmic Origins Spectrograph has finished SMOV calibrations and is conducting science observations. All instruments with the exception of the Near-Infrared and Multi-Object Spectrometer (NICMOS) have completed their SMOV programs. NICMOS, which is nearing SMOV completion, is undergoing data analysis to determine whether some optical adjustments should be made.

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September 18, 2009

The Cosmic Origins Spectrograph is beginning to conduct science observations as it wraps up its SMOV calibrations. All other instruments except the Near-Infrared and Multi-Object Spectrometer (NICMOS) have completed their SMOV programs and been approved for science operations. NICMOS is beginning its SMOV activities, which will last several weeks.

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September 9, 2009

 

The Early Release Observations, images highlighting Hubble's upgraded capabilities following Servicing Mission 4, have been released. See the news release.

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September 4, 2009

 

Hubble's Early Release Observations, the first observations intended to showcase the upgraded and repaired telescope's new abilities, are complete and being readied for release on Sept. 9. Calibrations required to bring the instruments to the precision necessary for scientific analysis continue, but the pace is slowing down as a large percentage of this work is complete. The observatory is already doing high-priority science, and analysis of the incoming data shows no major problems.
 
The Near-Infrared and Multi-Object Spectrometer (NICMOS) SMOV activities were deliberately scheduled for later in the year. The NICMOS SMOV will begin in mid-September. The cooling system temperature has been set and the instrument is working toward achieving a stable temperature.
 

 

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August 18, 2009

 

Hubble is getting closer to completing the calibrations for most of its instruments, and each day it draws nearer to becoming a fully functioning observatory again. In fact, in the upcoming weeks, Hubble will concentrate on making high-priority science observations and then finish the remaining instrument calibrations by early fall.

  • The Wide Field Camera 3 (WFC3) still has a few checkouts to complete, but it is now taking science images on a regular basis.
  • The Space Telescope Imaging Spectrograph (STIS) is also nearing the end of its calibration activities, which should be mostly finished by next week. Meanwhile, STIS is completing its work in support of Hubble’s Early Release Observations (EROs), which will be shared with the public in September.
  • The Cosmic Origins Spectrograph (COS) is in the final phases of its calibrations for both its near-ultraviolet and far-ultraviolet channels. The channels, which study different wavelengths of ultraviolet light, must be calibrated separately. For example, engineers and scientists are continuing to test the focus for the far-ultraviolet channel, while the near-ultraviolet channel’s focus appears to be good.
  • The cooling system for the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) has cooled the instrument down to operational levels. Engineers plan to turn on its detectors later this week. After they determine that the temperature is stable and cold enough for science observations, engineers and scientists will begin the several-week calibration process for NICMOS.
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August 7, 2009

 

As the first week of August comes to a close, most of Hubble’s science instruments have already completed or are close to completing their calibration activities. Each instrument has multiple channels that detect different wavelengths of light, and each channel must be tested and calibrated individually. While some instrument channels are still under evaluation, several others are already at work studying the universe.

 
  • The Wide Field Camera 3 (WFC3) is nearing the end of its calibrations. Most calibrations for WFC3 should be completed next week. The camera has already completed enough of its calibration work to start taking images. It is continuing to take additional Early Release Observations (EROs), which will be shared with the public in about a month.
  • Both the far-ultraviolet and near-ultraviolet channels of the Cosmic Origins Spectrograph (COS) continue to undergo calibrations as well. This week, scientists and engineers have been instructing COS to take measurements to check, among other things, the instrument’s sensitivity to light. Calibrations for COS will continue into September.
  • The near-ultraviolet and far-ultraviolet channels of the Space Telescope Imaging Spectrograph (STIS) are also finishing up their calibration activities. The near-ultraviolet channel has shown higher-than-expected levels of internal (“dark”) current, which engineers think might be due to the instrument being off since suffering a power supply failure five years ago this week. Engineers are making adjustments to accommodate for the extra current, and the adjustments appear to be working well so far. Calibrations will continue through next week.
     
    Having quickly completed its calibrations, the STIS CCD channel took its first Early Release Observation at the end of June and will take another one later this month. The channel is routinely performing science operations.
  • Following a failed attempt last week to restart the cooling system of the Near Infrared Camera and Multi-Object Spectrometer (NICMOS), engineers solved the problem and successfully restarted the cooling system on August 1. To their surprise and delight, NICMOS appears to be cooling more efficiently (faster) than expected.
     
    Because NICMOS observes infrared wavelengths, which we detect as heat, the instrument has to be cold enough so that the heat of its own electronics doesn’t interfere with observations. It will take at least another week, possibly more, for NICMOS to reach operational temperatures of less than –321 degrees Fahrenheit (–196 degrees Celsius). Then the instrument team will have to wait a little while longer to make sure the temperature stabilizes sufficiently for science observations. At that point, engineers expect to be able to turn on NICMOS and begin its calibrations then.
 
 
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July 31, 2009

 

After a quick detour into taking science observations, Hubble is back to alignment and calibration activities. Each instrument has a number of channels that detect and process different wavelengths. Some of these channels have been approved for science observations at this point, others are still works in progress.
 
  • The Cosmic Origins Spectrograph's far-ultraviolet channel is now fully aligned, and calibrations have begun.
  • Engineers resumed operations of the two remaining channels of the Space Telescope Imaging Spectrograph (STIS) this week. The instrument had been suspended due to a memory anomaly. STIS's far-ultraviolet and near-ultraviolet channels will begin internal calibrations. STIS's CCD channel, which is geared toward visible wavelengths, has already been approved for science observations.
  • Calibration resumed on both channels of Wide Field Camera 3 (WFC3) after last week's unscheduled but successful foray into planetary imaging. The Jupiter impact observations caused a small delay in the calibration process, but nonetheless, WFC3 has begun taking its first official science observations, called the Early Release Observations.
  • Engineers attempted to restart the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) cooling system, but it failed again after 12 hours. NICMOS was technically not part of Servicing Mission 4, but experts had decided to wait until after Servicing Mission 4 to turn the instrument back on after an anomaly caused it to go into "safe mode" in September 2008.

 

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July 24, 2009

 

NASA interrupted Hubble testing and calibration to take a picture on July 23 of a new impact site on Jupiter. The expanding spot, discovered by an amateur astronomer earlier in the week, was probably caused by a comet or asteroid striking the planet. The rareness of the event impelled astronomers to pause SMOV activities to take the image. The image was taken by the new Wide Field Camera 3, even though it is not completely calibrated, and thus not at its full power. See the news release.

Scientists and engineers plan to resume Space Telescope Imaging Spectrograph work and will attempt to restart the Near Infrared Camera and Multi-Object Spectrometer cooling system next week.

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July 20, 2009

During Servicing Mission 4, astronauts replaced many key parts – batteries and gyroscopes, for example -- that affect the spacecraft component of the Hubble Space Telescope. Testing and calibration for the spacecraft itself is now complete, and that aspect of Hubble is in excellent shape.

  • Hubble is now functioning with three of its six new gyroscopes. As planned, the other three have been turned off to keep in reserve.
  • Hubble's new batteries are performing as expected, with more charging capacity than the ones they replaced.
  •  The new thermal panels are functioning as anticipated, keeping equipment Bays 5, 7, and 8 at their expected temperatures.

Testing and calibration continues on the science components.

  •  The Science Instrument Command and Data Handling Unit (SIC&DH) has been turned on again after its June electronic malfunction, and is functioning normally. The problem has not reoccurred. Engineers continue to monitor the SIC&DH.
  • All instruments contain a number of channels, which detect and processes different wavelengths. Wide Field Camera 3 is now aligned and focused in both of its channels, and is undergoing calibration.
  • Scientists and engineers have nearly finished aligning the Cosmic Origins Spectrograph (COS). When an instrument enters space, weightlessness can cause it to go out of alignment. Engineers adjust the instrument from the ground, controlling tiny mirrors inside the instrument. One channel is fully aligned, and the other's alignment should be completed over the next few days. COS's other planned calibrations, typically involving internal measurements of the instrument, are going well. The COS far-UV channel successfully conducted its first external observation this week in preparation for the alignment process.
  • The Space Telescope Imaging Spectrograph has been suspended due to a memory anomaly. Engineers are working on the problem.
  • The Advanced Camera for Surveys (ACS) has completed all testing, alignment and calibration activities and is taking science observations. Two of the instrument's channels – one seeing ultraviolet light, the other visible light -- are functioning very well. The third, a high-resolution channel that, for example, takes pictures of the central regions of galaxies, could not be restored during the servicing mission. This channel was thought to have a 50-50 chance of being brought back online, so the result is not unexpected. The return of the visible light channel, responsible for many of ACS's famous images, is a particular triumph.

 

 

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July 10, 2009

Since the conclusion of Servicing Mission 4, engineers and scientists have been conducting the painstaking process of testing and reactivating Hubble components in order to bring the telescope back to full science operations. The ambitiousness of the servicing mission, with the installation of two new instruments, repair of two others, and the replacement of the Science Instrument Command and Data Handling Unit (SIC&DH) and a Fine Guidance Sensor (FGS), means testing, alignment and calibration activities are extensive, but much progress has been made.
 
On June 15, an electronic malfunction occurred in the replacement SIC&DH, which helps command the science instruments and directs the flow of data within the telescope before it is transmitted to Earth. Protective shutdowns of instruments and computer data indicated that the problem had occurred. Investigations narrowed the malfunction down to a single component, which is now functioning without issues.
 
The malfunction may not occur again, and the probability of damage if it did is very small, but engineers are devising protective measures to ensure the safety of Hubble’s instruments in case of a repeat performance. The creation of these measures has delayed some of the regular testing and reactivation activities, including the alignment of the instruments. Hubble instruments go out of alignment when they are exposed to weightlessness for the first time and are built with mechanisms that allow engineers to adjust them from the ground, often by moving small mirrors within the instrument itself.
 
Each instrument contains a number of “channels.” Each channel detects and processes different wavelengths. After putting all instruments into a protective safe mode while examining the SIC&DH malfunction, engineers and scientists were able to resume work on several individual channels. Others were kept inactive until safety measures could be defined and implemented.
  • The Wide Field Camera 3 (WFC3) is well on its way to achieving its planned alignment and focusing milestones. Both channels of WFC3 continue to undergo focusing and alignment. The instrument has already been successfully exposed to its first light from space.
  • The Advanced Camera for Surveys (ACS) was placed in protective mode two weeks ago, due to an electronics glitch.  It has since been returned to operations. Testing is progressing normally and is almost complete.
  • The Space Telescope Imaging Spectrograph had two channels suspended due to the SIC&DH problem, but protective measures are now in place. This instrument is expected to be back in operation by the week of July 13. One of its channels had already been approved for science operations and the other two are close to being approved.
  • The Cosmic Origins Spectrograph is partway through the alignment process and internal measurements look good. One channel is being calibrated. The other channel has resumed testing after installation of protective measures related to the SIC&DH event.
  • Fine Guidance Sensors were unaffected by the SIC&DH problem and continued operations and testing. The refurbished FGS installed during SM4 has been approved for use as one of the guiders for the pointing control system, and can now do its part to help position the telescope.

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