NASA’s Hubble Space Telescope is back in action exploring the universe near and far. Scientific instruments are back in full operation, after recovering from a computer error that halted telescope observations for more than a month.
Scientific observations resumed on the afternoon of Saturday 17 July. The telescope’s targets last weekend included the unusual galaxy shown in the image below.
“I’m delighted to see that Hubble has reconsidered the universe, once again capturing the kinds of images that have intrigued and inspired us for decades,” said Bill Nelson, NASA Administrator. “This is a moment to celebrate the success of a team who are truly dedicated to that mission. Through their efforts, Hubble will continue its 32nd year of discovery, and we will continue to learn from the observatory’s transformative vision.”
This snapshot, from a program led by Julian Dalcanton of the University of Washington in Seattle, shows a galaxy with unusually long spiral arms and the first high-resolution glimpse of a colliding pair of galaxies. Other major targets of the Hubble telescope include globular star clusters and the aurora borealis on the giant planet Jupiter.
These images, from a program led by Julian Dalcanton of the University of Washington in Seattle, show Hubble’s return to full scientific operation. [Left] ARP-MADORE2115-273 is a rarely observed example of a pair of interacting galaxies in the Southern Hemisphere. [Right] ARP-MADORE0002-503 is a large spiral galaxy with very long spiral arms. While most disk galaxies have an even number of spiral arms, this galaxy has three. Credits: Science: NASA, ESA, STScI, Julianne Dalcanton (UW) Image Processing: Alyssa Pagan (STScI)
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Hubble’s payload computer, which controls and coordinates scientific instruments aboard the observatory, abruptly stopped on June 13. When the main computer fails to receive a signal from the payload computer, the Hubble Science Instrument will automatically enter safe mode. This means that the telescope is no longer doing science while mission specialists analyze the situation.
The Hubble team moved quickly to investigate what hit the observatory, which orbits about 340 miles (547 kilometers) above Earth. Working from the mission control center at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, as well as remotely due to COVID-19 restrictions, engineers are collaborating to figure out what’s causing the problem.
To complicate matters further, Hubble was launched in 1990 and has been observing the universe for more than 31 years. To repair a telescope built in the 1980s, the team had to draw on the knowledge of the staff throughout its long history.
Hubble alumni have returned to support the current team in recovery efforts, and lend decades of experience to the mission. For example, a retired employee who helped build a telescope knows the entrance and bay of the Science Instruments, the command and data processing unit, where the payload computer is located—an experience that is critical to determining the next steps of recovery. Other former team members provided assistance by searching for the original Hubble paper, finding documents aged 30 to 40 years that would help the team chart a path forward.
On June 13, 2021, the Hubble Space Telescope’s payload computer suddenly shut down. However, the Hubble team has systematically identified possible causes and how to compensate for them. Credit: NASA Goddard Space Flight Center
“This is one of the advantages of a program that has been in operation for more than 30 years: an incredible amount of expertise and experience,” said Nzinga Tal, director of Hubble’s Anomaly Systems Response at Goddard. “It is humbling and inspiring to be involved with the current team and those who have moved on to other projects. There is so much dedication to their Hubble teammates and the observatory and science that Hubble is known for.”
New and existing team members work together on a list of potential causes, trying to isolate the problem to ensure they have a full future stockpile of working devices.
At first, the team thought the most likely problem was a memory module malfunction, but switching to a spare module failed to fix the problem. The team then designed and conducted tests, including turning on the Hubble telescope’s backup payload computer for the first time in space, to determine if two other components could be responsible: a standard interface device, which links communications between the computer’s CPU and other components, or the central processing unit. alone. However, booting the backup computer doesn’t work, eliminating that possibility as well.
The team then proceeded to explore whether other devices were at fault, including the data science command/coordinator unit and power controller, designed to ensure a steady supply of voltage to the computer. However, it would be more complex to solve any of these problems, and would be more dangerous for telescopes in general. Switching to this component backup module also requires switching many other hardware boxes.
Nzinga Tull, Hubble System Anomaly Response Manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, works in the control room on July 15 to return Hubble to full science operations. Credit: NASA GSFC/Rebecca Roth
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“The switch takes 15 hours of driving the spacecraft from Earth. The main computer must be turned off, and the safe mode backup computer temporarily takes over the spacecraft. Some of the boxes also need to be turned on,” said Jim Gilletick, deputy director of the Hubble project at Goddard. They have never been run in space, and other devices will need to swap their interfaces. “There’s no reason to think that none of this will work, but the team’s job is to get nervous and think about everything that could go wrong and how we can make up for it. The team carefully planned and tested every little step on the pitch to make sure they got it right.”
The team carefully and methodically started from there. Over the next two weeks, more than 50 people worked to review, update, and review the procedure for switching to a backup device, and testing it in HD Simulation and a formal review of the proposed plan.
At the same time, the team analyzed data from their previous tests, and their findings suggest that the power controller is the likely cause of the problem. On July 15, they made a planned switch to a Science Instrument backup and command and data processing unit, which contains a backup power control unit.
The win came around 11:30 a.m. EST on July 15, when the team decided the switch was a success. Scientific instruments were then put into operation, and Hubble began retrieving scientific data again on July 17. Most observations lost while scientific operations are suspended will be rescheduled.
This isn’t the first time Hubble has had to rely on spare hardware. The team made a similar switch in 2008, returning Hubble to normal operation after another part of the Science Instrument and Command & Data Handling (SI C&DH) module failed. The Hubble telescope’s last maintenance mission in 2009 – a much-needed tuning championed by former US Senator Barbara Mikulsky – later replaced the entire SI unit of C&DH, significantly extending Hubble’s operational life.
Since this service mission, Hubble has made more than 600,000 observations, bringing its total age to over 1.5 million. These observations continue to change our understanding of the universe.
Members of the Hubble Operations Team work in the control room on July 15 to return Hubble to operations science. Credit: NASA GSFC/Rebecca Roth
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“Hubble is in good hands,” said Kenneth Simbach, director of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, which carried out Hubble’s science operations. “I have been impressed by the team’s dedication and shared goal over the past month to bring Hubble back into operation. Now that Hubble is once again providing an unprecedented view of the universe, I fully hope that Hubble will continue to amaze us with many scientific discoveries in the future.”
Hubble has contributed the most Important discoveries of our universe our, including the accelerated expansion of the universe, the evolution of galaxies over time, and the first studies of the atmospheres of planets outside our solar system. His mission has spent at least 15 years exploring the farthest and weakest regions of the universe, and is still far beyond that goal.
“The record-breaking amount of science presented by Hubble is staggering,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate. “We have a lot to learn from the next chapter in Hubble’s life — by itself, along with the capabilities of other NASA observatories. I’m very pleased with what the Hubble team has accomplished over the past few weeks. They have faced the challenges of this process head-on, ensuring that Hubble’s exploration days are not over.”
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