A problem with one of the Hubble Space Telescope’s three remaining gyroscopes, which are critical for aiming and locking on targets, prompted mission managers to switch to a backup control mode that will limit some observations but keep the iconic observatory operating well into the 2030s, officials said. Tuesday .
“We still believe there is very high confidence and probability that we can operate Hubble very successfully doing groundbreaking science throughout the remainder of the 20s and into the 2030s,” Hubble project manager Patrick Crouse told reporters during an afternoon teleconference. .” said.
At the same time, Mark Clampin, director of astrophysics at NASA Headquarters, said the agency has ruled out a proposed commercial mission, at least for now. To take Hubble to a higher altitude Using the SpaceX Crew Dragon spacecraft. The flight was proposed by SpaceX and Crew Dragon veteran Jared Isaacman as a way to extend the life of Hubble.
increasing telescope By ascending to a higher altitude, the subtle effects of extreme outer atmospheric “drag” that slowly but surely pulls a spacecraft back to Earth can be reduced. Isaacman, the billionaire who chartered the first fully commercial flight to low Earth orbit in 2021, is training to lead three more SpaceX “Polaris” missions; That mission includes a flight this summer where he plans to become the first private citizen to participate. an open hatch and floating, if not walking, in space.
But project managers said Tuesday that Hubble is in no danger of falling back to Earth in the near future. The latest calculations show that the observatory will remain in orbit until at least 2035, allowing time to evaluate possible future options, if warranted.
“We will not be re-raising at this time after exploring existing commercial capabilities,” Clampin said. “We greatly appreciate the in-depth analysis performed by NASA and the (SpaceX-Isaacman) program and our other potential partners, and it has certainly given us a better insight into considerations for the development of a future commercial reenactment mission.
“But our assessment also raised a number of issues, including potential risks such as premature loss of science and some technological challenges. So while regeneration is an option for the future, we need to do some additional studies to determine whether it can be long-term.” We believe that the future science return will outweigh the short-term science risk.”
Hubble’s decades of service in space
The Hubble Space Telescope was launched aboard the shuttle Discovery on April 24, 1990; The opening chapter of an unlikely story in which a defective mirror and spacewalking repair crews transform a national embarrassment into an international science icon.
Hubble was initially hobbled by an error during the manufacture of the 94.5-inch primary mirror that resulted in an optical defect known as spherical aberration that prevented the telescope from bringing starlight into sharp focus.
But engineers quickly found a way to correct Hubble’s blurry vision. They designed a new camera equipped with grounded relay mirrors according to the instructions that would completely eliminate the aberration of the primary mirror. Another device, known as COSTAR, was designed to direct corrected light to Hubble’s other instruments.
During a shuttle shuttle mission in December 1993, the new Wide Field Planetary Camera 2 and COSTAR were installed by spacewalking astronauts. They also replaced Hubble’s solar panels and other critical components.
NASA will launch four more servicing missions, installing new, state-of-the-art instruments and replacing obsolete components such as critical precision orientation sensors and gyroscopes that move the telescope from target to target and then lock with floating objects. Solid stability for detailed observations.
Gyroscopes are critical to Hubble’s longevity. The telescope was launched with six ultra-stable gyroscopes, but only three gyroscopes were needed at a time for normal operation. During the last maintenance mission in 2009, all six vehicles were replaced. Three of the new units contained components susceptible to corrosion of some kind; the other three had an improved design that greatly reduced or eliminated this risk.
In any case, by 2020, Hubble’s 30th anniversary, three of the six older model gyroscopes had failed.
Gyroscope number 3, one of the remaining three units, began to act erratically early on and its performance gradually deteriorated. On May 24, the gyroscope was taken offline and the observatory was placed in a protective “safe mode” and scientific work was halted while engineers discussed their options.
Knowing that gyroscope failures were inevitable, engineers previously developed software that allowed Hubble to operate with just two gyroscopes, or even one. The downside was that the telescope could only reach targets in about half the sky at any given time, rather than 85% or more with three gyroscopes.
Although the telescope could be operated more efficiently with two gyroscopes, engineers concluded that it would make more sense to put one of the two remaining healthy units in standby mode and operate Hubble with only one gyroscope, keeping the other in reserve. as needed.
“Our team first developed a plan for single gyroscope operations more than 20 years ago, and this is the best way forward to extend Hubble’s lifespan,” Crouse said. “There are some limitations. It will take us more time to move from one target attitude to another and to lock in on that scientific target.
“This will lead to lower efficiency for planning scientific observations. We currently plan about 85 orbits per week and expect (to be) able to plan about 74 hours per week, so about a 12% reduction in planning efficiency.”
In addition, because the telescope’s motion in single-gyroscope mode is less precise and prone to error, “we won’t have as much flexibility in terms of where in the sky we can observe at any given moment. But for a period of time” we will have the entire sky at our disposal.
Another limitation is that the telescope will not be able to lock on to and track targets closer to Mars’ orbit, but such observations were rare even in three-gyroscope mode.
Meanwhile, engineers plan to implement single gyro control mode in the coming days and return Hubble to science operations by the middle of the month.
“We updated the reliability assessments of the gyroscopes… and still conclude that we have a greater than 70 percent chance of operating at least one gyroscope by 2035,” Crouse said.
The infrared-sensitive James Webb Space Telescope builds on Hubble’s legacy, pushing deeper into space and time, producing a steady stream of discoveries as it moves to the forefront of space-based astronomy. But Hubble is still making world-class observations, and astronomers want to keep it operational for as long as possible.
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