June 22, 2024

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NASA says the Hubble Space Telescope faces a setback, but should continue to operate for years

NASA says the Hubble Space Telescope faces a setback, but should continue to operate for years

A problem with one of the Hubble Space Telescope’s three remaining gyroscopes, which are essential for aiming and stabilizing targets, has prompted mission managers to switch to a backup control mode that will limit some observations but will keep the famed observatory running well into the 2030s, officials said. Tuesday.

“We still believe that there is a very high reliability and probability that we will be able to operate Hubble very successfully, and do groundbreaking scientific research, during the remainder of the 2020s and into the 2030s,” Hubble project manager Patrick Cross told reporters during an afternoon conference call. .

The Hubble Space Telescope as seen during the Space Shuttle servicing mission.


Meanwhile, Mark Clampin, director of astrophysics at NASA Headquarters, said the agency has ruled out, at least for now, a proposed commercial mission. To boost 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 Hubble’s life.

By reinforcement Telescope At a higher altitude, the subtle effects of “drag” in the intense outer atmosphere, which slowly but surely pulls the spacecraft back to Earth, can be reduced. Isaacman, the billionaire who chartered the first full commercial flight to low-Earth orbit in 2021, is training to lead three more SpaceX “Polaris” missions, including one this summer in which he plans to become the first private citizen to stand on. The hatch opens and you float, if not walk, in space.

But project managers said Tuesday that Hubble is not in danger of returning to Earth anytime soon. The latest calculations show that the observatory will remain in orbit until at least 2035, allowing time to consider possible options, if necessary, in the future.

“After exploring existing commercial capabilities, we will not proceed with the reconsolidation process now,” Clampin said. “We greatly appreciate the in-depth analysis conducted by NASA, SpaceX-Isaacman, and our other potential partners, and it has certainly given us a better look at the considerations for developing a future commercial relaunch mission.

“But our assessment also raised a number of considerations, including potential risks such as losing science prematurely and some technological challenges. So, while rebooting is an option for the future, we believe we need to do some additional work to determine whether the long term will continue.” or not”. – The long-term scientific return will outweigh the short-term scientific risks.

Decades of Hubble’s service in space

The Hubble Space Telescope was launched aboard the shuttle Discovery on April 24, 1990, with a famously flawed mirror, the opening chapter of an unlikely tale in which spacewalk repair crews turned a national embarrassment into a global symbol of science.

Hubble initially malfunctioned due to an error during the manufacturing of the 94.5-inch primary mirror, which resulted in an optical defect known as spherical aberration, which prevented the telescope from bringing starlight into sharp focus.

But engineers quickly discovered a way to correct Hubble’s blurry vision. They designed a new camera with prescription ground relay mirrors that would completely counteract the aberration of the primary mirror. Another device, known as COSTAR, is designed to direct corrected light to other Hubble instruments.

During the shuttle servicing mission in December 1993, the new Wide Field Planetary Camera 2 and COSTAR were installed by astronauts. They also replaced Hubble’s solar panels and other important components.

NASA will continue to fly four more servicing missions, installing new, state-of-the-art instruments and replacing aging components such as precise guidance sensors and critical gyroscopes, which move the telescope from target to target and then attach it to rocks. Strong stability for detailed notes.

Gyroscopes are essential to Hubble’s longevity. The telescope was launched equipped with six ultra-stable gyroscopes, but only three are needed at a time for normal operation. During the final service mission in 2009, all six were replaced. Three of the new units included components susceptible to some form of corrosion, while the other three units featured an improved design that significantly reduced or eliminated this risk.

However, by Hubble’s 30th anniversary in 2020, all three of the six older models had failed.

One of the remaining three units, Gyroscope No. 3, had started working intermittently earlier, and its performance gradually deteriorated. On May 24, the gyroscope was turned off, placing the observatory in a protective “safe mode,” halting scientific operations while engineers discussed their options.

Since gyroscope failure is inevitable, engineers had previously developed software that would allow Hubble to operate with just two or even one gyroscope. The downside is that the telescope can only reach targets in about half the sky at any given time instead of 85% or more with the three gyroscopes.

Although the telescope could be operated more efficiently using two gyroscopes, the engineers concluded that it would make sense to put one of the two remaining intact units on standby and operate Hubble with only one gyroscope, keeping the other in reserve for use. as it is required.

“Our team first developed a plan for single gyro operations more than 20 years ago, and this is the best position going forward to extend Hubble’s life,” Cross said. “There are some limitations. It will take us more time (to move) from one target situation to another and to be able to stick to that science target.

“This will result in reduced scheduling efficiency for science observations. We currently schedule about 85 orbits per week and expect (to be) able to schedule about 74 hours per week, an approximately 12% reduction in scheduling efficiency.”

Additionally, because the telescope’s movement in single gyroscope mode is less precise and error-prone, “we won’t have as much flexibility as to where in the sky we can observe at any given time. But over a period of time, next year, the sky will be all available to us.”

Another limitation is that the telescope would not be able to identify and track targets closer to Mars’ orbit, although such observations were rare even in three-gyroscope mode.

Meanwhile, engineers plan to implement single-gyroscope control mode in the coming days, and return Hubble to science operations around the middle of the month.

“We have updated the reliability assessments of the gyroscopes… and still come to the conclusion that (we have) more than a 70 percent probability of operating at least one gyroscope until 2035,” Cross said.

The James Webb Space Telescope builds on Hubble’s legacy, delving into space and time and producing a steady stream of discoveries as it moves to the forefront of space astronomy. But Hubble is still making world-class observations, and astronomers want to keep it running for as long as possible.

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