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Scientists release first image from Hubble in one-gyro mode

First Hubble image in one-gyro mode
Click for original image.

The Hubble science team today released the first image from the Hubble Space Telescope produced in its new one-gyro mode.

That image it so the right, cropped, reduced, and sharpened to post here, and shows NGC 1546, a nearby galaxy in the constellation Dorado about 52 million light years away. The inset shows at full resolution the small red galaxy near the top, to give some sense of the telescope’s capabilities in this one-gyro mode.

The details astonish me, and prove my pessimism about this new mode to have been wrong. I expected future images to be more fuzzy, with Hubble’s ability to take sharp images largely limited. The resolution here is excellent, and bodes well for future science observations.

Nonetheless, the telescope is still working under major limitations:

Although one-gyro mode is an excellent way to keep Hubble science operations going, it does have limitations, which include a small decrease in efficiency (roughly 12 percent) due to the added time required to slew and lock the telescope onto a science target.

As previously noted, prior to the use of the fine guidance sensors, fixed head star trackers position Hubble’s pointing closer to the target. If Earth or the moon block two of the fixed head star trackers’ fields of view, Hubble must move further along in its orbit until the star trackers can see the sky and its stars again. This process encroaches upon science observation time. Second, the additional time the fine guidance sensors take to further search for the guide stars adds to the total time the sensors use to complete the acquisition.

Third, in one-gyro mode Hubble has some restrictions on the science it can do. For example, Hubble cannot track moving objects that are closer to Earth than the orbit of Mars. Their motion is too fast to track without the full complement of gyros. Additionally, the reduced area of sky that Hubble can point to at any given time also reduces its flexibility to see transient events or targets of opportunity like an exploding star or an impact on Jupiter.

When combined, these factors may yield a decrease in productivity of roughly 20 to 25 percent from the typical observing program conducted in the past using all three gyros.

It really is time for the astronomical community to get its act together and begin work on developing and launching more large optical telescopes into space. Hubble has shown us the potential of in-space optical astronomy. That astronomers have not flocked in the last three decades to build more such telescopes is puzzling beyond belief.

Genesis cover

On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.


The print edition can be purchased at Amazon. Or you can buy it directly from the author and get an autographed copy.

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"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News


  • Clark

    I agree that the astronomical community needs to push harder to get more optical telescopes aloft (or at the very least, lobby more vocally to repair/refurbish Hubble). It seems, though, that with the advances made in adaptive optics, the momentum is very much behind the construction of large ground telescopes high up in places like the Andes mountains, perhaps for reasons of (less) cost and bureaucracy… neither of which applies to places like Hawaii, unfortunately.

    As goes the rest of the space industry, I have little doubt that it will be left to private endeavors to get the next generation of optical telescopes into space. Perhaps that is for the best?

  • Mike Borgelt

    Starship should be able to launch a nearly 9 meter single mirror telescope, larger if segmented. Then SELL access.

  • Chris

    Ok, I have seen this story on Hubble’s gyros going out for some time.
    This situation makes me ask several questions:

    Can’t a platform or “box” with three a priori aligned (X-Y-Z) gyros be simply attached to the Hubble spacecraft and then powered and have the alignment calibrate by a star calculation?

    Can’t these gyros be ring-laser-gyros that have no moving parts and lower power consumption? Is there some limitation with them that I’m unaware of? They have been around since before the Hubble launch I beleive.

  • wayne

    This is extremely informative….

    Scott Manley (June 14, 2024)
    Hubble’s Gyros

  • wayne

    definitely watch the Scott Manley video.

    in brief;
    -orientation sensing:
    Gyroscopes– the matter at hand.
    Sun-sensors- prevents telescope from accidentally pointing at the Sun
    Magnetometers- detects telescope orientation to Earth’s magnetic field.
    3 fixed head star-trackers for ‘gross’ orientation.
    Fine guidance star-trackers in instrument bay, viewing through the main mirror.

    attitude control hardware:
    Reaction wheels- conservation of angular momentum.
    Magnetorquers- removes excess angular momentum.

  • Chris:

    There were two limitations on ring-laser gyros. They were not sufficiently accurate, and had a mean-time-between-failure significantly shorter than the gas-bearing gyroscopes chosen.

  • Steven Carleton

    Maybe stunning images and break-through science from the PRC’s orbiting optical telescope will put NASA in the hot sight., Just read they refused a privately-funded mission to repair it – huh?

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