Composite of ultraviolet light images from the LEGUS survey

Hitting New Milestones

Learn how staff at the institute led Hubble’s trailblazing science operations in 2018.

The Hubble Space Telescope, an international collaboration between NASA and the European Space Agency, has flown for more than 28 years. Each year, our teams work to ensure this observatory is not only operating at peak performance, but also continuing to shape the field of astronomy. In 2018, staff introduced a dual-anonymous proposal process and updated Hubble’s instruments’ capabilities. This year, more than 950 peer-reviewed papers using Hubble data were published in scientific journals.

Introducing Proposal Anonymity

How do you continue to democratize science? By focusing on the scientific merit of the applications for observing time on Hubble—not on the people who apply. Studies have shown that gender, professional affiliation, number of years of experience, and country of origin influence reviewers’ decisions about which teams’ science proposals they recommend. For these reasons, a working group at the institute has focused for several years on decreasing the effects of unconscious biases.

In October 2018, the institute took another big step by implementing a dual anonymous proposal process for Hubble—the first in the field of astronomy. The new requirements did not deter proposers. In fact, applications to observe with Hubble increased, although this was mostly due to a change in the types of proposals accepted. Twelve times more orbits were requested than time allowed in 2018 (in 2017, it was five to one).

The approach, which was thoroughly researched and widely discussed with members of the astronomical community, means that proposers did not know who the reviewers were, and—most importantly—the committee had no insight into who the proposers were until after the official rankings were set. Now, whenever teams submit a proposal to use Hubble, their documents are reviewed strictly based on scientific merit.

While the proportion of proposals submitted and led by women remained the same compared to previous cycles, their acceptance rates rose, putting them at a rate statistically equal to proposals led by men. This work will continue at the institute, allowing our staff to measure the outcomes of the approach, with the goal of achieving a more even gender balance among all proposers. This new approach will become standard procedure both for Hubble and future observatories the institute oversees, including NASA’s James Webb Space Telescope.

Restoring Gyro Operations

Field of galaxies DSF2237b
The first image Hubble captured after returning to science shows a field of galaxies in the constellation Pegasus. The observations were taken with the Wide Field Camera 3 to study very distant galaxies in the field. Credits: NASA, ESA and A. Shapley (UCLA).

On October 5, one of Hubble’s four remaining gyroscopes failed, causing the mission to temporarily pause its operations. (Three gyros are required for optimal scientific observations.) Almost immediately, more than a dozen team members gathered in the control room at NASA’s Goddard Space Flight Center to assess the situation, supported by planning and scheduling teams at the institute. Only a few weeks later, Hubble officially returned to normal science operations.

These teams had extensively trained for this day for years. After being unable to turn the failed gyro back on, they switched on a more advanced gyro that was installed in 2009, but had not been turned on since 2011. However, it soon began reporting impossibly high rotation rates for the telescope—around 450 degrees per hour, when Hubble was actually turning less than a degree per hour. Because three gyros are required for optimal scientific efficiency, the team extensively tested creative solutions to solve the problem.

Ultimately, after suspecting an obstruction that may have affected the gyro’s readings, the team repeatedly switched the gyro between operational modes and rotated the spacecraft. In response, the erroneously high rotation rates from the gyro gradually fell until they were close to normal. On October 27, Hubble targeted a field of galaxies and recorded an image, continuing its long history of science operations.

Installing Regular Upgrades

Every year, teams that support Hubble are focused on updating the capabilities of its four operating instruments with new observing modes and tools, because tweaking the way Hubble makes observations and how we process the data can open up researchers’ ability to make new discoveries. In 2018, the teams implemented several new capabilities. First, a searchable database of 22 million objects from the institute’s archives allows researchers to look at the precise shapes of stellar images. In turn, users can accurately model the behavior of the Wide Field Camera 3 instrument’s ultraviolet-visible channel and make sensitive light measurements when analyzing Hubble’s data. Teams also released a new source catalog and spectroscopic archive to support ongoing research and enable new studies.

Next, a new observing mode on the Space Telescope Imaging Spectrograph was created and implemented, which makes it easier to obtain high-quality spectra of extremely bright stars and to remove interference effects at longer wavelengths by carefully sliding the target star across the camera. This means researchers can monitor a star’s apparent brightness at particular wavelengths, which will help them characterize exoplanets and their atmospheres by using these high-precision measurements. This is especially meaningful because this instrument has been aboard Hubble for more than 20 years; implementing new modes demonstrates its agility to respond to evolving science demands. New observing modes were also implemented for Hubble’s Cosmic Origins Spectrograph, which improved its observing efficiency at short wavelengths.

All of this work supports the institute’s efforts to extend Hubble’s capabilities through the mid-2020s and ensure that this prolific observatory will continue to make unprecedented discoveries.

Illustration of planet and moon around Kepler-1625
Astronomers combed through NASA’s Kepler Space Telescope data and went on to combine it with 40 hours of new observations using Hubble to hone in on evidence for what could be the first discovery of a moon orbiting a planet outside our solar system. Scientists monitored the planet before and during its 19-hour transit across the face of its star, Kepler-1625. After the transit ended, Hubble detected a second and much smaller decrease in the star’s brightness approximately 3.5 hours later. This small decrease is consistent with a gravitationally bound moon trailing the planet. Illustration credit: NASA, ESA, and L. Hustak (STScI).