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NASA's Upcoming Webb Telescope Will Survey Saturn and Titan

Among the most intriguing solar-system targets Webb will study after its launch in 2021 are Saturn and its moon, Titan. Saturn’s weather undergoes seasons like Earth, except that they last 7-1/2 years. Occasionally, storms encircle the planet, making Saturnian weather an active field of study. Titan also experiences weather, since it is the only moon in our solar system with a substantial atmosphere. Methane rain fills surface seas that then evaporate and fuel more storms, much like the water cycle on Earth. Webb will investigate seasonal changes on both Saturn and Titan over the duration of its mission.

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Latest News

Hubble Status

January 15
This morning, the Wide Field Camera 3 was brought back to normal operations, after those operations were suspended due to an anomaly on January 8. It is expected that the Wide Field Camera 3 will start to collect science images again by the end of the week.

Shortly after noon EST on January 8, software installed on the Wide Field Camera 3 detected that some voltage levels within the instrument were out of the predefined range. The instrument autonomously suspended its operations as a safety precaution. Upon further investigation, the voltage levels appeared to be within normal range, yet the engineering data within the telemetry circuits for those voltage levels were not accurate. In addition, all other telemetry within those circuits also contained erroneous values indicating that this was a telemetry issue and not a power supply issue.

After resetting the telemetry circuits and associated boards, additional engineering data were collected and the instrument was brought back to operations. All values were normal. Additional calibration and tests will be run over the next 48 to 72 hours to ensure that the instrument is operating properly. Further investigation using both the new and the previously collected engineering data will be conducted to determine why those data values were originally incorrect.

January 09
At 17:23 UTC on January 8, the Wide Field Camera 3 on the Hubble Space Telescope suspended operations due to a hardware problem. Hubble will continue to perform science observations with its other three active instruments, while the Wide Field Camera 3 anomaly is investigated. Wide Field Camera 3, installed during Servicing Mission 4 in 2009, is equipped with redundant electronics should they be needed to recover the instrument.

October 27
Hubble resumed science operations under three-gyro control at 5:30am EDT.

October 23rd Update
On October 5, one of the Hubble gyros failed, and a reserve gyro that was powered as a replacement did not perform at the level required for operations. After two weeks of trouble shooting, that gyro is now operating well within the necessary performance limits. There are additional tests to characterize the gyro performance, and work to implement safeguards against similar performance problems should they arise again, but we are working to return Hubble to three-gyro science operations in the near future. For more details, please see the NASA press release at:

October 8th Gryo Update

NASA is working to resume science operations of the Hubble Space Telescope after the spacecraft entered safe mode on Friday, October 5, shortly after 6:00 p.m. EDT. Hubble’s instruments are still fully operational and Hubble is expected to produce excellent science for years to come.

Hubble entered safe mode after one of the three gyroscopes (gyros) actively being used to point and steady the telescope failed. Safe mode puts the telescope into a stable configuration until ground control can correct the issue and return the mission to normal operation.

Built with multiple redundancies, Hubble had six new gyros installed during Servicing Mission-4 in 2009. Hubble usually uses three gyros at a time for maximum efficiency, but can continue to make scientific observations with just one.

The gyro that failed had been exhibiting end-of-life behavior for approximately a year, and its failure was not unexpected; two other gyros of the same type had already failed. The remaining three gyros available for use are technically enhanced and therefore expected to have significantly longer operational lives.

Two of those enhanced gyros are currently running. Upon powering on the third enhanced gyro that had been held in reserve, analysis of spacecraft telemetry indicated that it was not performing at the level required for operations. As a result, Hubble remains in safe mode. Staff at NASA’s Goddard Space Flight Center and the Space Telescope Science Institute are currently performing analyses and tests to determine what options are available to recover the gyro to operational performance. Science operations with Hubble have been suspended while NASA investigates the anomaly. An Anomaly Review Board, including experts from the Hubble team and industry familiar with the design and performance of this type of gyro, is being formed to investigate this issue and develop the recovery plan. If the outcome of this investigation results in recovery of the malfunctioning gyro, Hubble will resume science operations in its standard three-gyro configuration.

If the outcome indicates that the gyro is not usable, Hubble will resume science operations in an already defined “reduced-gyro” mode that uses only one gyro. While reduced-gyro mode offers less sky coverage at any particular time, there is relatively limited impact on the overall scientific capabilities.

Announcement Notice

We are pleased to announce the release of the Cycle 27 Call for Proposals for Hubble Space Telescope (HST) Observations and funding for Archival Research and Theoretical Research programs.

This Call is provisional pending final approval by NASA.

Participation in this program is open to all categories of organizations, both domestic and foreign, including educational institutions, profit and nonprofit organizations, NASA Centers, and other Government agencies.

This solicitation for proposals will be open through April 05, 2019 8:00pm EDT. The Astronomer's Proposal Tools (APT), which is required for Phase I Proposal Submission will be released for Cycle 27 Phase I use early February. Results of the selection will be announced by the end of June 2019.

All programmatic and technical information, as well as specific guidelines for proposal preparation, are available electronically from the STScI Announcement Web Page:

Please take note of the What's New for Cycle 27 section on the announcement page.

In particular, the Director has decided to continue with the anonymous review process for Cycle 27. This follows recommendations by a working group and discussion with the Space Telescope Users Committee (presentation). The decision has been endorsed by the STUC, the Space Telescope Institute Council and the AURA Board, and is supported by NASA. A description of the process and instructions on how to adjust proposals to comply with the new requirements are included in the Call for Proposals.

Questions can be addressed to the STScI Help Desk (web: or email:

The US government is currently in a partial shutdown. Should the shutdown be extended significantly, appropriate steps will be taken to ensure that those adversely affected, including federal civil servants, are not put at a disadvantage.

Fundamental Physics with HST

Over the last three decades the Hubble Space Telescope has played a crucial role in probing key parameters relevant to fundamental physics and cosmology. The H(0) key project figured prominently in during the early years, and subsequent programs have reduced measurement uncertainties to less than 3%. More recently, Hubble has investigated other parameters, including testing the nature of dark matter through observations of merging galaxy clusters and using white dwarf spectra to constrain the gravity dependence of the fine structure constant.

Looking forward, the STScI Director convened a working group drawn from the physics and cosmology communities to provide advice on how Hubble might contribute to future investigations in fundamental physics. The committee was chaired by Prof. Bhuvnesh Jain (University of Pennsylvania), and included Prof. Neal Dalal (University of Illinois), Professor Cora Dvorkin (Harvard University), Prof. Jeremy Heyl (University of British Columbia), Prof. Marc Kamionkowski (Johns Hopkins University), Dr. Phil Marshall (SLAC National Accelerator Laboratory), and Prof. David Weinberg (Ohio State University). The committee consulted with members of the community and submitted a final report in November 2017.

The Charter can be found here as well as the Final Report.

Program Status

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HST Press Releases

Scientists please submit newsworthy items with the news release form. Also see the news release policy.

HST Daily Report


Hubble Legacy Archive

The Hubble Legacy Archive (HLA) is designed to optimize science from HST by providing online, enhanced Hubble products and advanced browsing capabilities.