After Two Long Careers, QuikSCAT Rings Down the Curtain

NASA – SeaWinds scatterometer QuikSCAT Mission patch.

October 13, 2018

Launched in June 1999 for an intended two-year mission, NASA’s SeaWinds scatterometer instrument on the QuikSCAT spacecraft was turned off on Oct. 2 in accordance with its end-of-mission plan. QuikSCAT spent its first decade creating an unprecedented record of the speed and direction of winds at the ocean surface. Then, for another nine years, it served as the gold standard of accuracy against which new spaceborne scatterometers were calibrated.

Image above: QuikSCAT imaged winds during many storms, including Hurricane Katrina, shown here covering the Gulf of Mexico in August 2005. Highest wind speeds appear purple, with winds weakening outward from the eye. Barbs show wind direction; white barbs indicate heavy rainfall. Image Credits: NASA/JPL-Caltech.

Managed by NASA’s Jet Propulsion Laboratory in Pasadena, California, QuikSCAT was a unique national resource that far surpassed NASA’s original science objective for the mission. During its 10 years of observing winds over the global ocean surface, QuikSCAT measurements were used by the world’s weather forecasting agencies to improve forecasts and identify and monitor hurricanes and other storms far out in the open seas. Its data also provided critical information for monitoring, researching, modeling, and forecasting the atmosphere, ocean, ice and climate.

Among its many accomplishments:

• QuikSCAT discovered that hurricane-strength winds occur frequently in the North Atlantic and North Pacific oceans, where such strong winds were not previously expected to exist.

• It provided high-resolution observations of the dramatically accelerating changes in sea ice cover on the Arctic Ocean.

• The mission’s measurements were used widely beyond weather forecasting and research — for example, to help identify efficient shipping routes, plan new offshore wind farms, and guide search-and-rescue operations at sea.

Michael Freilich, the QuikSCAT mission’s original principal investigator and now director of NASA’s Earth Science Division, noted, “QuikSCAT operated in space for nearly two decades, and we are certain that its impact and legacy will last much longer.”

Ernesto Rodríguez, QuikSCAT project scientist at JPL, said, “The decommissioning of QuikSCAT marks the passing of an era. Many scientists and forecasters have built their careers over the last 20 years using QuikSCAT. Its data led to major discoveries on the interaction between the ocean and the atmosphere.”

A few months after QuikSCAT’s 10th anniversary, an age-related problem caused its spinning antenna to stop rotating, reducing its observing swath to only 19 miles (30 kilometers) wide. The extreme accuracy of this narrow swath measurement, however, allowed QuikSCAT to take on a second mission: calibrating newer satellites to enable a much longer data record of ocean winds.

SeaWinds scatterometer QuikSCAT spacecraft. Image Credits: NASA/JPL

Satellite instruments are regularly calibrated to ensure their readings match other data that are known to be accurate, and to correct for an instrument’s normal drift in accuracy over time. QuikSCAT’s exceptional stability made it invaluable in assuring that newer missions from the Indian and European space agencies and from NASA are providing apples-to-apples measurements. This function proved so important to the research community that QuikSCAT’s decommissioning was postponed twice to allow time for new scatterometers to be launched and calibrated.

QuikSCAT project manager Rob Gaston of JPL said, “It’s a testament to the research community’s commitment to climate research that QuikSCAT’s intercalibration mission has continued to receive the highest possible marks for science relevance in the reviews that NASA follows to establish funding priorities for missions like QuikSCAT. The intercalibration mission has enabled research that would not have been possible but for the remarkable stability of the SeaWinds instrument and the exceptional reliability and longevity of the QuikSCAT spacecraft.”

QuikSCAT was originally a recovery mission after the loss of Japan’s Advanced Earth Observing Satellite, which hosted the NASA Scatterometer (NSCAT). The QuikSCAT mission was conceived, developed and launched in less than two years. Ball Aerospace & Technologies Corp. in Boulder, Colorado, built the spacecraft bus, and JPL designed and built the SeaWinds instrument. QuikSCAT was operated by the Laboratory for Atmospheric and Space Physics at the University of Colorado at Boulder.



Images (mentioned), Text, Credits: NASA/JPL/Esprit Smith/NASA’s Earth Science News Team, written by Carol Rasmussen.

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Station Crew Busy With Science After Aborted Launch Ascent

ISS – Expedition 57 Mission patch.

October 12, 2018

Three Expedition 57 crew members are staying busy aboard the International Space Station after the climb to orbit of two crewmates was aborted Thursday morning. American Nick Hague and Russian Alexey Ovchinin made an emergency landing shortly after launch, but are in excellent shape and back in Russia. The trio in orbit is continuing science and maintenance aboard the orbital laboratory.

Image above: North Africa and the Mediterranean Sea are pictured as the International Space Station orbited 254 miles above the African continent. Japan’s Kounotori H-II Transfer Vehicle-7 (HTV-7) is pictured at left attached to the Harmony module. Image Credit: NASA.

NASA astronaut Hague and Roscosmos cosmonaut Ovchinin are safe and returned to Moscow with mission officials after their aborted mission. The Soyuz MS-10 rocket booster experienced a failure about two minutes after launching from the Baikonur Cosmodrome in Kazakhstan. Hague will return to Houston, Texas, on Saturday and Ovchinin will stay in Moscow. Investigations into the cause of the failure are beginning, and the space station international partner agencies are evaluating what changes to the station’s operating plan will need to be adopted.

The three humans still orbiting Earth are safe with plenty of supplies and work to do on orbit. Commander Alexander Gerst and Flight Engineer Serena Auñón-Chancellor started their day measuring how microgravity has impacted their muscles for the Myotones study. They then moved on to researching an ancient technique that may be used for emergency navigation on future space missions.

Serena Auñón-Chancellor is scheduled to talk with two different school groups on Monday and Thursday next week. One of those conversations will involve the flight of Seaman Jr., a plush toy that is part of the National Park Service’s celebration of its the 3,700 mile Lewis and Clark National Historic Trail.

Image above: Flying on the line of the Terrestrial Ecuador, Pacific Ocean, seen by EarthCam on ISS, speed: 27’607 Km/h, altitude: 408,06 Km, image captured by Roland Berga (on Earth in Switzerland) from International Space Station (ISS) using ISS-HD Live application with EarthCam’s from ISS on October 12, 2018 at 18:18 UTC. Image Credits: Aerospace/Roland Berga.

Flight Engineer Sergey Prokopyev maintained life support systems in the Russian segment of the space station. He also updated the station’s inventory system and checked on Russian science experiments.

Related links:

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Ancient technique:

Space Station Research and Technology:

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Images (mentioned), Text, Credits: NASA/Mark Garcia/ Aerospace/Roland Berga.

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Update on the Hubble Space Telescope Safe Mode

NASA – Hubble Space Telescope patch.

Oct. 12, 2018

NASA continues to work toward resuming science operations of the Hubble Space Telescope after the spacecraft entered safe mode due to a failed gyroscope (gyro) on Friday, Oct. 5.

Following the gyro failure, the Hubble operations team turned on a backup gyro on the spacecraft. However, that gyro did not perform as expected, reporting rotation rates that are orders of magnitude higher than they actually are. This past week, tests were conducted to assess the condition of that backup gyro. The tests showed that the gyro is properly tracking Hubble’s movement, but the rates reported are consistently higher than the true rates. This is similar to a speedometer on your car continuously showing that your speed is 100 miles per hour faster than it actually is; it properly shows when your car speeds up or slows down, and by how much, but the actual speed is inaccurate.

When the spacecraft turns across the sky from one target to the next, the gyro is put into a coarser (high) mode. In this high mode it may be possible to subtract out a consistent large offset to get an accurate reading. However, after the large turns are over, the spacecraft attempts to lock onto a target and stay very still. For this activity, the gyro goes into a precision (low) mode to measure very small movements. The extremely high rates currently being reported exceed the upper limit of the gyro in this low mode, preventing the gyro from reporting the spacecraft’s small movements.

NASA’s Hubble Space Telescope. Image Credit: NASA

An anomaly review board that consists of professionals experienced in the manufacturing of such gyros, Hubble operations personnel, flight software engineers and other experts was formed earlier this week to identify the cause of this behavior and determine what solutions can be implemented from the ground to correct or compensate for it.

If the team is successful in solving the problem, Hubble will return to normal, three-gyro operations. If it is not, the spacecraft will be configured for one-gyro operations, which will still provide excellent science well into the 2020s, enabling it to work alongside the James Webb Space Telescope and continue groundbreaking science.

Safe mode places the telescope into a stable configuration that suspends science observations and orients the spacecraft’s solar panels toward the Sun to ensure Hubble’s power requirements are met. The spacecraft remains in this configuration until ground control can correct or compensate for the issue. The rest of the spacecraft and its instruments are still fully functional and are expected to produce excellent science for years to come.

Hubble Space Telescope (HST). Animation Credits: NASA/ESA

A gyro is a device that measures the speed at which the spacecraft is turning, and is needed to help Hubble turn and lock on to new targets. To meet the stringent pointing requirements necessary to study far-off astronomical objects and obtain groundbreaking science data, Hubble’s gyros are extremely accurate. Hubble preferably uses three gyros at any given time to make the observatory as efficient as possible, and would work at slightly lower efficiency on only one gyro.

During Servicing Mission 4 in 2009, astronauts installed six new gyros on Hubble. Three gyros have since failed after achieving or exceeding the average runtime for a Hubble gyro. When fewer than three operational gyros remain, Hubble will continue to make scientific observations in a previously developed and tested mode that uses just one gyro in order to maximize the observatory’s lifetime.

Originally required to last 15 years, Hubble has now been operating for more than 28. The final servicing mission in 2009, expected to extend Hubble’s lifetime an additional 5 years, has now produced more than 9 years of science observations.

Hubble is managed and operated at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Related article:

Hubble in Safe Mode as Gyro Issues are Diagnosed:

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Image (mentioned), Animation (mentioned), Text, Credits: NASA/Felicia Chou.

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