NASA'S Hubble Makes One Millionth Science Observation

Trent Perrotto

Headquarters, Washington

 

Ray Villard

Space Telescope Science Institute, Baltimore

WASHINGTON -- NASA's Hubble Space Telescope crossed another milestone in its space odyssey of exploration and discovery. On Monday, July 4, the Earth-orbiting observatory logged its one millionth science observation during a search for water in an exoplanet's atmosphere 1,000 light-years away.

"For 21 years Hubble has been the premier space science observatory, astounding us with deeply beautiful imagery and enabling ground-breaking science across a wide spectrum of astronomical disciplines," said NASA Administrator Charles Bolden. He piloted the space shuttle mission that carried Hubble to orbit. "The fact that Hubble met this milestone while studying a faraway planet is a remarkable reminder of its strength and legacy."

Although Hubble is best known for its stunning imagery of the cosmos, the millionth observation is a spectroscopic measurement, where light is divided into its component colors. These color patterns can reveal the chemical composition of cosmic sources.

Hubble's millionth exposure is of the planet HAT-P-7b, a gas giant planet larger than Jupiter orbiting a star hotter than our sun. HAT-P-7b, also known as Kepler 2b, has been studied by NASA's planet-hunting Kepler observatory after it was discovered by ground-based observations. Hubble now is being used to analyze the chemical composition of the planet's atmosphere.

"We are looking for the spectral signature of water vapor. This is an extremely precise observation and it will take months of analysis before we have an answer," said Drake Deming of the University of Maryland and NASA's Goddard Space Flight Center in Greenbelt, Md. "Hubble demonstrated it is ideally suited for characterizing the atmospheres of exoplanets, and we are excited to see what this latest targeted world will reveal."

Hubble was launched April 24, 1990, aboard space shuttle's Discovery's STS-31 mission. Its discoveries revolutionized nearly all areas of astronomical research from planetary science to cosmology. The observatory has collected more than 50 terabytes of data to-date. The archive of that data is available to scientists and the public at http://hla.stsci.edu/.

Hubble's odometer reading includes every observation of astronomical targets since its launch and observations used to calibrate its suite of instruments. Hubble made the millionth observation using its Wide Field Camera 3, a visible and infrared light imager with an on-board spectrometer. It was installed by astronauts during the Hubble Servicing Mission 4 in May 2009.

"The Hubble keeps amazing us with groundbreaking science," said Sen. Barbara A. Mikulski, the chairwoman of the Senate Commerce, Justice, Science and Related Agencies Appropriations Subcommittee that funds NASA. "I championed the mission to repair and renew Hubble not just to get one million science observations, but also to inspire millions of children across the planet to become our next generation of stargazers, scientists, astronauts and engineers."

Hubble is a project of international cooperation between NASA and the European Space Agency. Goddard manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy Inc. in Washington.

For more information about Hubble, galleries of videos and images, visit http://www.nasa.gov/hubble and http://hubblesite.org/news/2011/22.

For details about the exoplanet Kepler 2b, including an animation of its orbit, visit http://kepler.nasa.gov/Mission/discoveries/kepler2b/.

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Mission Manager Update: Kepler Spacecraft Status Report

At the May 23 press event, held at the 218th Meeting of the American Astronomical Society in Boston, the team provided a progress report on the mission. This Mission Manager Update will focus on flight segment performance of the Kepler spacecraft. In other words, how is Kepler performing while trailing Earth around the sun?

The health of the spacecraft and photometer, the instrument used to measure changes in the brightness of distant stars, is excellent and has recorded more than two months of routine operations in this quarter. The observing efficiency in Quarter 9, which is April through June 2011, has been above 97 percent due to two very efficient monthly science data downlinks in April and May-- 16.6 hours and 15.2 hours, the quickest yet! Coupled with no unplanned breaks in collecting science data, it has been a strong quarter so far.

The monthly downlinks are planned science breaks where science data collected since the previous monthly contact is retrieved. Any data missed in the previous month’s downlink is retransmitted. Kepler is NASA’s first mission to use Ka band, a microwave band of the electromagnetic spectrum within the 26.5 to 40 GHz range, for routine science data downlinks. Prior to launch, it was estimated that up to 25 percent of each downlink would need to be retransmitted at the next monthly contact. This could be as a result of unforeseen interference with ground-based antennas or the spacecraft during the contact. However, performance of Ka band downlink between the spacecraft and the Deep Space Network ground stations has been excellent. Greater than 99 percent of science data reaches the ground on the first attempt. To ensure no data is left behind, 100 percent of the downlink is collected during the following month’s contact.

Downlinking science and engineering data typically accounts for about six hours of a monthly contact. The remainder of the time is spent collecting calibration data and maneuvering the spacecraft to point the high-gain antenna (HGA) at Earth for the downlink. Once the downlink is complete, the photometer is returned to science attitude, resuming data collection and regular maintenance. For example, during the monthly contact in May, the team completed a file uplink to the spacecraft to mitigate the root causes of the anomalies encountered during Quarter 8 operations.

The duration of the science downlinks will increase over the course of the mission as the range between the spacecraft and Earth increases. Kepler is in a heliocentric orbit, slowly drifting further behind Earth each year as it orbits the sun. As the range increases, a lower downlink rate will need to be configured to maintain the link between the spacecraft and the ground. To date, the downlink rate operates at the maximum Ka band rate of 4.3 Mbps.

Kepler is currently 36.7 million kilometers from Earth. At the end of the nominal 3.5-year mission it will be almost 69 million kilometers away. For a mission extending beyond 3.5 years, the number of stellar targets would either be reduced so there are less data to return or have the same amount of targets and take longer to downlink to compensate for the growth in distance.

Last month, the first reaction wheel passed one billion revolutions. This means the spacecraft is on target to meet the goal of fewer than two billion revolutions during the nominal 3.5-year science mission. Reaction wheels are the primary actuators for controlling the attitude of the spacecraft. The wheels rotate faster or slower to maneuver the spacecraft, or just maintain science attitude, while compensating for external torques like solar wind. The number of revolutions is driven by how much external torque the wheels need to counteract. This will determine the rate at which the wheels change speed, and how long before the reaction control system thrusters are needed to desaturate, or unwind, the wheels. This will determine the maximum speed reached. The latest estimates show the spacecraft is equipped with enough propellant for the thrusters to last for an additional eight years. Two billion revolutions in the 3.5-year mission is a goal and would not limit the spacecraft from continuing to collect data.

While the reaction wheels are the actuators that point the spacecraft, the sensors used while collecting science data are the fine guidance sensors. There are four CCDs, or charged coupled devices similar to those in a digital camera, on the corners of the photometer’s focal plane array. The CCDs take measurements of 40 guide stars while in fine point, the attitude required for collecting science data. The Kepler Science Operations Center (SOC) takes a set of reference pixels from the science CCDs that are collected once per day and monitors the pointing of the focal plane, ensuring the spacecraft is precisely pointed at the stellar targets. The most recent estimate from the SOC shows that while the spacecraft drifted four to five millipixels over the quarter, it is currently less than half of a millipixel away from where it started collecting science this quarter. That means the light from the stars Kepler is monitoring falls on the same part of the science CCDs, which is required to obtain the precision necessary to detect planet transits. A science CCD pixel covers four arcseconds of the field-of-view. The spacecraft is only two milliarcseconds away from where it was pointing at the beginning of the quarter. An arcsecond is 1/3,600 of a degree or 1/1,296,000 of a circle. A change of two milliarcseconds is like looking at a laptop screen in New York City from San Francisco, and after two months the line of sight is now an inch and a half from the center of the screen. That’s impressive staring!

Kepler is performing well and is delivering an abundance of data capturing over 5.5 billion brightness measurements over its first two years of science operations. The galactic stare down continues...

For more information on the progress of the mission and to watch the May 23 press event, see the Kepler at AAS feature http://www.nasa.gov/mission_pages/kepler/news/kepler_May2011_AAS.html.

To view a full image gallery of the Kepler spacecraft, photometer, and electronics, see the Ball Aerospace Kepler Gallery, visit: http://www.ballaerospace.com/gallery/kepler/index.htm.

Michele Johnson, Public Affairs Officer, Kepler Mission

Ames Research Center, Moffett Field, Calif.

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NASA Television Covers Station Cargo Craft Departure And Arrival

Michael Curie

Headquarters, Washington                               

 

Kelly Humphries

Johnson Space Center, Houston

 

HOUSTON -- NASA Television will provide live coverage during a busy International Space Station traffic pattern, when one cargo spacecraft departs and another arrives.

The European Space Agency's "Johannes Kepler" Automated Transfer Vehicle-2 (ATV2) is scheduled to undock from the station's Zvezda service module port at 9:48 a.m. CDT on Monday, June 20, and will burn up in the atmosphere over the Pacific Ocean.

ATV2, the second unpiloted European cargo ship, delivered seven tons of food and supplies and is supporting a series of reboosts to raise the station's orbit. It has been linked to the station since February. NASA TV will incorporate coverage of the undocking into the "ISS Update" hour, which will air at 9:30 a.m. Monday.

The next day, the Russian Progress 43 cargo ship will launch from the Baikonur Cosmodrome in Kazakhstan at 9:38 a.m. (8:38 p.m. Baikonur time), carrying nearly three tons of food, fuel and supplies for the six-person Expedition 28 crew. The launch will be part of the NASA TV "ISS Update" that day, which will air at 9 a.m. NASA TV will provide live coverage of the Progress docking beginning at 11 a.m. on Thursday, June 23.

For NASA TV streaming video, downlink and scheduling information, visit http://www.nasa.gov/ntv.

For International Space Station information, visit

http://www.nasa.gov/station.

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Kepler at AAS

New findings from NASA's Kepler mission were presented at the 218th American Astronomical Society meeting

Kepler-10c and a New Method to Validate Planets

Today the Kepler team is announcing another member of the Kepler-10 family, called Kepler-10c (larger foreground object in the image on this page). It has a radius of 2.2 times that of Earth's, and it orbits the star every 45 days. Both Kepler-10b and 10c would be blistering hot worlds.

Kepler’s Astounding Haul of Multiple Planet Systems

Cambridge, MA — NASA’s Kepler spacecraft is proving itself to be a prolific planet hunter. Within just the first four months of data, astronomers have found evidence for more than 1,200 planetary candidates. Of those, 408 reside in systems containing two or more planets, and most of those look very different than our solar system.

- Harvard Smithsonian Center for Astrophysics Press Release 2011-14 of May 23, 2011

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Mission Manager Update - Another 93 Gigabits of Data Added to the Archive

During a regularly scheduled science data download on Tuesday, April 26, the project team reoriented the Kepler spacecraft to downlink data from its solid-state recorder (SSR). All data collected since March 20 was returned successfully. The Quarter 9, Month 1 science data collection download now is complete.

Communications with Kepler while it is in the science attitude is accomplished using a low gain antenna on the spacecraft that operates on X-band frequency. To return all the science and engineering data that has been stored on the SSR, a high-gain antenna (HGA) operating in Ka-band frequency is used. The HGA must be pointed at Earth to support the high rate downlink (4.3 Mbps). This temporarily prohibits the spacecraft from pointing at the science field-of-view.

The monthly activity includes collection of science calibration data; turning the HGA toward Earth; and, playing back the SSR data - approximately 45 minutes for engineering data and another 5.25 hours for 37 days of science data. The number of days in each month's science set varies a bit due to Deep Space Network, or DSN, availability and other scheduling constraints. A total of 93 gigabits of data was downloaded in approximately six hours before reorienting the spacecraft to science attitude.

In order to return to the fine point attitude control, which is the highest pointing stability and what is required for science, the project team must wait for the spacecraft to return to the thermal condition it was in before the break. When the spacecraft is turned to a different attitude, the sun shines on different parts of the structure, which causes it to warp ever so slightly. This slight warping means that the angle between the star trackers and the telescope line of sight is a bit off. When it's maneuvered back to the science attitude, it takes time to settle back to its original shape. Until the spacecraft has thermally settled, the telescope will not be aligned with its guide stars well enough for us to transition to fine point. This can take eight hours or more. This month's activity went very well, and the total science break, which includes the collection of calibration data, was about 17 hours. The monthly budget is 20 hours.

The data is downloaded via NASA’s DSN operated by the Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology (Caltech) in Pasadena, Calif. From the DSN, the data flows to the Mission Operations Center in Boulder, Colo., and on to the Data Management Center in Baltimore, Md. The raw pixels are archived at the Data Management Center and then transmitted to the Kepler Science Operations Center (SOC) at NASA’s Ames Research Center in Moffett Field, Calif.

The data has arrived at the SOC and will be processed this week.

Kepler is currently 32 million kilometers from Earth, collecting science data at the Spring attitude (the angular orientation of the spacecraft), in its 9th quarter of operations. All subsystems are operating normally. The next download of science data is scheduled for May 25.

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NASA Kepler Reaching into the Stars

We are entering a golden era for "stellar physics" – a term coined to describe research about the formation, evolution, interior and the atmospheres of stars. Thanks to a partnership forged among stellar astrophysics, scientists and NASA’s Kepler Mission, a goldmine of data is now available to support the world's efforts to detect planets in the habitable zone around other stars.

The Kepler photometric data is a measurement of light’s “brightness,” and provides an unprecedented opportunity for the emerging field of asteroseismology, the study of the internal structure of stars by observing minuscule pulsations in the star brightness. Asteroseismic research is giving insights into the fundamental properties of stars, including their mass, size, age and internal structure. Kepler enables studies of a large number of stars representing a broad range of types. This asteroseismic research will substantially improve our understanding of stellar evolution. It also will help determine the properties of stars that have planetary systems studied in the Kepler exoplanet program.

The Kepler Asteroseismic Science Consortium (KASC) pushes the envelope in this field of study. Using the unparalleled precision and quality of Kepler data, the KASC research is contributing to stellar astrophysics in profound ways. The consortium is comprised of more than 400 scientists and is led by the Danish Asteroseismology Centre in the Department of Physics and Astronomy at the University of Aarhus, Denmark.

The KASC recently presented new findings published in three papers in the journal Science. In combination, these latest results illustrate the power of the Kepler Space Telescope to probe the internal structure of distant stars.

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