Mission Manager Updates—2009
Kepler Mission Manager,
NASA Ames Research Center
Since start of Kepler's science data-collection phase, we do a health check of the spacecraft twice a week and download science data once per month. Updates will normally be posted about bi-weekly.
2009 November 23 Mission Manager Update -
Kepler experienced a safe mode event on November 18. A safe mode is a self-protective measure that the spacecraft takes when something unexpected occurs. During safe mode, the spacecraft points the solar panels directly at the sun and begins to slowly rotate about a sun-aligned axis. The spacecraft automatically powered off the photometer and one redundant subsystem as a safety precaution. Engineers immediately began telemetry analysis to determine spacecraft subsystem health, and root cause determination of what triggered the safe mode. This safe mode occurred when the team was preparing to download another month of scientific data from Kepler. The scientific data was not in danger and was downloaded successfully via the NASA Deep Space Network on November 19. Engineers verified nominal performance of all of Kepler’s systems and successfully recovered the vehicle from safe mode. Science data collection was resumed by the evening of November 20.
This was the third Safe mode Kepler has experienced since operations began on May 12, 2009. This Safing event occurred during a planned break in science data collection, causing a minimal delay in return to science operations. The Kepler engineers budget for the potential loss of up to 12 days of science per year from Safing events. While Kepler continues its next 30 days of science data collection, engineers will pore over data to determine the cause of the malfunction. The next download of science data is scheduled for mid-December 2009.
Meanwhile, the Kepler Guest Observer Office is preparing for the next round of community-led science proposals. The Guest Observer Program is an annual opportunity for astronomers outside of the Kepler Team to add sources of interest to the Kepler target list and receive research grants from NASA to exploit those data. The first cycle of Guest Observer proposals yielded a diverse program of galactic and extragalactic experiments which are currently underway. We eagerly await proposals for the next cycle that will continue to expand the scientific impact of the Kepler mission. The deadline for Guest Observer proposals is Jan. 15, 2010, with Notices of Intent due Dec. 4, 2009. Further details are available at our Guest Observer website, http://keplergo.arc.nasa.gov, which we encourage you to explore.
This update's "Meet the Kepler Team" features Charlie Sobeck, Kepler Chief Engineer at NASA Ames Research Center.
2009 November 5 Mission Manager Update - Kepler completed another science data download over October 18-19. In this download, a month’s worth of science data was transmitted through the NASA Deep Space Network and into the Science Operations Center at Ames Research Center. After the download was complete, the Kepler spacecraft was returned to its science collection attitude and another cycle of science data collection began.
While the Kepler spacecraft continues in its orbit, and collecting science data, the Kepler team at the Ames Research Center continues its work on the science data processing pipeline software. Their work has allowed for the publication of Kepler’s first science discovery, the occultation associated with previously discovered transiting exoplanet HAT-P7-B. This discovery showed the precision of the Kepler instrument and its ability to detect signals whose sizes are consistent with the transit of an Earth-size planet. Additionally, results from data taken since operations began on May 12 have allowed the Kepler Science Team to select a number of planetary candidates for follow-up observation and potential confirmation. It is expected that confirmation of a number of planets will be announced by NASA in conjunction with the January 2010 American Astronomical Society (AAS) meeting in Washington DC.
Finding Earth-size planets requires detecting very faint transit signals against the inherent background noise of the measurements. Kepler noise sources come in three broad categories: stellar variability, random noise, and systematic noise.
Stellar variability is the natural fluctuation in the brightness of the stars themselves. Some stars are much more variable than others, and so the Kepler team must examine the light curves and determine which stars are suitably quiet for finding planets. Stars that are too noisy can be replaced on the target list by other stars from the input catalog.
Random noise is present in all measurements and cannot be calibrated out. Therefore, strict requirements were placed on the design of Kepler’s spacecraft systems to limit random noise to a low level. Measurements taken in space confirm that Kepler meets its random noise requirements.
Systematic noise results from the imperfect nature of any measuring device. It represents the instrument’s “finger print” placed upon the measurement, and must be calibrated out of the data in post-processing on the ground. Because systematic noise depends on the specific characteristics of the instrument, the best calibration requires that the noise sources be characterized and modeled based on measurements made in space. The Kepler team has been developing the ground software to calibrate out the various systematic noise sources since launch, and this work will continue for a number of months. As each source of systematic noise is calibrated, fainter transit signals can be detected. Data collected from the spacecraft will be continually reprocessed as the ground software matures, revealing smaller and smaller planets. This is a normal process and has been part of the Kepler plan since before launch. Fortunately for Kepler, the worst sources of systematic noise affect only a small portion of the field of view, so the majority of the field of view will be calibrated earlier, enabling small planets to be detected sooner.
Detecting planets requires at least three transits, which occur only once per orbit. For Earth-like planets orbiting in the habitable zones of sun-like stars it will take three to four years to collect three transits, and so these discoveries are several years in the future. The habitable zones around stars smaller than our sun involve shorter period orbits, so it is likely that Earth-size planets will be found around such low mass stars sooner.
While operations of the Kepler spacecraft continue, the Kepler Science Team is preparing for the January AAS meeting a number of papers and presentations on Kepler and its early results. Also in January, special issues of both Science Magazine and the Astrophysical Journal will publish 3 overview papers in the former and several papers discussing technical aspects of the Mission in the latter journal. As the AAS draws closer, the Kepler project is delighted to report that some of Kepler’s data is closer to being made public. Data collected by the Kepler Mission during commissioning, and during the first six weeks of the science operations, have now been processed and sent to the archive at the Space Telescope Science Institute in Baltimore, MD. From there the data will be available to the Science Team members for their continued investigations. This early data will be released to the public in June 2010.
Note: MAST is already publicizing the release of the dropped target data and it is possible to download light curves (as of Nov 4).
2009 October 14 Mission Manager Update - It has now been five months since Kepler science operations began. The Kepler spacecraft continues in its drift-away, heliocentric orbit, and continues in its science data collecting attitude. The Kepler team is approaching another monthly download of science data. The next scheduled download is planned for Oct. 17-19, 2009. Further analysis had been completed on the Safing events that Kepler experienced on June 15, 2009, and July 2, 2009. The cause has been further isolated to a low voltage power supply, whose upsets cause the central RAD750 processor to reset. The resets were not caused by any problem with the RAD750 processor unit itself.
Last week, the team performed two semi-weekly spacecraft contacts. This “engineering” contact utilizes the vehicle’s X-Band transmitter and the omni-directional antennas to give us a relatively low bandwidth connection (typically ranging from 2 to 8 kbps). Although insufficient to downlink the extensive science data being collected and stored onboard, this connection has the benefit that we do not have to leave the science attitude and hence can continue to collect science data as the operations team checks out the vehicle. These contacts typically last about 8 hours, during which time onboard logs are downlinked, along with a small portion of the science targets that have been chosen to give us a quick look at the instrument performance in case any adjustments need to be made. These contacts also give us the opportunity to upload new command sequences, software patches or parameter updates, if required.
This update's "Meet the Kepler Team" features Bill Wohler, Kepler Science Operations Center (SOC) Sr. Principal Software Engineer at NASA Ames Research Center.
2009 September 22 Mission Manager Update - Kepler is approximately 18 million kilometers (11 million miles) from Earth, and continuing its drift-away orbit. All systems are operating normally. Last week, the Kepler project team completed another download of science data, and, in conjunction, a quarterly roll of the spacecraft.
About every 90 days, the team needs to roll the spacecraft about its line-of-sight, to realign the solar panels to the sun for the next season. Unlike the Earth, Kepler does not spin about its axis, so if we do not roll it occasionally, it would show a different side to the sun as it completes its orbit. We perform this maneuver four times a year, hence it is referred to as a quarterly roll.
Last week's operation was the second quarterly roll for Kepler since start of mission. The process began with the pausing of science data collection. The team then then turned the spacecraft so the main antenna pointed toward the Earth. After locking up on the Kepler high-gain antenna with the NASA Deep Space Network, the team downloaded all the data acquired over the previous month. After completion of the science data download, the team uploaded a few parameters and commands, and then turned the spacecraft back to the monitored star-field, but this time with the whole spacecraft rotated 90 degrees from where it was at the start.
After some calibration, data was taken and science observations began again for the next month's set of data. This whole process took only 41 hours, part of which is spent checking on pointing alignment and ensuring the spacecraft is thermally stable after these maneuvers. This data download was about 93 gigabits in size.
The science data are now in the hands of the Kepler Science Operations Center at NASA’s Ames Research Center, Moffett Field, Calif., where scientists and engineers are engaged in detailed analysis. The next scheduled science data download is October 17-18.
Editor’s note: The first set of Kepler information is now available to the public at The Multimission Archive at STScI (MAST) and may be viewed at:
MAST supports a variety of astronomical data archives, with a primary focus on scientifically related data sets in the optical, ultraviolet, and near-infrared parts of the spectrum. See http://archive.stsci.edu/missions.html for a full list of the mission, survey, and catalog data distributed by MAST. MAST is a component of NASA's distributed Space Science Data Services (SSDS).
This update's "Meet the Kepler Team" features Justin Pane, Kepler Contracting Officer at NASA Ames Research Center.
Distance to Kepler spacecraft Sep 22:
about 46 times the average Earth-Moon distance.
2009 September 4 Mission Manager Update - As it nears 11,000,000 miles distance from Earth, the Kepler spacecraft continues to scan the Milky Way galaxy, near the Cygnus constellation, for Earth-sized planets . The spacecraft subsystems are performing nominally, as the science team and engineers are preparing for upcoming events. Scheduled for September 16-20 are another science data download and a quarterly roll of the spacecraft. Similar to the quarterly roll accomplished in late June, this activity keeps Kepler's solar arrays optimally pointed to the sun for power generation. Meanwhile, scientists are continuing to process science data from previous downloads. Engineers have continued to make progress in determining the root cause of the two safing events that Kepler experienced on June 15 and July 2. Radiation testing confirmed the susceptibility of a circuit, in the spacecraft's RAD750 processor, to single-event-upsets, as a credible root cause. The single-event-upset of the circuit would cause the RAD750 to execute a power-on reset, causing the spacecraft to enter a Safe mode. Mitigation actions are being considered for implementation to minimize the impact of any future safing events.
This update's "Meet the Kepler Team" features Jon Jenkins, Analysis Lead (Co-Investigator).
Distance to Kepler spacecraft Sep 4 is
nearly 46 times the average Earth-Moon distance.
2009 August 21 Mission Manager Update - Kepler is over 10,000,000 miles from Earth and continues in its drift away, heliocentric orbit. The Kepler team has just completed another science data download from the spacecraft. The operation involved all of the NASA Deep Space Network sites. Science data collected since early July by Kepler were included in the download. This was also the first time that the Canberra Deep Space Network was used for a science data download since Kepler science operations began on May 12, 2009. Additionally, another Kepler first was achieved in this science data download. The Australian Telescope Compact Array (ATCA) supported Kepler in a shadow-track mode, while the Canberra Deep Space Network site was supporting science data download operations. The ATCA could be used as a possible back-up to the Canberra site in the future for Kepler science operations.
Investigation into Kepler's two safing events is ongoing. Engineers have determined that the safing events were caused by resets of the Kepler RAD750 main processor. Engineers continue to sift through data and conduct additional tests on similar RAD750 processor components to further isolate the root cause of the safing events. Since the July 2, 2009 safing event, no further safing modes have occurred on Kepler. We have continued daily contacts with the spacecraft to extract additional diagnostic telemetry to support root cause determination for the safing events. The team plans to continue daily contacts through the next science data download, which is scheduled for September 17-18, 2009. The next science data download also coincides with a quarterly roll operation for Kepler. Like the quarterly roll conducted in June 2009, the spacecraft will be rolled ninety-degrees to keep solar arrays normal to the sun. This will ensure the spacecraft solar arrays receive proper illumination for power generation.
A safe mode is a programmed precautionary response that spacecraft use when they sense a condition for which they do not know a more specific response. During safe mode events, spacecraft stop non-critical activities and await further instructions from their mission team.
Today we are introducing a new feature called “Meet the Team” to acquaint our readers with members of the Kepler Mission Team. This update features David Koch, Kepler's Deputy PI.
2009 July 23 Mission Manager Update - Kepler remains in its science attitude and Earth-trailing, helio-centric orbit. The spacecraft is nearing 9,000,000 miles distance from Earth. All Kepler systems are now nominal as it continues to survey its target stars, looking for Earth-sized planets. The last science data downlink occurred on June 18-19, 2009. That downlink included observations of more than 145,000 stars continuously monitored by Kepler for more than 30 days. This downlink comprised about 50 gigabits of data that were processed through the Kepler Science Operations Center at NASA’s Ames Research Center. The processed data were presented to the Kepler Science Team for its review and analyses. The analyses will continue for some time as the project prepares for the next science data download.
No additional safe modes have occurred since the July 2, 2009 safing event. Since the June and July safing events, engineers have continued analyses of Kepler's telemetry data to ascertain their root cause,which appear to be identical. As a precaution, and to gain more information to aid in root-cause determination, engineers have scheduled additional contacts with Kepler. Daily contacts with Kepler began on July 3, 2009, and will continue for the near future. These daily contacts are used to extract additional diagnostic telemetry information, and serve to react to any possible safe mode events more quickly. Given the break in science that occurred on July 2, 2009 by the safing event, the Kepler team determined a downlink of science data scheduled for July 20, 2009 could be delayed to August 20, 2009.
A safe mode is a programmed precautionary response that spacecraft use when they sense a condition for which they do not know a more specific response. During safe mode events, spacecraft stop non-critical activities and await further instructions from their mission team.
2009 July 7 Mission Manager Update - On July 4, Kepler passed a point 12,500,000 kilometers (7,767,140 miles) from Earth. In a regularly scheduled communication with Kepler on July 2, engineers determined the spacecraft had entered safe mode. Safe mode is a self-protective measure that a spacecraft takes when a malfunction occurs. Engineers diagnosed the health and safety of the spacecraft subsystems. All subsystems were found to be normal, with the photometer turned off (the photometer is automatically turned off in a safe mode event). After downloading engineering health and status files, the Kepler project team continued taking steps to return the spacecraft to science operations. Science data collected since June 19 were downloaded to ground controllers, the photometer was powered back on, and Kepler was reoriented back to its science data collecting attitude. By late July 3, Kepler had returned to normal science operations.
Engineers determined that this event was caused by a processor reset, as it was with a similar safe mode event on June 15. They continue to evaluate data from both events to determine their root cause.
2009 June 19 Kepler Mission Manager Update - Kepler is more than 10,700,000 kilometers (about 6,600,00 miles) from Earth and continues its planned drift-away orbit. Since May 12, 2009, Kepler has been observing its target region near the Cygnus constellation. Today, data collected continuously since science operations began on May 12, 2009 were downloaded to the Kepler Science Operations Center at Ames Research Center, Moffett Field, Calif. The data were collected from observing over 145,000 stars simultaneously. Scientists will begin in earnest the analysis of this data to search for other Earth-size planets. Engineers also completed Kepler's planned quarterly roll. This roll will ensure that Kepler's solar arrays are kept optimally positioned with respect to our sun, to ensure proper power generation, for the next three months. Both the science data download, and the quarterly roll, are Kepler "firsts" in its planned three-and-a-half-year mission.
On June 15, 2009, Kepler entered safe mode, a protocol executed by the spacecraft as a precautionary safety feature. In this case, the safe mode entry was caused by a fault in part of the spacecraft processor. Upon detection of the entry into safe mode, engineers began anomaly response procedures to determine spacecraft health and status, cause of the fault, and recovery. Engineers determined the spacecraft's stored science data was safe. The fault caused the Kepler photometer to turn off. Further analysis indicated the Kepler subsystems were not endangered by the fault. Engineers re-initialized the photometer, downlinked the science data, performed the quarterly roll, and returned the spacecraft to its mission. Analysis will continue on spacecraft telemetry files to better understand the root cause of the safe-mode event. The mission baseline allows for 12 days per year for potential safe-mode events such as this one. This particular event consumed about one-and-a-half days of what would have been time collecting science data. In mission dress rehearsals prior to launch, the Kepler team practiced responses to non-nominal conditions, like safe-mode events and spacecraft malfunctions. Thanks to this practice, the team responded effectively and efficiently to restore Kepler to its nominal operational status. Twice-per-week routine contacts with the Kepler spacecraft will resume, as Kepler collects another 30 days of science data in its hunt for Earth-like planets. The next science data download will occur in late July.
2009 June 9 Kepler Mission Manager Update - Kepler is nearing 10 million kilometers from Earth, and will pass that mark on June 12. The spacecraft remains in its stable science attitude, observing its target stars.
The team is preparing for the upcoming science data downlink and quarterly roll maneuver that will occur around June 18. This contact with Kepler is a relatively long contact, and will involve two ground stations from the Deep Space Network (DSN). The spacecraft will be rolled 90 degrees to keep the solar panels toward the sun. This contact will downlink data, collected since May 12, 2009 on over 145,000 stars, through the NASA DSN, to the Ames Research Center's Kepler Science Operations Center. After the science data downlink is complete, new target tables will be loaded onto the spacecraft. Because the photometer's detectors are also rolled with the spacecraft, the detectors have to be given updated target parameters, to observe the same stars, since the spacecraft field-of-view rotates 90 degrees. The science office recently completed the new target tables in anticipation of the June 18, 2009 spacecraft contact.
During nominal operations, the spacecraft is contacted twice weekly to evaluate its state-of-health. Once per month, Kepler's science data is downlinked to the ground system. And, once per quarter, the spacecraft will be commanded to execute the roll maneuver to ensure proper illumination of Kepler's solar arrays and power generation.
During Kepler's commissioning phase -- which concluded successfully on May 12, 2009 -- nearly ten days of calibration data were collected on 53,000 stars. As reported in the last update, analysis of this data showed a very high level of precision and the presence of many eclipsing binary stars and variable stars.
2009 May 29 Kepler Mission Manager Update - Kepler remains safe and stable in its "drift-away" heliocentric orbit. The space-craft is over 8.4 million kilometers from Earth. Kepler has been collecting science data since 12 May. The operations team has had nearly daily contacts using the Deep Space Network to check the spacecraft health. Science data collection is, by design, a very quiet period as the scientists want the spacecraft as stable as possible. Other than the continual collection of science data with Kepler's photometer, the only activities that occur on the spacecraft, on a regular basis, are reaction wheel desaturations. These desaturations occur about every 3 days.
The orientation of the spacecraft (keeping the telescope pointed at the science field of view) is controlled by reaction wheels which slowly spin up to counter pressure from solar wind. Before any given wheels spin too fast, thrusters are fired to negate the momentum imparted to the spacecraft from the spin-up of the reaction wheels. The reaction wheel speeds are returned to near-zero, and the cycle begins again. We have loaded a command sequence on-board the spacecraft to execute these desaturations.
Meanwhile, scientists at NASA Ames Research Center are continuing their analysis of the instrument calibration data taken during Kepler's commissioning phase. The data are of very high quality and the scientists are very pleased with the precision of the data. Hundreds of eclipsing binaries and variable stars were seen in this data.
Jim Fanson, Kepler
JPL Mission Manager
(through 2009 May 15)
2009 May 14 Mission Manager Update - Following a successful readiness review, Kepler began its search for planets around other stars at 5:01 p.m. Pacific Time (8:01 p.m. Eastern Time) on May 12, 2009. The first of the science data are scheduled to be sent down to Earth on June 18, at which point analysis of the data by the science team will commence. While it will take years to discover any Earth-size planets orbiting in the habitable zones of stars (regions where temperatures are right for liquid water), we expect to confirm fairly quickly the three planets known to transit, or cross in front of, their stars in the Kepler field of view. In the months ahead, we expect to begin detecting large planets that orbit their stars closely.
This activity concludes the commissioning phase of the project, and this is the last mission update I will be writing. Going forward during mission operations, updates will be provided by Roger Hunter, who will become the Kepler Mission Manager at NASA Ames Research Center, Moffett Field, Calif., when management responsibility is transferred from JPL in the weeks ahead. It has been a pleasure for me to share these updates with you as we embark on this historic mission of discovery.
2009 May 13 KEPLER MISSION STATUS REPORT - 2009-084 - Let the Planet Hunt Begin. Excerpt: NASA's Kepler spacecraft has begun its search for other Earth-like worlds. The mission, which launched from Cape Canaveral, Fla., on March 6, will spend the next three-and-a-half years staring at more than 100,000 stars for telltale signs of planets. Kepler has the unique ability to find planets as small as Earth that orbit sun-like stars at distances where temperatures are right for possible lakes and oceans. "Now the fun begins," said William Borucki, Kepler science principal investigator at NASA's Ames Research Center, Moffett Field, Calif. "We are all really excited to start sorting through the data and discovering the planets." Scientists and engineers have spent the last two months checking out and calibrating the Kepler spacecraft. Data have been collected to characterize the imaging performance as well as the noise level in the measurement electronics. The scientists have constructed the list of targets for the start of the planet search, and this information has been loaded onto the spacecraft....
The mission's first finds are expected to be large, gas planets situated close to their stars. Such discoveries could be announced as early as next year. See Full Report.
2009 May 7 Mission Manager Update - Kepler is now more than six million kilometers (3.7 million miles) from Earth, with a round-trip light time -- the time it takes a command to reach the spacecraft and a response to return to Earth -- of 40 seconds. The final performance data are being collected to assess the sensitivity of the science instrument. This will determine how well Kepler will be able to measure the transits of small planets like Earth.
The operations team no longer communicates around the clock with Kepler; contact through NASA's Deep Space Network is reduced to about 18 hours per day and will soon drop to about 6 hours per day when science observations begin. This is a gradual transition to the mode of operation planned for the remainder of the mission, when communication will occur only twice per week. The project will convene a science operations readiness review on Monday, May 11, to determine if the team is ready to commence science data collection.
2009 May 1 Mission Manager Update - Kepler's calibration data collection is drawing to a close. Several hundred data sets have been acquired to characterize and map the optical and noise performance of the telescope and the electronics for the focal plane array (the area where light is focused). The data sets are now being analyzed on the ground. Optimally shaped "windows" of pixels will be defined for each of the more than 100,000 target stars and a table of these pixels uploaded to the spacecraft. These are the pixels that will ultimately help the science team find planets -- the pixels will be downlinked to Earth and used to construct light curves, or measurements of brightness over time, for each star.
After science observations begin, the data analysis "pipeline" at the Science Operations Center at NASA's Ames Research Center in Moffett Field, Calif., will process the light curves to identify "threshold crossing events," which is the first step in identifying potential transiting planets. Various tests will be applied to these events to weed out false indications. Once confidence is built for candidate transits, observations by ground-based telescopes will be performed to further rule out phenomena that can masquerade as transiting planets.
- 2009 May 01 14:00 UTC - Distance to Kepler: 5,382,000 km; 3,344,000 mi; 0.036 AU; 14.00 times the distance to the Moon.
- 2009 April 30 14:00 UTC - Distance to Kepler: 5,277,000 km; 3,279,000 mi; 0.035 AU; 13.73 times the distance to the Moon.
- 2009 April 29 14:00 UTC - Distance to Kepler: 5,173,000 km; 3,214,000 mi; 0.035 AU; 13.46 times the distance to the Moon.
- 2009 April 28 14:00 UTC - Distance to Kepler: 5,069,000 km; 3,150,000 mi; 0.034 AU; 13.19 times the distance to the Moon.
- 2009 April 27 14:00 UTC - Distance to Kepler: 4,966,000 km; 3,086,000 mi; 0.033 AU; 12.92 times the distance to the Moon.
- 2009 April 26 14:00 UTC - Distance to Kepler: 4,863,000 km; 3,022,000 mi; 0.033 AU; 12.65 times the distance to the Moon.
- 2009 April 25 14:00 UTC - Distance to Kepler: 4,762,000 km; 2,959,000 mi; 0.032 AU; 12.39 times the distance to the Moon.
- 2009 April 24 14:00 UTC - Distance to Kepler: 4,661,000 km; 2,896,000 mi; 0.031 AU; 12.13 times the distance to the Moon.
2009 April 23 Mission Manager Update - The Kepler telescope's focus has been successfully optimized. This involved moving the primary mirror of the telescope toward the focal plane array, the area where light is focused, by 40 microns (1.6 thousandths of an inch) and tilting it by 0.0072 degrees. Various other calibrations are underway, including: detailed measurement of star images formed by the telescope at various locations on the focal plane; determination of the exact sky coordinates of every one of the camera's 95 million pixels, and mapping of "ghost" images, which result when the light from bright stars reflects off the front of the camera's charge-coupled devices (CCDs), bounces off lenses inside the telescope, and winds up back on the CCDs in another location.
2009 April 23 14:00 UTC - Distance to Kepler: 4,561,000 km; 2,834,000 mi; 0.03 AU; 11.87 times the distance to the Moon.
- 2009 April 22 14:00 UTC - Distance to Kepler: 4,461,000 km; 2,772,000 mi; 0.03 AU; 11.61 times the distance to the Moon.
- 2009 April 21 14:00 UTC - Distance to Kepler: 4,363,000 km; 2,711,000 mi; 0.029 AU; 11.35 times the distance to the Moon.
2009 April 20 Mission Manager Update - The Kepler science team has decided that further refinement of the telescope's focus would significantly improve the mission's science return. The project is therefore proceeding with these adjustments. The telescope's 1.4-meter (55-inch) primary mirror rests on three displacement actuators, much like a three-legged stool. The actuators can be commanded to extend or contract in tiny steps to adjust the mirror in tip, tilt and piston. This adjusts the position of the optical focal surface, the area where light is first focused, relative to the focal plane array, where the imaging detectors are located. An optimized focus of the telescope would make the image quality more uniform across the field of view and minimize the number of imaging pixels required to measure each target star. This would permit more stars to be monitored with less measurement noise, and result in the planet search being more sensitive to smaller planets.
2009 April 20 14:00 UTC - Distance to Kepler: 4,265,000 km; 2,651,000 mi; 0.029 AU; 11.10 times the distance to the Moon.
- 2009 April 19 14:00 UTC - Distance to Kepler: 4,169,000 km; 2,590,000 mi; 0.028 AU; 10.85 times the distance to the Moon.
- 2009 April 18 14:00 UTC - Distance to Kepler: 4,073,000 km; 2,531,000 mi; 0.027 AU; 10.60 times the distance to the Moon.
- 2009 April 17 14:00 UTC - Distance to Kepler: 3,978,000 km; 2,472,000 mi; 0.027 AU; 10.35 times the distance to the Moon.
2009 April 16 NEWS RELEASE: 2009-067 - NASA'S KEPLER CAPTURES FIRST VIEWS OF PLANET-HUNTING TERRITORY
2009 April 16 Mission Manager Update - Kepler's "first light" image taken the day after cover release is now available to the public. The image shows a glittering array of millions of stars stretching across the field of view. Also in the field are star clusters, background galaxies beyond the Milky Way and three stars that are known to have "hot Jupiters" orbiting them. Kepler will observe these stars for an early confirmation of the planet detection capability of the analysis software to be used on all of Kepler's target stars.
Analysis of the images taken over the past several days shows that the telescope is well within the focus requirements levied on the instrument. The data were taken under stable temperature conditions and with the spacecraft in the highest pointing stability mode, called fine point. Engineers are now working with the science team to determine whether optimizing the focus further would provide a significant improvement in science return. If so, the 1.4-meter (55-inch) primary mirror assembly will be adjusted to fine-tune the alignment.
2009 April 13 Mission Manager Update - Up until a few days ago, NASA's Deep Space Network stations have had their Ka-band radio receivers cross polarized to the spacecraft radio transmitter. Just like your polarized sunglasses reduce glare from the sun, the cross polarized radio configuration reduces the strength of the signal from Kepler, which otherwise would have damaged the radio receivers at the ground stations. Kepler is now 3.6 million kilometers (2.2 million miles) from Earth, far enough that the cross polarization is no longer necessary.
The "first light" images taken by Kepler's photometer following the release of the dust cover are now on the ground and being processed for release. These data were taken when the vehicle was not at "fine point," or as stabilized on the sky as it soon will be. The photometer was also cooling down to operational temperature when the first light images were taken. Now that the telescope temperatures have stabilized, engineers will bring the vehicle to fine-point control, and take a series of images to measure the state of the optical alignment and determine if any adjustments to focus are necessary.
- 2009 April 13 14:00 UTC - Distance to Kepler: 3,605,000 km; 2,240,000 mi; 0.024 AU; 9.38 times the distance to the Moon.
- 2009 April 12 14:00 UTC - Distance to Kepler: 3,514,000 km; 2,184,000 mi; 0.023 AU; 9.14 times the distance to the Moon.
- 2009 April 11 14:00 UTC - Distance to Kepler: 3,423,000 km; 2,127,000 mi; 0.023 AU; 8.90 times the distance to the Moon.
- 2009 April 10 14:00 UTC - Distance to Kepler: 3,333,000 km; 2,071,000 mi; 0.022 AU; 8.67 times the distance to the Moon.
- 2009 April 9 14:00 UTC - Distance to Kepler: 3,243,000 km; 2,015,000 mi; 0.022 AU; 8.44 times the distance to the Moon.
2009 April 8 Mission Manager Update - The dust cover was successfully jettisoned from the front of the telescope last evening at about 7:18 p.m. PDT. Everything went according to prediction, with the vehicle experiencing a slight push to one side. Kepler's attitude control system easily responded to the movement, steering the spacecraft back to its original position.
Starlight was seen in all four of the fine guidance sensors on the corners of the photometer focal plane (the area where light is focused). The spacecraft was maneuvered to the science attitude, or the position where it will collect science data. It will collect images as the temperatures drop to operational range. The next several days will be spent calibrating the alignment of the fine guidance sensors with the spacecraft star trackers, and achieving fine point using the fine guidance sensors. This will enable the spacecraft to stabilize the line of sight at levels similar to the performance of NASA's Hubble Space Telescope.
April 8 14:00 UTC - Distance to Kepler: 3,153,000 km; 1,959,000 mi; 0.021 AU; 8.20 times the distance to the Moon.
2009 April 7 NEWS RELEASE: 2009-065 - DUST COVER JETTISONED FROM NASA'S KEPLER TELESCOPE
This artist's animation illustrates ejection of the dust cover
2009 April 7 - Mission Manager Update, April 7, 2009 - All of the technical and programmatic reviews leading to the release of the dust cover from Kepler are now successfully completed. This has resulted in formal approval from NASA Headquarters to release the cover.
14:00 UTC - Distance to Kepler: 3,064,000 km; 1,904,000 mi; 0.02 AU; 7.97 times the distance to the Moon.
The project team will spend the day today ensuring that all final
planned work is complete and that no new issues have arisen following the formal reviews that have been convened. If everything checks out, the team will begin the procedure to release the cover, which will occur no earlier than about 6:30 p.m. Pacific Time this evening (April 7), with a backup opportunity tomorrow evening.
The spacecraft will be maneuvered into the proper orientation so that the cover, when released, will enter an orbit that will never take it into the field of view of the telescope. When this maneuver is complete, reaction control thruster firings will remove momentum stored in the reaction wheels. This will reduce the wheel speeds to a low level so that they will be able to absorb the momentum imparted when the cover is released.
NASA's Deep Space Network will establish communication with the spacecraft using three large communication antennas in Goldstone, Calif., and Madrid, Spain. The navigation team will prepare to track the motion of the spacecraft using radio-frequency Doppler shifts. The operations team will then send a command to the spacecraft to send a current pulse through a burn-wire in the cover latch release mechanism, and the cover will spring free of the spacecraft. Telemetry from the spacecraft will independently confirm the motion of the cover. At that point, starlight
will enter the telescope for the first time, and engineers will begin the process of evaluating the star images and collecting further calibration data.
2009 April 6 14:00 UTC - Distance to Kepler: 2,975,000 km; 1,849,000 mi; 0.02 AU; 7.74 times the distance to the Moon.
2009 April 5 14:00 UTC - Distance to Kepler: 2,887,000 km; 1,794,000 mi; 0.019 AU; 7.51 times the distance to the Moon.
2009 April 4 14:00 UTC - Distance to Kepler: 2,799,000 km; 1,739,000 mi; 0.019 AU; 7.28 times the distance to the Moon.
2009 April 3 14:00 UTC - Distance to Kepler: 2,711,000 km; 1,684,000 mi; 0.018 AU; 7.05 times the distance to the Moon.
2009 April 2 Mission Manager Update - Flight controllers have transitioned Kepler out of its low-activity safe mode and have powered on its main instrument, the photometer. The spacecraft is in what is called "standby
attitude" with the telescope pointed at the ecliptic North pole. Data will be collected from the photometer over the many hours it will take to stabilize the instrument at its operational temperature. The technical and programmatic reviews leading to dust-cover release are currently scheduled to be completed on Monday, April 6. Dust-cover release is scheduled to occur not earlier than Tuesday evening, April 7.
Distance to Kepler on April 2, 14:00 UTC : 2,623,000 km; 1,630,000 mi; 0.018 AU; 6.82 times the distance to the Moon.
2009 April 1 14:00 UTC - Distance to Kepler: 2,535,000 km; 1,576,000 mi; 0.017 AU; 6.59 times the distance to the Moon.
2009 March 31 14:00 UTC - Distance to Kepler: 2,448,000 km; 1,521,000 mi; 0.016 AU; 6.37 times the distance to the Moon.
2009 March 30. Mission Manager Update - Engineers have determined the cause of Kepler's entry into limited safe mode last week, and are preparing to return the spacecraft to normal operations. In order for Kepler to know where it is in space, and to know where to point its high-gain antenna toward Earth, the spacecraft maintains information about its position, called a state vector, which updates ten times per second. Every few days, navigators on the ground update their knowledge of Kepler's actual orbit, and ground controllers upload a new state vector to the spacecraft. Engineers have concluded that, if the new state vector's start time is a multiple of 1,000 seconds from the start time of the previous vector, a momentary glitch occurs in the calculated spacecraft attitude. Even though this only lasts for one-tenth of a second, the spacecraft senses something it didn't expect and responds by pointing its solar arrays directly at the sun and awaiting further instructions from Earth. It will take a few days to ensure that everything is ready to proceed with commissioning, the next major step being release of the telescope's dust cover. March 30 14:00 UTC - Distance to Kepler: 2,362,000 km; 1,467,000 mi; 0.016 AU; 6.14 times the distance to the Moon.
2009 March 29 14:00 UTC - Distance to Kepler: 2,275,000 km; 1,414,000 mi; 0.015 AU; 5.92 times the distance to the Moon.
2009 March 28 14:00 UTC - Distance to Kepler: 2,189,000 km; 1,360,000 mi; 0.015 AU; 5.69 times the distance to the Moon.
2009 March 27 14:00 UTC - Distance to Kepler: 2,103,000 km; 1,307,000 mi; 0.014 AU; 5.47 times the distance to the Moon.
2009 March 26 Mission Manager Update - Scientists have analyzed "dark" calibration data taken by Kepler with its dust cover on, and have concluded that the telescope's focal-plane array, the area where light is focused, is behaving as expected. No additional dark calibration is required. The results agree with ground tests performed in a simulated space environment, once the effect of cosmic rays and solar protons are taken into account. Cosmic rays and solar protons are largely blocked from reaching Earth's surface by our planet’s atmosphere and magnetic field, and therefore don’t show up in the ground-test data. The next major step in commissioning is the release of the dust cover, which will permit starlight to enter the telescope.
On Monday, March 23, Kepler entered a limited-activity safe mode. Safe mode involves the spacecraft automatically pointing its solar arrays directly at the sun, powering off its photometer instrument, and rotating very slowly about the spacecraft-sun line. Engineers have full control of the spacecraft and are investigating the possible cause of its entry into safe mode. Once a better understanding of the cause is reached, the operations team will prepare the spacecraft to resume commissioning activities.
Distance to Kepler, 2009 March 26 14:00 UTC: 2,017,000 km; 1,254,000 mi; 0.013 AU; 5.25 times the distance to the Moon.
2009 March 25 14:00 UTC - Distance to Kepler: 1,932,000 km; 1,201,000 mi; 0.013 AU; 5.03 times the distance to the Moon.
2009 March 24 14:00 UTC - Distance to Kepler: 1,847,000 km; 1,148,000 mi; 0.012 AU; 4.80 times the distance to the Moon.
2009 March 23 14:00 UTC - Distance to Kepler: 1,762,000 km; 1,095,000 mi; 0.012 AU; 4.58 times the distance to the Moon.
2009 March 22 14:00 UTC - Distance to Kepler: 1,677,000 km; 1,042,000 mi; 0.011 AU;4.36 times the distance to the Moon.
2009 March 21 14:00 UTC - Distance to Kepler: 1,591,000 km; 988,800 mi; 0.011 AU; 4.14 times the distance to the Moon.
2009 March 20 Mission Manager Update - Kepler is now 1.5 million kilometers (930,000 miles) from Earth. At that distance it takes a total of 10 seconds for a command sent from Earth, traveling at the speed of light, to reach the spacecraft and for a reply to arrive back at Earth. Flight controllers call this the "round-trip light time," and take this time delay into account when commanding the spacecraft.
Scientists are analyzing the first calibration data collected when the spacecraft's photometer was positioned as far away from the sun as possible, while engineers are continuing to collect data at various temperatures. With the cover still closed over the front of the telescope, most components are a bit warmer than they will be when the cover is released. The Schmidt corrector, a 1-meter-diameter (39-inch) slightly non-spherical lens at the front of the telescope, is currently at a temperature of -30 degrees Celsius (-22 Fahrenheit), and the primary mirror at the back of the telescope is at -11 degrees Celsius (12.2 degrees Fahrenheit). The focal-plane array of charge-coupled devices (CCDs) is being maintained at its operational temperature of -85 degrees Celsius (-121 degrees Fahrenheit) to minimize detector noise. Commissioning activities continue to go smoothly, and the vehicle is performing well.
2009 March 19 14:00 UTC - Distance to Kepler:
1,419,000 km; 881,900 mi; 0.009 AU;
3.69 times the distance to the Moon.
2009 March 18 Mission Manager Update - Engineers are continuing the process of calibrating Kepler's photometer in the dark, with its dust cover on. Because the instrument's charge-coupled device (CCD) focal plane (the area where light from the telescope will be focused) is so large, it does not have a built in shutter to keep light out. Kepler's focal plane is one square-foot, while the focal plane in your digital camera is the size of a fingernail. Dark calibration data are being taken at various sun angles, the first three of which are now complete. The forth attitude is designed to provide the darkest background and will point the telescope as far away from the sun as possible while maintaining enough sunlight on the solar panels to power Kepler's electrical systems. Once these data are analyzed and the calibration products are complete, a series of reviews will be convened to obtain approval to release the cover, which will separate from the spacecraft and follow its own orbit around the sun.
2009 March 17 14:00 UTC - Distance to Kepler:
1,244,000 km; 773,100 mi; 0.008 AU;
3.24 times the distance to the Moon.
2009 March 16 Mission Manager Update—Kepler is now more than 1 million kilometers (620,000 miles) from Earth, drifting away at the rate of about 1 kilometer per second. The past few days have been spent collecting data from the focal-plane array on Kepler's science instrument, the photometer, at various sun angles and temperatures as part of the calibration process. The focal-plane array, which contains 42 charge-coupled devices like those in your digital camera, is where light from the telescope is focused.
Each data set is sent down to Earth, or downlinked, over the Ka-band radio at a telemetry rate of 3.44 million bits per second to the 34-meter antennas of the Deep Space Network, located in the Mojave desert of California, outside Madrid, Spain, and near Canberra, Australia. As the Earth rotates, command of the spacecraft is periodically handed over from one of these stations to the next in a carefully choreographed process. During the period of commissioning ground controllers have round-the-clock communication with Kepler; once science operations begin communication will occur only twice a week.
2009 March 15 14:00 UTC - Distance to Kepler: 1,064,000 km; 661,000 mi; 0.007 AU; 2.77 times the distance to the Moon.
2009 March 14 14:00 UTC - Distance to Kepler: 970,300 km; 602,900 mi; 0.006 AU; 2.52 times the distance to the Moon.
2009 March 13 14:00 UTC - Distance to Kepler: 874,100 km; 543,200 mi; 0.006 AU; 2.27 times the distance to the Moon.
2009 March 12 Mission Manager's Update—Kepler's science instrument, called a photometer, was powered on by flight controllers and will be calibrated over the next several weeks. A dust cover remains closed over the front of the photometer so that Kepler's first images will be dark. The dark images help engineers characterize the noise in the instrument's electronics.
The spacecraft's powerful Ka-band radio transmitter was powered on and the vehicle was maneuvered to point its high-gain antenna toward Earth for testing. The primary set of reaction control thrusters was fired for the first time to zero out the small amount of angular momentum that, due to pressure from the sun's intense light, has built up in Kepler's reaction wheels. The reaction wheels are spinning masses used to control the orientation of the vehicle.
2009 March 11 Mission Manager's Update—After NASA's Kepler mission vaulted into the heavens on a column of thunder Friday March 6, it quickly sent its first communications to Earth via NASA's Deep Space Network station in the Mohave desert of California, called Goldstone. The spacecraft flew past the orbit of the moon Sunday night, and continues to trail behind Earth as it orbits the sun.
Flight controllers are busy proceeding through the methodical process of powering on and checking out Kepler's various systems. So far, the star cameras used to determine the orientation of the spacecraft, and the sun sensors used to determine the direction of the sun, have been checked out. In addition, the spacecraft's X-band radio communication link has been tested with the remaining two Deep Space Network stations, one near Madrid, Spain, and the other near Canberra, Australia. All systems are performing as expected and the commissioning process is proceeding smoothly.
2009 March 10 14:00 UTC - Distance to Kepler:
557,800 km; 346,600 mi; 0.004 AU;
1.45 times the distance to the Moon.
2009 March 9
14:00 UTC - Distance to Kepler
436,200 km; 271,100 mi; 0.003 AU;
1.13 times the distance to the Moon.
2009 March 8
4:00 UTC - Distance to Kepler
231,600 km; 143,900 mi; 0.002 AU;
0.6 times the distance to the Moon.
[Moon distance = 238,857 miles = 384,403 km.]
2009 Mar 7
March 7, 2009. RELEASE: 09-052 NASA'S KEPLER MISSION ROCKETS TO SPACE IN SEARCH OF OTHER EARTH
2009 Mar 6 Kepler Mission Rockets to Space in Search of Other Earths. Science@NASA.
2009 Feb 20 Kepler Mission to Hunt for Earth-like Planets. Science@NASA. Includes audio recording.