Headlines

A closeup image of Mercury's surface captured by MESSENGER's camera on October 6, 2008. (NASA/Johns Hopkins Univ. Applied Physics Laboratory/ Carnegie Institution of Washington)

Photos from Mercury

MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging), the first spacecraft sent to orbit Mercury since 1975, completed its second flyby on October 6, 2008. By the next day, images of the planet closest to the sun were being received on Earth.

The images showed that cooling of the planet's iron core has caused shrinking and cracking on the surface, creating a jagged landscape with sheer cliffs and mountains. Silicon, sodium, and sulfur were detected, as well as water—most likely in the form of ice in the planet's many crevices and craters.

This mission, initially launched in August 2004, has already started answering scientists' questions regarding the small planet. For example, the presence of volcanoes was confirmed with the discovery of an apparently dormant volcano 60 miles in diameter with a 14-mile crater.

MESSENGER's voyage will include one more flyby of Mercury before entering into a year-long orbit of the planet in March 2011.

Probing the Interstellar Boundary

The Interstellar Boundary Explorer (IBEX) spacecraft was successfully launched from Kwajalein Atoll aboard a Pegasus rocket into a high Earth orbit on October 19, 2008. It will observe for the first time the global interactions between the solar wind and interstellar medium.

IBEX will explore the region of violent turbulence beyond the boundaries of the solar system, a region of compression known as the termination shock. Voyager 1 hit the region in 2004, and Voyager 2 collided with it in 2006. The two spacecraft came in contact with the region at different times, suggesting that the termination shock is irregularly shaped.

IBEX will help determine whether this is the case and where the termination shock begins. The spacecraft will carry two energetic neutral atom cameras to capture images of the low-density matter between stars. "The key is that the cameras carried by IBEX measure energetic neutral atoms of hydrogen, in effect imaging the shape and structure of the heliosphere termination shock," said Matthew Hart, systems director, Flight Projects Engineering, NASA Advanced Programs Division.

One of the benefits of this mission is that the results will be readily available, and measurements can be taken from Earth orbit as opposed to waiting for a probe to reach deep space.

Hubble Up and Running

The Hubble Space Telescope servicing mission scheduled for October 14, 2008, was postponed by NASA after a crucial component of the Science Instrument Command and Data Handling unit onboard the spacecraft failed, disabling the orbiting observatory so that it could not command its scientific instruments and return science data to the ground. The component, called the Control Unit/Science Data Formatter, is one of 14 components of the instrument.

To recover operation of the telescope, NASA engineers switched from the failed computer to its redundant backup that had been "asleep" on board the spacecraft for 18 years. Engineers were not sure if the unit would respond, but they were successful in bringing it online, and Hubble began sending back images on October 27, 2008. NASA now wants to replace the command and data handling unit during the next space shuttle servicing mission, thus delaying the flight until at least May 2009. NASA has a replacement system available, but it has been in storage since 1991, so it must undergo a rigorous set of tests to prove it is flightworthy.

Since the spacecraft is now operating on the backup data formatter, it can tolerate no subsequent failures of that component and continue to send back images. "Now that the computer is back online, Hubble is expected to provide uninterrupted science data collection through the servicing mission delay period," said Allan Cohen, senior project leader for Aerospace support to the Hubble program office at NASA's Goddard Space Flight Center. The new servicing launch date also postpones replacement of critical gyros, although the spacecraft should be able to operate normally while waiting for its tune up. "NASA's current approach to managing gyro operation is based on results of Aerospace reliability analyses and allows extension of science operations beyond that of earlier approaches," said Cohen.

More information about Aerospace support to Hubble can be found in NASA's Greatest Observatory—The Hubble Space Telescope in this issue.

A few days after the orbiting observatory was brought back online, Hubble aimed its prime-working camera, the Wide Field Planetary Camera 2, at a pair of gravitationally interacting galaxies called Arp 147. The image showed that the camera is working as it was before going offline in September. (NASA)

"First Light" for Airborne Laser

The Missile Defense Agency's Airborne Laser (ABL) program has achieved a significant milestone. The agency's high-energy Chemical Oxygen Iodine Laser (COIL) was successfully fired in a ground test at Edwards Air Force base in California on September 7, 2008. The test, known as the "first light," validated the integration, operation, and control of the six laser modules that form the main flight laser and their related optics. The COIL was installed in early 2008 on a modified 747 aircraft. The back holds the laser, while the front contains the beam-control and battle-management systems. In this ground test, the laser was fired into a calorimeter installed onboard the aircraft to capture and characterize the beam. In future ground tests, the beam will be sent through the beam-control/fire-control system and out of the forward turret.

Aerospace serves on the five-member government/industry team charged with overall program technical guidance, said James Thordahl, systems director of the Directed Energy Department of the Missile Defense Division. "As part of the first light milestone, Aerospace reviewed test results, determined whether test objectives were met, and participated in the recommendation to declare this milestone complete," he said.

This was the first time the integrated laser system was operated in the ABL aircraft, said Thordahl. Previous ground testing was accomplished in a surplus 747 fuselage known as the Systems Integration Laboratory. Testing of the ABL is expected to culminate in 2009 with an airborne intercept test against a ballistic missile. For more details, see the Winter 2008/2009 issue of Crosslink.

NFIRE Mission 2B Successful

US Air Force

The Near Field Infrared Experiment (NFIRE) satellite successfully tracked a test target launched from Vandenberg Air Force Base on September 23, 2008. The test, designated NFIRE Mission 2B, was the second for the low Earth orbiting satellite, which was launched on April 24, 2007. The first test, NFIRE Mission 2A, took place on August 23, 2007. The target launch was an opportunity for NFIRE to collect high- and low-resolution images of a boosting rocket to improve understanding of missile exhaust plume observations and plume-to-rocket body discrimination. Data from NFIRE were downlinked to the Missile Defense Space Experimentation Center, part of the Missile Defense Integration and Operations Center at Schriever Air Force Base in Colorado. Experience gained through NFIRE will support the design and development of future Missile Defense Agency (MDA) space projects.

"Aerospace played a critical mission-assurance role for this test," said Keith Zondervan, associate general manager for Missile Defense Space Systems. Personnel from the Missile Defense Space Systems organization and the Missile Defense Division performed an independent mission-readiness assessment for MDA, working round the clock to complete the assessment on time. "Our MDA customers were extremely pleased with the Aerospace contributions to achieving this outstanding success," said Zondervan.

Sending Out an SOS

The students of the 2007–2008 Harvey Mudd College Engineering Clinic Team have developed an optical distress beacon to aid astronauts working outside their spacecraft. The device could provide an alert in an emergency if an astronaut became incapacitated or were unable to contact the space vehicle.

The students developed two designs. The first integrates with an existing picosatellite architecture. The second involves a distributed system composed of a single control unit and multiple optical emitters placed around an astronaut' s spacesuit and activated wirelessly. The control unit would connect to health sensors in the spacesuit. An emergency would trigger the optical emitters, which are light-emitting diodes visible up to 800 meters away.

The project was conducted through Aerospace's Corporate University Affiliates Program (CUAP). Samuel Osofsky, associate director of the Communication Electronics Department and liaison for Harvey Mudd College through CUAP, said, "The main idea was that when an astronaut on a spacewalk suffered an incapacitating injury, the 'sensors' on the astronaut would be the eyes of those in the space vehicle." The students applied for a patent and presented a paper at the third International Association for the Advancement of Space Safety Conference held in October, 2008, in Rome, Italy.

CUAP was initiated in 1997 to create formal relationships between Aerospace and select universities. Participating universities and academic departments engage in formal agreements with Aerospace to accomplish specific tasks and share technical information.

To Winter 2008/2009 Table of Contents