Headlines

Next Fleet of GPS

(The Boeing Company)

The Air Force has awarded a $138 million contract to begin work on developing three additional satellites for the next series of the Global Positioning System (GPS) fleet, the Block IIF. These satellites will be the newest addition to the GPS family, and are scheduled to be delivered in 2008.

The IIF satellites will be enhanced with a new L5 navigation signal, which is located at 1176.45 megahertz in the aeronautical radio navigation services spectrum. When used jointly with the current L1 coarse acquisition signal, the L5 signal will allow users to remove ionospheric errors, improving accuracy by a factor of 2. It is also designed to incorporate more robust code-division multiple access sequences, more power, and a message-based format for its navigation data. "The IIF satellites will have improved mission performance and enhanced capability, including new military and civilian codes," said John E. Clark, principal director, Space Systems Navigation Division.

Aerospace's involvement will include verifying requirements compliance; reviewing parts, materials, and processes; assessing design readiness and test results; augmenting contractor analysis of failures; overseeing integration with the Evolved Expendable Launch Vehicle; and participating in the launch and operation of the satellites.

Microsatellite Launch

(The Boeing Company)

A Delta II rocket successfully launched the Micro-Satellite Technology Experiment (MiTEx) from Cape Canaveral on June 21, 2006. MiTEx is made up of two 500-pound microsatellites and an upper stage developed by the Naval Research Laboratory. The satellites are designed to test technologies for future military programs. The project is a collaboration between the Defense Advanced Research Projects Agency, the Air Force, and the Navy.

MiTEx will investigate and demonstrate advanced space technologies such as lightweight power and propulsion systems, commercial off-the-shelf processors, affordable and responsive fabrication and build-to-launch techniques, and new components.

Aerospace involvement in the project included technical support for the hardware review, assistance with the power and control box assembly, and acceptance testing. Aerospace launch support included technical assistance in the avionics and electrical areas, spin balance mass determination, spacecraft fueling support, payload processing, test data on flight assemblies and subassemblies, slosh parameter calculations and roll plane analysis, trajectory and performance simulation and verification, and assistance to the independent readiness review team.

Delta IV Launches from SLC-6

(The Boeing Company)

The first California launch of a Delta IV rocket took place at SLC-6 at Vandenberg Air Force Base on June 27, 2006. The Delta IV, an Evolved Expendable Launch Vehicle (EELV), carried a classified National Reconnaissance Office (NRO) satellite into orbit. It was the tallest rocket ever launched from Vandenberg, and the first EELV to carry an NRO payload. The event marked the sixth successful Delta IV launch.

After a beautiful morning, strong winds came in and threatened the launch. But later, calmer winds prevailed, the go-ahead was granted, and final preparations were made for the vehicle's liftoff. SLC-6 has quite a history, and the ominous weather may have reminded some people of past attempts to use the site. The launchpad was first constructed in the 1960s for the Air Force's Titan III in support of the Manned Orbiting Laboratory program, which was canceled before the first flight.

Later, the site was reconfigured to launch space shuttles, but that plan, too, was scuttled after the 1986 Challenger disaster. The Air Force leased SLC-6 to a contractor during the 1990s, but the site was unused by the military, and actually sat in mothball status for close to 30 years. "I am extremely proud of the entire team. This was a historic launch for both the Delta IV and SLC-6, " said Ray Johnson, vice president, Space Launch Operations. Another Delta IV is planned for launch from Vandenberg in late 2006.

Space Shuttle Mission Support

The space shuttle Discovery safely returned from a 13-day mission to the International Space Station on July 17, 2006. It was the second shuttle flight since the loss of Columbia in 2003. Aerospace has been working with NASA since 2003 on numerous studies involving mission safety, including research on external tank foam debris, micrometeoroid and orbital debris, and tin-whisker growth in critical avionics boxes.

(NASA)

As part of these efforts, Aerospace has been helping NASA implement an integrated damage/risk validation process with models designed to assess the overall external tank foam hazard and prioritize long-term mitigation efforts. This has been done through technical inputs, analysis, experimental testing, and imagery reviews. The team has used in-flight imagery to account for historical foam loss and to correlate observed losses with actual orbiter damage data. The risk models are designed to account for damage from all observed foam debris and can perform assessments through simulation. The program also calls for each space shuttle crew to collect in-flight imagery. The team can then assess the integrity of the orbiter's thermal protection system to distinguish damage incurred to the vehicle during ascent from on-orbit damage from micrometeoroids or other orbital debris.

Aerospace has developed a wind tunnel test program to evaluate ice that falls from the shuttle during initial ascent and its breakup characteristics. NASA has asked Aerospace to develop a similar combined-environments wind tunnel test program to characterize crushed-foam failure and other foam failure modes. The risks of micrometeoroid and orbital debris, uncertainties and limitations in data collection, and lessons learned were shared by Aerospace at the STS-121 Safety and Mission Success Review, and the findings directly influenced NASA's decision to conduct a late on-orbit inspection of the shuttle before its July flight.

(NASA)

Aerospace also assisted in ground testing on Discovery after its return from the STS-114 mission in August 2005. The work was conducted to investigate the failure of an avionics unit in the orbiter's flight control system. The research revealed a profusion of metal filaments growing from tin-plated card guides. This phenomenon is well known in the avionics and computer industries as tin whiskers. A tin-whisker infestation can compromise the performance of electronic units and can be dangerous if the electronics are critical to mission safety. Aerospace had already been studying tin-whisker growth for the Air Force and Department of Defense, and has now begun to work with NASA to address tin-whisker growth in critical flight control components on the space shuttle. A short circuit in the reaction-jet driver could put both the shuttle orbiter and the International Space Station at risk if the jets fail during rendezvous. NASA plans to replace the flight control system boxes over the next several shuttle flights to mitigate tin-whisker growth and has recommended developing a comprehensive plan for addressing tin-whisker risk for all NASA programs.

To Fall 2006 Table of Contents