MXL students and Aerospace Engineering staff are spending this week at the Peach Mountain dish performing annual dish maintenance and prepping for upcoming proof of concept testing. The maintenance includes greasing all the bearings and gears. A software-defined radio and UHF antenna will then be installed in the feedhorn in order to test the ability to track and decode satellite transmissions. MXL’s RAX-2 satellite will be used initially as the signal source for testing.
Adding lubrication to the bearings for rotation in declination.
The Peach Mountain 26 m dish
Check out the official press release for RAX’s recent accomplishments. This was featured in such news sources as: Wall Street Journal Market Watch, R&D Magazine, Science Newsline, BetaNews, EurekAlert, Patexia, Solar Flares News, ITbriefing and others.
From the article: “The RAX radar echo discovery has convincingly proved that miniature satellites, beyond their role as teaching tools, can provide high caliber measurements for fundamental space weather research,” said Therese Moretto Jorgensen, Ph.D., Geospace program director in the Division of Atmospheric and Geospace Sciences at the National Science Foundation.
“The recently collected radar echoes allow us to determine the root cause and to possibly predict future disturbances in the auroral ionosphere – disturbances that can severely compromise communication and GPS satellites,” said Hasan Bahcivan, Ph.D., a research physicist in SRI’s Center for Geospace Studies, and principal investigator of the RAX mission.
A journal paper covering the design of the MXL-developed attitude determination subsystem that’s flown on RAX-1 and RAX-2 is now available online. See the RAX blog entry for more details.
Both RAX-2 and M-Cubed, CubeSats developed by MXL, are currently on-track to launch this Friday from Vandenberg Air Force Base in California! They are launching on a Delta II rocket with NASA’s NPP satellite as the primary payload. Be sure to check out the RAX and M-Cubed websites for more information. Current launch status can be found at Spaceflight Now’s launch status page.
We recently submitted a design paper on the attitude determination subsystem of the RAX-1 and RAX-2 satellites to the journal Acta Astronautica. This subsystem was custom developed by MXL, and it utilizes magnetometers, photodiodes, rate gyroscopes, and an extended Kalman filter to achieve better than 5 degree angular accuracy. The paper covers the complete design of the subsystem and will be helpful for other satellite development teams. The paper will now undergo a peer-review process before being published.
The abstract to the paper is as follows:
The Radio Aurora Explorer (RAX) is a triple CubeSat that launched on November 19, 2010. RAX was designed to study plasma irregularities in the polar lower ionosphere (80-300 km), and is the first satellite mission funded by the United States National Science Foundation. The scientific mission requires attitude knowledge within 5 degree (1-σ), and a custom attitude determination subsystem was developed for the mission. The subsystem utilizes rate gyros, magnetometers, coarse sun sensors, and an extended Kalman filter. In this paper, we describe the design, implementation, and testing of the RAX attitude determination subsystem, including derivation of the determination requirements, sensor selection, the integrated hardware design, pre-flight sensor calibration, and attitude estimation algorithms. The paper is meant to serve as a resource for others in the small satellite and nanosatellite communities, as well as a critical reference for those analyzing RAX data. Lessons learned from the design and performance of the RAX determination subsystem will be used in future designs of attitude determination systems for small satellites and similar platforms, such as high altitude balloons and autonomous aerial vehicles.