Kepler Spacecraft Relays Star Data to Earth

NASA's Kepler spacecraft is currently located 32 million kilometers from Earth. Its mission is to discover Earth-size planets in or new the habitable zone and determine how many of the billions of stars in our galaxy have such planets. The Kepler spacecraft uses two different systems to communicate with Earth.

While it is in its "science attitude," it uses a lower data rate (10 bps to 16 Kbps) X-band system with a low-gain antenna. A Ka-band system with a data rate of up to 4.33125 Mbps using a high-gain antenna is available, but it is not pointed at the Earth while the satellite is collecting in its science attitude.

On Tuesday, April 26, NASA reoriented the Kepler spacecraft to allow use of the high-gain antenna and successfully download all data collected since March 20. The download required 45 minutes for engineering data, and 5.25 hours for 37 days of science data. In all, 93 gigabits of data were downloaded before the spacecraft was reoriented to science attitude. The project team must now wait for the spacecraft to return to the thermal condition it was in before the break. When the sun shines on a different part of the structure, it warps slightly, changing the angle between the star trackers and the telescope line of sight. The total break, including collection of calibration data, was about 17 hours, less than the 20 hours allowed per month.

The data is downlinked using NASA's Deep Space Network and sent to the Mission Operations Center in Boulder, Colo. and on to the Data Management Center in Baltimore where the raw pixel data is archived. The data is then transmitted to the Kepler Science Operations Center at NASA's Ames Research Center at Moffett Field, Calif.

Doug Lung

Doug Lung is one of America's foremost authorities on broadcast RF technology. As vice president of Broadcast Technology for NBCUniversal Local, H. Douglas Lung leads NBC and Telemundo-owned stations’ RF and transmission affairs, including microwave, radars, satellite uplinks, and FCC technical filings. Beginning his career in 1976 at KSCI in Los Angeles, Lung has nearly 50 years of experience in broadcast television engineering. Beginning in 1985, he led the engineering department for what was to become the Telemundo network and station group, assisting in the design, construction and installation of the company’s broadcast and cable facilities. Other projects include work on the launch of Hawaii’s first UHF TV station, the rollout and testing of the ATSC mobile-handheld standard, and software development related to the incentive auction TV spectrum repack.
A longtime columnist for TV Technology, Doug is also a regular contributor to IEEE Broadcast Technology. He is the recipient of the 2023 NAB Television Engineering Award. He also received a Tech Leadership Award from TV Tech publisher Future plc in 2021 and is a member of the IEEE Broadcast Technology Society and the Society of Broadcast Engineers.