First Live Hd Broadcast from Space

December 4, 2006

FIRST LIVE HD BROADCAST FROM SPACE

On November 15, NASA transmitted the first ever live high definition pictures from space. The broadcast, from the International Space Station (ISS), was carried out in cooperation with the Japan Aerospace Exploration Agency, Discovery Channel, and Japanese broadcast network NHK.

The twenty-minute HDTV broadcast was carried live by Discovery HD Theater and by NHK in Japan, and displayed in other venues. The program featured Expedition 14 Commander Michael Lopez-Alegria, describing life aboard the International Space Station orbiting 220 miles above the earth’s surface. Flight Engineer Thomas Reiter served as camera operator.

The project was conceived by NASA Digital TV Program Manager and Principle Investigator Rodney Grubbs, who said, "HDTV provides up to six times the International Space Station resolution of regular analog video. On previous (Image from NASA) missions, we've flown HDTV cameras but had to wait until after the mission to retrieve the tapes, watch the video, and share it with the science and engineering community, the media and the public. For the first time ever, this test lets us stream live HDTV from space so the public can experience what it’s like to be there. The system transmits high bandwidth digital television signals to the ground that are not only spectacular, but also valuable to scientists, engineers, and managers.”

The camera used on board the ISS was a standard Sony HDW-750 HDCAM feeding a 1080i signal through a SMPTE HD-SDI 292M interface to a newly developed Space Video Gateway (SVG) system installed on the ISS. The microphone audio signal was also fed to the SVG. After MPEG-2 compression, the video and synchronous audio signal was packetized for transmission in a 30 Mbps Internet Protocol (IP) stream.

The system diagram, provided to NAB by Mr. Grubbs, shows the main system components and transmission path. The output of the SVG went over a fiber optic link to the main data communication system on Display in Times Square, the ISS, which uses a NASA proprietary system for radio New York communications with the ground. The previous maximum data rate (Image from Discovery Channel) used by NASA had been 6 Mbps, so successful synchronous transmission at 30 Mbps was a breakthrough in capacity.

A geostationary TDRSS satellite is used as a relay point for the wide-band communications link from the ISS. For the 20-minute broadcast, the orientation of the ISS had to be adjusted slightly to maintain the pointing accuracy for the high gain microwave antenna pointing at the geostationary satellite.

Signals from the satellite are downlinked to the ground station at the NASA White Sands Test Facility (WSTF) in New Mexico. From there, it is fed via fiber optic link to the Johnson Space Center (JSC) in Houston, Texas. For the HDTV project, a Ground Video Gateway (GV) at JSC brought the video and

International Space Station HDTV System Diagram (Courtesy of NASA) audio back to baseband, with DVB-ASI, HD-SDI, and AES3 audio outputs. These signals were made available to Discovery and NHK for onwards transmission. Discovery Communications’ Director of Affiliate Technology and Standards, Charlie Myers, was responsible for technical coordination and he arranged to re-encode the signals at about 40 Mbps using a Tandberg MPEG-2 encoder at JSC, with relay of the signal to the Discovery facility in Sterling, Virginia over C band and Ku band satellite links.

The Space and Ground Video Gateways were developed by NASA and are based on a Crystal Group CS900 server, with industry plug-in PC cards. Video compression is provided by an HDTVxpressTM Compressor PCI board from LSI Logic Corporation and IP packetization and depacketization carried out with a DVB Master FD PCI board from DVEO. The computer platform and cards all had to go through stringent NASA tests to verify reliability in the demanding space environment.

The HDCAM camera, provided by NHK, was delivered to the ISS on the Space Shuttle Atlantis in September. It has been found that CCD imaging devices are susceptible to damage when in the space environment without the protection of the earth’s atmosphere, believed to be due to high- energy solar radiation. Although the camera had only been in space for a few weeks, it had evidently suffered such damage and a number of dead pixels were visible as fixed defects in the HD pictures. While this did not detract from the usefulness of the broadcast, it would seem to be an area that camera and CCD manufacturers will need to address for long-term use of such cameras in space.

There are no immediate plans to repeat the live HD video linkup. But now the technology has been proven, there will certainly be opportunities in the future to show important events in HDTV. Perhaps for a landing on Mars – the difference from the fuzzy pictures of the moon landings in the 1960s would certainly be spectacular!

For more information about the International Space Station and the Expedition 14 crew, visit: http://www.nasa.gov/station