NASA will use IP to talk it up
NASA will use IP to talk it up
Voice system will let far-flung scientists confer about experiments in space
By William Jackson
NASA is building a voice over IP system to help earthbound scientists stay in touch with their experiments on the International Space Station.
NASA's Internet Voice Distribution System will keep scientists worldwide in touch with their experiments in space, some of which will run for months or years.
Up to 200 scientists around the world will talk with payload specialists at the Marshall Space Flight Center in Huntsville, Ala., over the Internet Voice Distribution System, said Bob Bradford, an engineer with the Payload Operations Center. The center will manage the experiments.
Bradford said 99.9 percent of the traffic will be terrestrial, but links to the orbiting space station also will be available.
AZ Technology Inc. of Huntsville is developing the system with collaboration software from White Pine Software Inc. of Nashua, N.H.
A voice over IP system now linking Marshall with schools around the country has been the test bed. The primary difference is that the space station system will allow conferencing, whereas the educational system is point-to-point.
The International Space Station, a cooperative effort of NASA with the European Space Agency, Canada, Japan and Russia, is scheduled for completion in 2003.
While NASA was operating the Skylab space station, scientists came to the agency's facilities for anywhere from six months to a year while their orbital experiments went on. Bradford called that requirement 'very disruptive.'
It would have been too expensive to install dedicated circuits to extend the Marshall voice switch to communicate with the scientists'up to $30,000 per site.Internet alternative
'The alternative was voice over the Internet to allow scientists to conduct an experiment from home,' Bradford said.
NASA tapped AZ Technology about three years ago to see whether such a system was practical.
'We configured computers in 26 schools and held a series of 'Ask the Astronaut' sessions,' said Jim Chamberlain, project manager for AZ Technology. 'It's been a good way to test out the concept.'
The school system uses voice server and client software from VocalTec Communications Ltd. of Fort Lee, N.J.
'We found that the system worked, and quality was excellent,' Bradford said. 'We had a few network congestion problems but nothing we couldn't live with.'
Most scientists using the voice system probably will have access to IP networks far faster than the Internet, such as the National Science Foundation's very-high-speed Backbone Network System, Bradford said.
The school computers ran telemetry processing software to test how well the experimental data traveled over the Internet via the User Datagram Protocol, which can replace the Transmission Control Protocol when reliable delivery is not required.
UDP does not acknowledge or guarantee delivery.
'There definitely was a lot of packet loss and rearrangement' in the UDP transmissions, Chamberlain said. 'This will require some enhancements at the client end to compensate.'
VocalTec does not sell conferencing products, so AZ Technology chose White Pine's MeetingPoint server and CU-SeeMe client for the space station system.
CU-SeeMe Web supports voice, video and data collaboration, but Marshall will use only the voice capability. With a development kit provided by White Pine, AZ Technology will spend the next year developing a custom interface for payload specialists at Marshall to monitor multiple conferences on PCs, muting and joining them as needed.
The space station conferences, or loops, will be a set of always-on connections among sets of users. 'People will use specific loops for different needs,' Bradford said.
Built-in security will define each user's loop access. Scientists who have the specially configured client software can stay in touch with the Payload Operations Center 24 hours a day while their experiments are running.
AZ Technology also will modify a White Pine administrative management server to let Marshall administrators manage and allocate bandwidth and connect with NASA databases.
The MeetingPoint server runs under Microsoft Windows NT, SunSoft Solaris or Linux. Bradford said he expects to use NT and is considering a Compaq ProLiant server for it, although he has not made a decision.
By February, two MeetingPoint servers will be at Marshall.
As the system scales up, additional servers could be installed at other NASA centers as well as at foreign locations, said Gary McGuire, director of government sales for White Pine.