Mike Webb, right, and Rick Dykstra are seen at the radar and triplex consoles, tools used by Western Aeronautical Test Range staff to support space shuttles on orbit and during landings at Dryden and to maintain communication with the International Space Station. (NASA Photo by Tom Tschida) › View Larger Image
When a space shuttle was in orbit, or landed at Dryden, the Western Aeronautical Test Range staff was ready and waiting to assist.
Theirs was a capability the space shuttle crews appreciated. When the Atlantis crew was flying over Dryden on the July 16 final shuttle mission, they paid tribute to the center's historic contributions and its ongoing communications, tracking and telemetry support.
"Like to say 'hi' to the folks down in Dryden," said Atlantis Commander Chris Ferguson. "We really appreciated all the work they've done over the years. They've been with the shuttle program since the beginning, and they also give us critical comm[unications] right before we land there at Edwards.
Western Aeronautical Test Range, or WATR, employees include the radar, telemetry, communications, long-range optics and mission control room groups. Though they will no longer provide shuttle communications, WATR personnel have ongoing missions, such as support of flight research mission communications and telemetry and communications support for the International Space Station. (NASA Photo by Tom Tschida) › View Larger Image "They've been a super supporter over the years in orbit and in entry, and we can't thank them enough for all their contributions. We would not have been nearly as successful without them. So, just like to say 'hi' to all the folks down in Dryden today – the crew of STS-135 is thinking about 'em and we really appreciate all the work they've done," he said.
Ferguson is familiar with Edwards' capabilities, experiencing them firsthand when, as Endeavor commander, he landed the orbiter here on Dec. 30, 2008.
The WATR shuttle role, which is not much different from that of flight research range support, was coordination of center range assets and personnel with other NASA centers to support shuttle program stages, including launch, on-orbit requirements and landing. The WATR provided telemetry, radar, voice communication and video support for shuttle flights and will continue to provide services to the International Space Station.
On the orbiter's final mission, Dryden supported 69 orbits with radar. Included in that number were 45 orbits by Atlantis and 24 orbits by the International Space Station, said Arcata Associates' Robert Jones, WATR operations and maintenance manager. Dryden supported telemetry for 59 orbits, among them downlinks from the orbiter to Earth that included key transmission of a bulk of information known as information dumps.
"As the space station travels around the globe, there are about five or six opportunities a day for us to get a good track on it," Jones said. "The navigators in Houston [at Johnson Space Center] use our data along with data from other ground-based radars and from the TDRSS navigational system to do the mathematics to determine whether they've calculated the proper orbits, the proper position of the space station and proper calibration of the ground tracking systems and the TDRSS tracking system to make sure everything is ready."
The TDRSS refers to NASA's Tracking and Data Relay Satellite System.
The Western Aeronautical Test Range communications facility is the location for these quad yagi antenna arrays and other equipment used to provide communications to the International Space Station. (Photo courtesy Mike Yettaw) › View Larger Image The radar tracks are used to confirm the exact position of the shuttle in orbit, said Mike Yettaw, WATR communications and flight termination system group lead. The telemetry orbits are used to enable the shuttle to transfer data to the Dryden Aeronautical Test Facility, or ATF, site and then to Johnson Space Center.
The TDRSS station located at White Sands Missile Range in New Mexico provided the orbiter's primary voice communication link, and the WATR provided backup communication support for the TDRSS if a failure there occurred during a shuttle mission. The WATR facility was the primary means of communication support when an orbiter landed at Dryden.
The WATR also tracked the space station from the day prior to launch throughout shuttle missions, to provide critical docking and undocking information. During docking, Dryden capabilities were tapped to help engineers at Johnson Space Center calibrate calculations determining the orbiter's location in relation to the ISS. As the orbiter neared the space station, astronauts could manually control the shuttle through use of on-board computers, looking out windows to ensure safe docking.
WATR telemetry systems also provided downlinked orbiter health and status information to Johnson and, when needed, the telemetry systems also had the capability to provide uplinked command data to the orbiter.
Dryden began mission support two days before launch. After launch of an orbiter, the range tracked the shuttle until rendezvous with the space station. Two or three days before a shuttle returned, it undocked with the ISS. Dryden's two radars independently tracked the shuttle and the ISS for separation and rendezvous during 12-hour shifts that could start any time of the day or night, depending on the orbits.
In addition, on the day before a landing the Dryden crew ensured that radar, telemetry, communications and video were ready for landing. Shuttle crews tested S-Band uplink and downlink, the radar did an active track and Johnson engineers communicated with the shuttle using the Dryden communication facility's UHF voice equipment, Yettaw said.
Guy Thomas, Arcata Associates field services engineer, offered additional insight into WATR services.
"The Aeronautical Tracking Facility, or ATF, at Dryden was an integral part of shuttle operations for all 135 missions. Day and night, Dryden's high accuracy tracking radars provided precise positioning data needed to successfully guide the shuttle in orbit high above the Earth as well as during landing at Edwards," he said.
"The ATF's versatile telemetry antennas provided important communications links between Houston and the space shuttle while in orbit above the western United States, and when mission requirements led to a local landing, Dryden telemetry captured the pilot's point of view video and beamed the many flawless desert landings to television screens the world over.
"The shuttle program left an indelible mark on the Dryden ATF technicians and engineers who had the pleasure of tracking and communicating with the shuttle over its 30-year history."
Dryden has one of just two ground stations capable of sending and receiving communications on all of the available ISS frequencies, Thomas added. The other station is at Goddard Space Flight Center's Wallops Flight Facility. Goddard is located in Greenbelt, Md., and Wallops near Virginia's eastern shore. These emergency communication links were used in the past to resolve critical anomalies on the ISS and on the MIR before the ISS became operational. In both cases the emergency links were the only remaining operational links between Johnson Space Center and the ISS.
When a shuttle landed at Edwards and was prepared for transport, a 24-hour, seven-day-a-week umbilical connection to Kennedy Space Center via WATR facilities was activated to allow data gathered during the mission to transfer electronically.
Additional WATR support provided during landings at Dryden included long-range optical and infrared cameras, video vans for runway video coverage and the Mission Control Center that offered key support personnel a location in which to coordinate and monitor landing activities.
Whatever kind of space vehicles next travel to Earth orbit and beyond, Dryden will be ready to provide support with tracking, telemetry and communication needs when vehicles are overhead.