Atlas 2A Launches TDRS-J to Orbit

An Atlas 2A successfully launched TDRS-J (10) from Cape Canaveral’s pad 36A at 02:42 UTC on December 5. The spacecraft was placed into a geosynchronous transfer orbit. The satellite will be positioned at 150°W where it will deploy its antennas and undergo on-orbit testing and checkout. After being checked-out it will be accepted by NASA and renamed TDRS-10. The Tracking and Data Relay System (TDRS) satellite will be owned and operated by NASA.

The 3192 kg (7031 lbm) satellite was built by Boeing Satellite Systems, using a BSS 601 satellite bus. The satellite carries S-, Ku- and Ka-band transponders. Each TDRS satellite can receive data rates at 300 megabits/second (Mbps) using Ku- and Ka-band, and 6 Mbps at S band. Each spacecraft carries the additional capability for Ka-band receive rates of up to 800 Mbps. Transmit data rates are 25 Mbps for Ku- and Ka-band, and 300 kilobits/second (Kbps) for S-band. In addition, the S-band phased array antenna can receive signals from five spacecraft at once, while transmitting to one. The TDRS satellites are unique in their ability to follow the motion of fast moving spacecraft, providing nearly continuous communication with controllers and researchers on Earth. In addition to the International Space Station (ISS) and Space Shuttle, other programs using the TDRS constellation include the Hubble Space Telescope, STARlink, the Tropical Rainfall Measuring Mission (TRMM), Landsat, and Earth Observing System (EOS). TDRS also provides expendable launch vehicle tracking services to launch service providers. It is possible a future TDRS block could be developed in cooperation with the Department of Defense, or NASA might procure its telecommunication services from commercial operators. Currently there are nine TDRS spacecraft in Earth orbit, which includes six older TRW-built satellites.

NASA's Goddard Space Flight Center selected Boeing Satellite Systems on February 23, 1995, to build the next-generation H,I,J Tracking and Data Relay Satellites (TDRS) awarding a US$481.6 million contract. The TDRS H,I,J procurement was the first in which NASA followed a number of commercial practices, such as identifying requirements and letting contractors develop solutions to meet them, versus developing detailed specifications and requiring contractors to follow them. To enhance its financial efficiency and hardware reliability, NASA changed to greater contractor accountability with the contract specifying a payback schedule to reimburse NASA for any failures incurred during the first 8 years of the satellites' 11-year operational lifetime.

Boeing had problems, which were eventually resolved, during the delivery of the first two TDRS satellites of this block purchase.

NASA's acceptance of TDRS-H, now TDRS-8, was delayed due to a performance shortfall on the Multiple-Access (MA) phased array antenna aboard the spacecraft.  During on-orbit testing in August 2000, Boeing Satellite Systems, Inc., discovered that the MA communication services were performing at less-than-specified capability. All other communication services were activated and tested and performing well. NASA and Boeing reached an accommodation over the design flaw, which has been corrected in the later two spacecraft.

TDRS-I, launched earlier this year on March 8, developed a problem with its onboard supply of propellant when one of the spacecraft's two propellant fuel tanks did not properly pressurize. The Atlas 2A has placed the satellite in an elliptical geosynchronous transfer orbit (GTO), with the satellite on-board propulsion system expected to take two weeks to complete the raising of the spacecraft to its geostationary mission orbit. Satellite controllers at Boeing Satellite Systems, El Segundo, CA, successfully rerouted fuel tank pressurant around a blocked valve and conducted a series of engine burns over four months to raise TDRS-I to geostationary orbit completing the last burn on September 30. Upon reaching its operational orbit the spacecraft deployed its antennas and began at least eight weeks of on-orbit testing. Based on the remaining amount of propellant, the satellite is expected to fulfill its contractually required service life. Once the checkout is completed, NASA will take complete ownership of the spacecraft from Boeing, and rename it TDRS-9.

Prior to deployment of TDRS NASA depended on many ground-based tracking and data acquisition systems to receive data from spacecraft and keep track of their location. The ground stations were located all over the globe in order to maintain continuous contact with all of the satellites. To replace the costly overseas ground stations NASA developed the Tracking and Data Relay System (TDRS) to relay data from a geosynchronus satellite to a single ground station at White Sands, NM. The first TDRS satellite was launched in April 1983 by the Challenger space shuttle. The first seven TDRS spacecraft were built by TRW and launched on shuttles, one of which was lost in the 1986 Challenger disaster.

This flight, AC-144, marks the 23rd and final Atlas 2A launch. Atlas began as the first U.S. intercontinental ballistic missile (ICBM) during the 1950s. At the same time Atlas was being developed as an ICBM, the USAF began supplying the vehicles to NASA for space applications. The commercial launch services program for Atlas was initiated in June 1987, with the first commercial launch in July 1990. The first Atlas 2 version flew in December 1991, followed by the Atlas 2A in June 1992, and the Atlas 2AS in December 1993. The Atlas 2AS, a version of the Atlas 2A with four strap-on boosters, has five more flights remaining before it is retired, and the Atlas 3 has 7 flights remaining. The Atlas family of rockets is produced by Lockheed Martin Space Systems Co., Denver and marketed by International Launch Services (ILS), McLean, VA. This was the 11th satellite launched for NASA under the ILS commercial Atlas program. ILS is a joint venture of Lockheed Martin Corp., Khrunichev State Research and Production Space Center and RSC Energia. ILS markets and manages the missions for the Atlas and the Russian Proton launch vehicles.

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