Screenshot from ULA Webcast of the TDRS-L launch. Another late night launch just waiting for GO
Mission Rundown: ULA - Atlas V 401 - TDRS-L
Written: February 2, 2023
Covering all bases in space
United Launch Alliance successfully conducted their first mission of 2014 by launching an Atlas V 401 rocket on Thursday evening January 23, thus deploying NASA’s latest Tracking and Data Relay Satellite, TDRS-L.
Liftoff from Cape Canaveral Air Force Base Space Launch Complex 41 occurred at 21:33 EST local time - equivalent to 02:33 UTC on Friday.
Flight path of TDRS-L from SLC-41. With one long burn Centaur is in geostationary transfer orbit
The TDRS-L payload
The twelfth spacecraft in NASA’s Tracking and Data Relay Satellite System (TDRSS), TDRS-L is the second of the three third-generation satellites.
TDRS-L is a 3,454 kilogram (7,615 lb) satellite which was manufactured by Boeing and is based around the BSS-601 satellite bus.
TDRS-L has a design life of 15 years, however most TDRS satellites have significantly exceeded their design expectations. The satellite carries an R-4D-11-300 apogee motor to raise itself into its final orbit and carry out other maneuvers.
TDRS-L is powered by solar panels, generating between 2.8 and 3.2 kilowatts of power depending on illumination.
The satellite carries s-band phased array antenna to allow simultaneous communications with five other spacecraft, as well as two steerable antennas providing S, Ku or Ka band coverage to spacecraft requiring communications at a higher data rate.
TDRS satellites are used by NASA to provide communications links between spacecraft in orbit – including the International Space Station and Hubble Space Telescope – and ground controllers. Part of NASA’s Space Network, TDRSS was implemented to reduce NASA’s dependence on ground stations and airborne tracking assets.
Use of the network is not restricted to NASA missions; amongst other users United Launch Alliance and Sea Launch both use TDRS to relay data from their rockets during launch, JAXA and the European Space Agency have used TDRS for missions, including HTV and ATV flights to the ISS, and the system is rumored to be used by NRO - the National Reconnaissance Office to supplement its own Satellite Data System, transmitting data from reconnaissance satellites for analysis.
Older satellites in more highly-inclined orbits have been used to relay communications to the Amundsen–Scott Station at the South Pole; a site not usually accessible to communications satellites due to its extreme latitude.
The Atlas V 401 launch
The launch of AV-043, which marked the forty-third flight of an Atlas V, began with the ignition of the RD-180 engine at T-2.7 seconds. Its thrust exceeded the mass of the rocket about 1.1 seconds after T-0, allowing the vehicle to rise off the pad and begin its ascent.
Climbing vertically for 16.4 seconds, AV-043 cleared the pad before it began a series of roll, pitch and yaw maneuvers to place it onto the planned trajectory to achieve geosynchronous transfer orbit.
The rocket flew downrange on a heading of 101.4 degrees, passing through the area of maximum dynamic pressure, or Max-Q, 91.3 seconds after liftoff.
Booster Engine Cutoff, or BECO, marked the end of first stage flight, occurring four minutes and 1.9 seconds into the mission, with the Common Core Booster separating six seconds later.
After staging, the Centaur’s RL10 engine began its pre-start sequence; with ignition occurring ten seconds after the spent stage had been jettisoned. Ignition of the Centaur, or Main Engine Start 1 (MES-1), began the first of two planned burns for the upper stage during Thursday’s mission.
The first Centaur burn lasted 13 minutes and 55.1 seconds, with separation of the payload fairing from the nose of the rocket occurring eight seconds after ignition. At the end of the burn, a lengthy coast phase began.
The coast phase lasted an hour, twenty one minutes and 54.7 seconds, before the RL10 ignited again for its second burn. This raised the perigee of the orbit, reducing the amount of fuel TDRS-L must expend to reach its final destination.
By using less fuel at this phase of the mission, TDRS-L will have more available for maneuvering and stationkeeping, potentially allowing it a longer operational mission.
The second burn lasted 63.1 seconds. Four minutes and 46 seconds after it ended, TDRS-L was separated from the Centaur to begin its own mission. The target orbit for spacecraft separation is a 4,839 by 35,788 kilometers (3007 by 22,238 mi; 2613 by 19,324 nmi) inclined at 25.5 degrees to the equator, with an argument of perigee of 180 degrees.
The Atlas V 401 rocket
The rocket which deployed TDRS-L was an Atlas V 401, tail number AV-043. The smallest Atlas V configuration, the 401 variant consists of a single Common Core Booster (CCB) first stage, and a Single-Engine Centaur (SEC) upper stage.
The Common Core Booster is powered by a single RD-180 engine, derived from the RD-170 developed by the Soviet Union to power its Zenit rocket and the Centaur is powered by an RL10A-4-2 engine. The 4.2 meters (13 feet) payload fairing will encapsulate TDRS-L.
The Atlas V 401 rocket, tail no. AV-043 is standing 57.31 meters - 188 feet tall on SLC-41.
Atlas V 401 split in its major parts. This is a generic non mission specific graphic configuration
Facts on the Atlas V 401 launch vehicle
Height of Atlas V 401: 188 feet (57.31 meters)
Mass at liftoff: 336,582 kilograms - 740,480 pounds
Thrust at liftoff: 3.8 mega-Newtons - 0.86 million lbf
Fuel onboard: 91,000 gallons of liquid propellant
LOX+LH2 = 66,000 gallon of cryogenic liquid propellant in three tanks
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