WALLOPS ISLAND, Va — Orbital Sciences Corp. has successfully launched its Antares rocket on the long-delayed “A-ONE” test flight from Pad 0A at the Mid-Atlantic Regional Spaceport (MARS) on Wallops Island, Va. Liftoff of the 133-foot-tall vehicle – the first cryogenically-propelled rocket ever built and flown by Orbital – occurred on time at 5:00:02 p.m. EDT, right at the start of the launch window. Antares’ beautiful ascent into the early evening sky has surely raised an unbearable weight from the shoulders of Orbital, whose next focus after this mission is to conduct a full-up demo of its Cygnus cargo ship to the International Space Station, possibly as soon as June.
The launch proved charmed with third-time-lucky fortune, as Orbital saw its baby finally fly. Two previous attempts were scrubbed due to technical and weather issues. On Wednesday, a data umbilical cable linking the Transporter Erector Launcher (TEL) to the rocket’s second stage prematurely disconnected and prompted a scrub, just 12 minutes ahead of the scheduled liftoff. A second attempt yesterday was also frustrated, not by a technical issue, but by unacceptable high-altitude winds. However, evaluations late last week placed the Orbital team in a position to attempt two back-to-back launch attempts on Saturday and also today, during a two-hour window which extended from 5:00-7:00 p.m.
Weather conditions at Wallops at dawn this morning seemed to show a marked improvement over yesterday and the A-ONE flight controllers received their “Call to Stations” at around 9:00 a.m. AmericaSpace’s Launch Tracker noted meteorologists’ predictions of an 80-percent probability of acceptable conditions at T-zero, with the main worry focused on a chance that surface winds could violate the launch attempt. However, balloon deployments during the early afternoon returned positive results, indicating that weather conditions and the range debris limits were both “Green”.By 2:00 p.m., the process of chilling-down the fuel lines of Antares’ first stage – which is powered by two Aerojet-built AJ-26 engines – with liquid nitrogen had begun, ahead of the fueling process. This hour-long ‘chill-down’ protocol, explained the Tracker, was designed to “prevent a shock to the equipment being hit by a rapid temperature change which could cause a catastrophic failure”. Finally, a little after 3:30 p.m., the A-ONE launch team was polled for its recommendation and returned a unanimous “Go” to march towards a liftoff at the opening of the window at 5:00 p.m. In the minutes which followed the “Go” call, the first propellants began flowing into the engines’ fuel lines. The AJ-26s – which can trace their heritage back to the Soviet Union’s ill-fated N-1 lunar rocket – are fed by a refined form of rocket-grade kerosene (known as “RP-1”) and liquid oxygen.
The loading process was critically timed to begin about 90 minutes ahead of the scheduled launch, because of time limits associated with the rapid boil-off of the cryogenic propellants. Shortly after the beginning of fueling, the A-ONE team refined the launch time to within a 15-minute block, between 5:00-5:15 p.m. “Extending beyond the 5:15 p.m. deadline will result in an automatic scrub for the day,” explained the Tracker. “The reduced timeframe is because of the boiling-off of the [liquid oxygen]…after the completion of the tanking…15 minutes beyond the planned T-zero will result in too much LOX boiling-off to launch safely to the desired orbit.” During the fueling process, a helicopter spotted a fishing boat within the launch danger zone, but by 4:10 p.m. it had been escorted away.
The final polling of the launch team occurred in a two-step process, beginning shortly after 4:30 p.m., with the first confirmation of “Green across all stations”. At the same time, out at Pad 0A – as the effects of liquid oxygen boil-off became apparent, almost concealing Antares’ name at one stage – the final chill-down of the AJ-26 engines got underway to condition them for the ignition sequence. The 75-minute-long fueling process concluded at 4:45 p.m., with propellants at flight-ready levels, and at 4:48 p.m. the final “Go for Launch” was received from the A-ONE teams. Antares’ primary payload – a mass simulator for the Cygnus cargo craft – was transferred to internal power and at 4:51 p.m. the Transporter Erector Launcher (TEL) was armed to enable it to execute a rapid retraction from the vehicle the moment of liftoff. Five minutes before launch, the Flight Termination System was activated, enabling the ordnance which would destroy Antares in the event of a major malfunction or an off-nominal situation.
At 4:56:30 p.m. – when the clock reached T-3 minutes and 30 seconds – the ‘terminal count’ got underway, with the transfer of command to Antares’ autosequencer, which assumed primary control of all vehicle critical functions. Ignition of the twin AJ-26 engines commenced at T-2 seconds, with computer-controlled health checks conducted as they ramped up to full power. Each of these powerplants produces a sea-level thrust of 338,000 pounds and liftoff occurred at 5:00:02 p.m., with Antares clearing the tower five seconds later. Watched by several hundred spectators – including representatives of AmericaSpace – the vehicle immediately commenced a pitch and roll program maneuver, which established it onto the proper flight azimuth of 107.8 degrees.
Within 80 seconds, Antares passed through the period of maximum aerodynamic turbulence (nicknamed “Max Q”) and the AJ-26 engines continued to burn hot and hard, finally shutting down – as planned – a little under four minutes after launch. At 5:03:55 p.m., having reached an altitude of 66 miles, the first stage separated, and the vehicle coasted for almost two minutes, before the jettisoning of the bullet-like payload shroud at 5:05:19 p.m. and ignition of the solid-fueled Castor-30A second-stage engine at 5:05:28 p.m. The Castor engine, built by Alliant TechSystems, produced a thrust of 89,000 pounds and burned for two and a half minutes, providing the final impulse to inject the Cygnus mass simulator into a low-Earth orbit of 155-186 miles, inclined 51.6 degrees to the equator. A quartet of tiny picosatellites – three provided by NASA’s Ames Research Center of Moffett Field, Calif., to demonstrate the use of smartphones for CubeSat avionics, and an amateur-radio satellite – were deployed from a dispenser at 5:09 p.m.
The final key event for A-ONE occurred triumphantly at 5:10:03 p.m., when the 16.5-foot-long Cygnus mass simulator itself separated smoothly from the second stage and entered free flight. Equipped with instrumentation to gather data on the launch, ascent and orbital flight environments, the 8,400-pound simulator serves as a precursor to the demo mission of a ‘real’ Cygnus to the International Space Station, later this summer.
“Today’s successful test marks another significant milestone in NASA’s plan to rely on American companies to launch supplies and astronauts to the International Space Station, bringing this important work back to the United States where it belongs,” said NASA Administrator Charles Bolden. “Congratulations to Orbital Sciences and the NASA team that worked alongside them for the picture-perfect launch of the Antares rocket. In addition to providing further evidence that our strategic space exploration plan is moving forward, this test also inaugurates America’s newest spaceport capable of launching to the space station, opening up additional opportunities for commercial and government users.”
As described in AmericaSpace’s A-ONE preview article, the first flight of this new rocket has come at the end of a long and difficult road for Orbital Sciences, the Dulles, Va.-based aerospace company, which in December 2008 won a $1.9 billion slice of NASA’s Commercial Resupply Services (CRS) pie. The provisions of this contract require Orbital to transport upwards of 44,000 pounds of equipment, payloads and supplies to the International Space Station aboard eight missions of its Antares-boosted Cygnus cargo craft by 2016. However, efforts to configure the MARS site on Wallops Island for Antares operations have been mired with technical difficulty. As part of the redevelopment of the site, Pad 0A was completely demolished and a new complex was assembled with kerosene and liquid oxygen tankage for Antares. Problems with the cryogenic handling equipment and the completion of MARS conspired to delay the A-ONE mission by over a year.
However, today’s spectacular launch – nominal in all respects – may still place the company in a strong position to attempt an inaugural demo of the Cygnus craft to the space station “around mid-year”, with AmericaSpace’s Launch Tracker noting “late June or early July” for the mission. It will deliver 800 pounds of equipment and supplies to the sprawling international outpost. That flight will follow a rendezvous profile not dissimilar to the one followed by CRS competitor SpaceX’s Dragon ships: completing a series of incremental steps, over a two-day period, to bring it within range of the station’s 57-foot-long Canadarm2 robotic arm for grappling and berthing onto the Harmony node. Orbital’s current manifest shows an ambitious 2013 schedule for Antares: following the A-ONE launch, the Commercial Orbital Transportation Services (COTS) demo to the space station will occur in the summer, with the first dedicated CRS mission tentatively slated for September and, perhaps, CRS-2 in December.
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