ULA’s Atlas V launches with the NROL-33 military spacecraft
A National Reconnaissance Office (NRO) military payload rode into orbit atop the United Launch Alliance (ULA) Atlas V rocket on Thursday. Liftoff of the NROL-33 mission from Cape Canaveral occurred at 09:09 local time (13:09 UTC) from Space Launch Complex -41 (SLC-41).
Atlas V Mission:
Like most missions for the National Reconnaissance Office, many details of Thursday’s launch – for instance the type of satellite being deployed and the rocket’s flight plan – were classified.
Launch hazard warnings and notices to airmen show that the rocket was to head East after liftoff, flying over the Atlantic. This suggests the Atlas will be targeting a geosynchronous transfer orbit, as this is the only low-inclination orbit regime typically used for NRO payloads of this size.
The most likely identity of the NROL-33 payload is a Quasar communications satellite. Used to relay data from other NRO satellites to ground stations, Quasar is also known as the Satellite Data System (SDS).
Speculation that the NROL-33 payload is part of the Satellite Data System is reinforced by the patches created to commemorate the launch. The payload patch features a pack of three wolves – before it was edited down for release – and a winged warrior emitting five beams of light from her outstretched hand, against the backdrop of a setting sun.
The wolves most likely denote the three newest satellites in the Quasar fleet, all of which operate in geosynchronous orbit. Five earlier satellites – two geosynchronous and three in elliptical Molniya orbits – have been identified as part of the same generation of satellites – these are presumably denoted by the beams.
A setting sun is usually employed to symbolise the final launch of a particular satellite, so presumably L-33 will be the last third-generation SDS.
The launch patch, meanwhile features a flying squirrel along with the motto “Defendi nostrae opes”, literally “to defend our resources”. The meaning of this is not entirely clear, however it could related to the fact that NROL-33 is intended to support the NRO’s reconnaissance fleet, and provide it with resources to return images for analysis. Europe is prominently featured on the insignia, which suggests the spacecraft is intended for use over that part of the world.
The patch also features eight stars, arranged in two banks of four on either side. While its meaning remains unclear, this symbol has appeared on several past Quasar patches.
The first Quasar satellite was OPS 7837, launched in June 1976 atop a Titan III(34)B. First-generation satellites were built by Hughes, based around a derivative of the HS-350 series of spacecraft. Six or seven were launched – due to similarities between early Quasar satellites and the contemporary Jumpseat signals intelligence spacecraft, modern analyses disagree about which spacecraft belonged to each series.
All of the first-generation satellites operated in Molniya orbit. A special, highly elliptical, regime, Molniya orbits have periods of twelve hours, and are inclined such that the orbits precess at the same rate with which the Earth rotates. resulting in the satellites reaching apogee over the same point on the Earth’s surface.
Second generation satellites, based upon Hughes’ HS-386 bus, were designed to be deployed from the Space Shuttle. Deployed with the aid of a perigee kick motor and an internal solid-fuelled apogee motor, the first three were flown aboard Shuttles with the fourth riding to orbit on a Titan IV.
It was this series which introduced a geosynchronous element, with the November 1990 launch of USA-67 aboard Atlantis on STS-38.
A Titan IV(405)A was used for what is generally considered to have been the final second-generation launch which took place in July 1996. In January 1998 an Atlas IIA lifted off on the NROL-5 mission, also known as Capricorn, carrying the first third generation spacecraft towards its Molniya orbit.
Capricorn was followed by NROL-10, or Ursa Major, in December 2000 and NROL-12, Aquila, in October 2001, using Atlas IIAS rockets. Both of these vehicles went into geosynchronous orbit. The next Molniya launch took place in August 2004, with the final Atlas IIAS conducting the NROL-1 mission.
The low number of this launch has never been explained, however it has been speculated that the original NROL-1 payload may have been cancelled and the designation reassigned.
Another possibility is that repeated problems with the satellite caused it to delayed – which could be alluded to by the NRO’s choice of the name “Nemesis” for the flight, rather than naming it after a star or constellation which was more usual for the era.
The most recent Molniya-orbit satellite to be launched was USA-198, also known as NROL-24 or Scorpius, which flew in December 2007. Launched atop an Atlas V 401, this satellite appeared to be the first in a series of replacements for the older satellites, however no more have been forthcoming.
The NROL-27 and NROL-38 missions of 2011 and 2012 replaced the two earlier geosynchronous satellites.
Since both geosynchronous satellites have been replaced in the last few years, it is unlikely that L-33 will replace an existing satellite.
It remains unclear whether it will serve as an on-orbit spare, or be used to open a new orbital slot for the constellation. It also remains to be seen whether the geosynchronous element of the constellation has now completely replaced the Molniya component, or whether these planes will be replenished in due course.
Thursday’s mission was conducted by United Launch Alliance, a joint venture of Lockheed Martin, who originally developed the Atlas V, and Boeing who brought the Delta II and Delta IV to the program.
The company, which was founded in December 2006, provides orbital launch services to US government agencies, including the US Air Force and NASA.
It is also responsible for commercial launches which are subcontracted from Lockheed Martin for the Atlas V and previously Boeing for the Delta II. No further commercial Delta II launches are currently manifested, with one vehicle left to be sold, while the Delta IV has not been offered to commercial users for some time.
The fourth Atlas launch of the year, Thursday’s mission made use of the 401 configuration. Designated AV-046, the Atlas consists of two stages; a Common Core Booster powered by an RD-180 engine, with an RL10A-4-2-powered Centaur atop it. The payload sits at the top of the rocket, encapsulated within a four-metre payload fairing.
The first stage’s RD-180 engine has recently been at the centre of a political dispute. Produced by Russia, the engine was developed from the RD-170 series used on the Zenit rocket.
This has attracted criticism due to the United States placing economic sanctions upon Russia over its recent intervention in Ukraine. Although a license to produce RD-180s in the United States does exist, at present all engines are imported from Russia.
A court recently issued an injunction, since overruled, blocking the import of these engines. Since no current US engine could easily replace the RD-180, should imports stop more permanently Atlas launches would slow or stop while a replacement was developed, leaving a significant gap in America’s launch capability.
The court ruling came as part of a case filed by SpaceX over a twenty-seven launch block-buy contract between the US Air Force and ULA. SpaceX feels that by buying launches up front in bulk the contract prevents it from bidding for these launches once its Falcon 9 vehicle is more established. The Air Force claims that by buying in bulk significant cost savings can be achieved.
The RD-180 is a liquid-fuelled engine which burns RP-1 propellant, oxidised by liquid oxygen. The Centaur’s RL10, by contrast, uses liquid hydrogen propellant and the same oxidiser.
For the NROL-33 mission, no solid rocket motors were required to boost the Atlas during the early stages of flight; depending on payload requirements, up to five Aerojet-build solids can be attached to provide additional thrust at liftoff, increasing the rocket’s payload capacity.
AV-046′s payload was protected during the early stages of flight by its fairing. Six different payload fairings are available for Atlas launches; three with diameters of four metres (13 feet), and three with diameters of five metres (16 ft).
Thursday’s launch used the four meter Long Payload Fairing (LPF), which at a length of 12.2 metres (40 feet) is the smallest of those available for the Atlas V. The LPF’s somewhat confusing name comes from its earlier use on the Atlas I, where it provided a longer alternative to the smaller and now long-discontinued Medium Payload Fairing.
While the precise flight plan for AV-046 is classified, it is likely to resemble past Atlas missions to geosynchronous transfer orbits.
All Atlas V missions begin with RD-180 ignition at T-2.7 seconds, with the engine building up thrust before lifting off at T+1.1 seconds.
Shortly after liftoff, AV-046 performed a roll manoeuvre to align itself along the required azimuth to achieve the necessary low-inclination orbit. Around eighty seconds into the mission, Atlas passed through the speed of sound, Mach 1, followed by the area of maximum dynamic pressure or Max-Q.
First stage flight concluded around four minutes and three seconds after liftoff, with the RD-180 being throttled back during the last few seconds of powered flight in order to keep the rocket’s acceleration at levels which won’t have caused damage to the vehicle or its payload.
Six seconds after cutoff, the spent Common Core Booster separated and the Centaur began its prestart sequence. RL10 ignition came ten seconds after the spent stage was jettisoned.
Around ten to twenty seconds into the second stage burn, the payload fairing separated from around AV-046′s payload.
The Centaur will likely make two burns, with their lengths dependent upon whether a standard or high-perigee transfer orbit is required. For a standard geosynchronous transfer orbit, the first burn will last around eleven minutes, with a four-minute second burn following a ten minute coast phase.
A mission to a higher-perigee orbit would see the first burn extended by around two minutes, with the second being cut to about 80 seconds after a much longer coast of around an hour and a half. Based on past Quasar launches, the standard profile is more likely.
Following spacecraft separation, NROL-33 will be given a USA designation – most likely USA-252 – and will manoeuvre to geosynchronous orbit under its own power.
The Centaur will make a further burn some time after separation, to deorbit itself. Reentry is expected to occur between 22:06 to 23:10 UTC over the Pacific, near Kwajalein in the Marshall Islands.
Thursday’s mission launched from Cape Canaveral’s Space Launch Complex 41. Originally a Titan launch pad, LC-41 was built along with the nearby Launch Complex 40 – now used by SpaceX’s Falcon 9 rocket – in the 1960s.
The two pads comprised the Integrate-Transfer-Launch (ITL) complex, with rockets being stacked vertically in a central integration building before rolling out to the pads for payload integration and launch.
The first launch from LC-41 occurred in December 1965, with a Titan IIIC lofting a pair of Lincoln Experimental Satellites. Ten Titan IIICs launched from LC-41 between 1965 and 1969, after which conversion work began to allow the pad to accommodate the Titan IIIE with its cryogenic upper stage.
The first Titan IIIE was launched in February 1974, but failed to achieve orbit. Following this, six successful launches deployed a pair of Helios spacecraft to investigate the Sun, the two Voyager probes which visited the outer planets, and the two Viking missions to Mars.
In 1989 the Titan IV made its maiden flight from LC-41, carrying a Defense Support Program missile detection satellite. It was the first of ten Titan IVs to fly from LC-41, which was renamed Space Launch Complex 41 around 1997.
The last two Titan launches from the pad both failed, forming part of the run of three consecutive failures suffered by the Titan IV in 1998 and 1999. The first of these resulted in the loss of NROL-7, a Mercury signals intelligence satellite, whilst the second was carrying a DSP satellite.
Four years after its last Titan launch, conversion of the pad for the Atlas V had been completed, with both the fixed and mobile service towers demolished in favour of a clean-pad approach.
A new, dedicated, Vertical Integration Facility – located half a kilometre (0.34 miles) from the pad – replaced the earlier Vertical Integration Building which had served both of the ITL pads. AV-046 will be the thirty-eighth Atlas to launch from SLC-41, and the sixty-fifth rocket overall.
The launch of NROL-33 was the ninth to be conducted by the United States this year. The next launch from Cape Canaveral will be a SpaceX Falcon 9 carrying six Orbcomm satellites, which is scheduled for next month.
That mission had been expected to go earlier in the month, however it was delayed due to a problem with the vehicle discovered during its practise countdown.
The next scheduled Atlas V launch is planned for July, with an Atlas V 401 deploying the GPS IIF-7 navigation satellite.
Before that, United Launch Alliance will next be in action launching NASA’s Orbiting Climate Observatory 2 (OCO-2) mission atop a Delta II in early July.
(Images via ULA, L2 and Jacques van Oene/Spacepatches.nl)