The United Launch Alliance’s Atlas V rocket has performed its twenty-fifth launch, delivering into orbit the classified NROL-34 payload for the US National Reconnaissance Office. The launch took place from Vandenberg Air Force Base in California at 04:24 UTC Friday (21:24 local time Thursday).
Atlas V Launch:
The launch was performed by AV-027, an Atlas V 411 which was named “Frigga” by its launch team. The launch itself was named “Odin”. The Atlas V 411 configuration features a payload fairing with a diameter of four metres, a single solid rocket motor, and a single-engined Centaur upper stage. It was the third Atlas V to fly in this configuration, the fourth Atlas V to launch from Vandenberg, and the twenty-fifth Atlas V to launch since the type’s maiden flight nine years ago.
The first stage of the Atlas V is a Common Core Booster (CCB), which contains RP-1 propellant and liquid oxygen oxidiser. These are used to fuel a single RD-180 engine which powers the rocket for the first four minutes of flight. The Centaur upper stage is fuelled by liquid hydrogen and oxygen, and powered by a single RL10. The payload is mounted atop the second stage via an adaptor, and is enclosed in the payload fairing.
Six payload fairings are available for Atlas V launches; three four metre fairings and three five metre fairings. The four metre fairings are the Large Payload Fairing (LPF), Extended Payload Fairing (EPF) and Extra Extended Payload Fairing (XEPF). The 12.2 metre long Large Payload Fairing was originally developed as an optional larger fairing for Atlas I and later Atlas II rockets. It was first used for the launch of CRRES in July 1990.
As payload sizes continued to increase, the LPF gradually became the standard fairing for Atlas rockets, and the EPF was developed for larger satellites. It consists of an LPF whose cylindrical section has been lengthened by 90 centimetres. The EPF was first used on the Atlas II in the 1990s. The XEPF is the longest of the three four metre fairings, and is a further 90 centimetres longer than the EPF.
It was developed for the Atlas V and was first used for the launch of Inmarsat-4 F1 in March 2005. The EPF was used for the launch of NROL-34.
NROL-34 was the eighth NRO spacecraft to be launched in the last seven months. Since last September six major satellites and two CubeSats have been launched for the National Reconnaissance Office. The first of these eight satellites, USA-215 or NROL-41, was launched on 21 September 2010 by an Atlas V 501 flying from the same pad that that was used for NROL-34.
It entered a retrograde low Earth orbit at an inclination mirroring the prograde orbits of Lacrosse radar imaging satellites. It is believed to be the first in a new generation of radar imaging spacecraft developed as part of the Future Imagery Architecture programme.
On 21 November last year, a Delta IV Heavy launched the USA-223 satellite under the designation NROL-32. This launch saw the spacecraft, a Mentor electronic signals intelligence satellite, deployed into a geosynchronous orbit.
Then in December a Falcon 9 deployed the QbX-1 and QbX-2 technology demonstration satellites: a pair of three-unit CubeSats which were operated as part of the Colony-1 programme. These satellites remained in orbit for only a month; decaying from orbit on 6 and 16 January 2011 respectively.
On 20 January this year, USA-224 or NROL-49 was launched by a Delta IV Heavy. A KH-11 “Improved Crystal” electro-optical reconnaissance satellite, USA-224 was deployed into a sun-synchronous low Earth orbit. This was followed on 6 February by a Minotaur I deploying USA-225 (NROL-66), a larger technology demonstration satellite also known as the Rapid Pathfinder Program (RPP).
The most recent NRO launch to date occurred on 11 March, when a Delta IV-M+(4,2) deployed USA-227 as part of the NROL-27 mission. USA-227 was deployed into a geosynchronous transfer orbit, and has since raised itself into a geosynchronous orbit. In early April amateur observers located it at a longitude of 30.4 degrees west, and detected signals from it consistent with a Satellite Data System (SDS) communications satellite.
As is typical for NRO launches, no details of the payload or flight plan for the NROL-34 mission were disclosed. This said, the fact that it is launching from Vandenberg rather than Cape Canaveral rules out low-inclination trajectories such as geosynchronous orbits. The use of the Atlas V 411 configuration means that some smaller payloads can be eliminated.
Based upon this, it was widely speculated before launch that the payload would be an electronic signals intelligence (ELINT) satellite bound for a highly elliptical Molniya orbit. The NRO has used ELINT satellites in such orbits since the Jumpseat programme in the early 1970s, with the Jumpseat programme. In the mid 1990s, Jumpseat was replaced by a new series of three satellites known as “Trumpet”, and this was followed in 2006 by a new series of satellites. The name of the new programme is not known, and it is generally identified by observers as “Advanced Trumpet”, “Improved Trumpet” or “Trumpet Follow-On”.
Shortly before launch, however, hazard areas published by the United States Air Force suggested that the launch would not be going to a Molniya orbit, but to an orbit at around 63 degrees inclination. Low Earth orbits at this inclination have been used for satellites which form part of the Naval Ocean Surveillance System (NOSS). These satellites operate in pairs which are launched together, and used to locate and track ships from their radio communications.
It is unclear whether the satellites deployed by NROL-34 are part of the current generation of NOSS satellites, or the first in a new generation. Since 2001 the third generation of NOSS spacecraft has been in service.
First-generation NOSS satellites, also identified as “White Cloud” and “PARCAE”, were launched between 1976 and 1987. They were launched and operated in groups of three known as triads. The first four launches used Atlas E/F rockets with MSD upper stages, and the next five used Atlas H rockets, also with MSD upper stages. The MSD, or Multiple Satellite Dispenser, was an upper stage designed to deploy NOSS satellites, and consisted of an FW-4D engine, attachments for the three spacecraft, and a detachable plume shield. On three missions, instruments were mounted upon the plume shield to perform research in orbit, under the LIPS programme.
The first launch of NOSS satellites occurred on 30 April 1976, with the OPS 6431 spacecraft being placed into orbit. This was followed by OPS 8281 in December 1977 and OPS 7245 in March 1980. The launch of the fourth triad of satellites, OPS 3255, occurred in December 1980 and ended in failure. It was the last NOSS launch to use the Atlas E/F. Two tenths of a second before its scheduled shutdown one of the rocket’s two LR-89-5 booster engines failed due to insufficient lubrication. The rocket pivoted through 180 degrees before the rotation stopped. The rocket continued to fly backwards for several minutes before exploding. All four Atlas E/F launches were made from Space Launch Complex 3W at Vandenberg.
Launches resumed in February 1983 when OPS-0252 was deployed by the first Atlas H rocket. The Atlas H was only used for NOSS launches, and launched all of the remaining first-generation satellites. All five flew from Space Launch Complex 3E, the same launch pad used for NROL-34. The sixth triad, OPS 6432, was launched in June 1983, followed by OPS 8737 in February 1984.
The next NOSS launch occurred on 9 February 1986, and was the first to use the USA numbering sequence rather than the older OPS system. Unlike previous launches where all objects from the same launch were given a single cover-all designation, each individual spacecraft was given its own designation. For the February 1986 launch, the dispenser was designated USA-15, with the three satellites being designated USA-16, USA-17 and USA-18. This pattern was repeated with the final launch in May 1987, when the MSD was designated USA-22 with the satellites being named USA-23 to 25.
Second generation NOSS spacecraft, also known as “Ranger”, were launched by Titan IV rockets equipped with SLDCOM dispensers. After deploying the payload, the SLDCOM spacecraft raised themselves into medium Earth orbits and were used as communications satellites. As with the first-generation spacecraft, the NOSS spacecraft were launched in threes.
The first launch of the second generation system occurred in June 1990, when a Titan IV(405)A deployed the SLDCOM USA-59 and three NOSS satellites; USA-60 to 62. Subsequent launches used Titan IV(403)A rockets, the next of which occurred on 8 November 1991. It deployed the second SLDCOM, USA-72, as well as NOSS satellites USA-74, 76 and 77.
On 2 August 1993, the attempted launch of the third triad of second generation satellites failed to achieve orbit, exploding shortly after liftoff from Vandenberg. An investigation found that one of the rocket’s solid motors had been damaged during maintenance, leading to the explosion 101 seconds into its flight. A final triad was launched on 12 May 1996, with USA-122 being the SLDCOM and USA-120 to 122 the NOSS spacecraft.
Third generation satellites operate in pairs, as was discovered after the first launch, which occurred on 8 September 2001 when an Atlas IIAS deployed the USA-160 (NROL-13) spacecraft. At first it was assumed that a third satellite had been launched, but had failed to separate from either the rocket or one of the other spacecraft. The second launch, NROL-18, deployed USA-173 in December 2003, and when again only two satellites were identified it proved that the number of spacecraft per launch had been decreased. The United States Air Force has returned to assigning a single designation to each pair of spacecraft, with the second spacecraft being officially catalogued as debris.
The third launch was NROL-23, which used an Atlas IIIB and was the final flight from Space Launch Complex 36 at Cape Canaveral. It occurred on 3 February 2005, and placed USA-181 into orbit. On 15 June 2007 an Atlas V 401 launched USA-194 (NROL-30); the fourth pair of third-generation spacecraft. During a long coast phase between burns, a valve on the upper stage of the rocket failed to close properly. This resulted in a propellant leak and the rocket running out of fuel four seconds before the scheduled end of its second burn, leaving the spacecraft in a lower than planned orbit. The satellites remained attached to each other longer than usual, and used their own propulsion systems to correct their orbits, probably at a significant cost to their operational lives.
Given the use of the 401 configuration for the previous launch, several theories have developed to explain why an Atlas V 411 was required for NROL-34. An early theory was that a third satellite may be present on the rocket; either a technology demonstrator or a replacement for an older NOSS satellite. This has since been disproven as amateur observers have only identified two satellites as having been deployed by the rocket.
It is possible that this represents the first launch of a new generation of satellites, which may be heavier than their predecessors thus necessitating the use of the booster. Another theory which is gaining much credence is that the booster was added in order to simplify and shorten the flight profile of the rocket. The previous NOSS launches required a long coast phase followed by a second burn of the upper stage engine, however the length of this coast phase contributed to the partial failure of the launch of USA-194.
The Atlas V can fly one of two different flight profiles to reach low Earth orbit; either a single burn direct ascent, or a two burn profile as with USA-194. Since NOSS satellites orbit at an altitude of around 1000 kilometres, an extended coast phase is required. The single burn profile is less efficient, providing less payload capacity, however the shorter flight and lower number of burns reduces the chances of a failure.
The Centaur for the NROL-34 launch was not painted white like that used to launch USA-194. This suggests that it was not intended to fly an extended mission, and hence that a single burn ascent would be used. Since this profile was not used on the previous launch, it is probable that the mass of NOSS satellites is too great to be launched by the 401 configuration using the less efficient single-burn ascent profile, however the shortfall can be addressed by adding a single booster. Until January, NROL-34 was publically manifested to launch on an Atlas V 401, which was originally assumed to have been an error in the manifest, however it is possible that the configuration was changed after the launch had been manifested in order to use a single-burn flight profile.
No information concerning the flight profile for the NROL-34 launch was made publically available. That said, many of the flight milestones occur at similar times in any launch. As with all Atlas V launches, the first stage RD-180 engine ignited 2.7 seconds before launch. The solid rocket motor ignited and Frigga lifted off at T+1.1 seconds, beginning a series of roll and yaw manoeuvres to align itself for the correct ascent trajectory. Around a minute after launch the rocket experienced maximum aerodynamic pressure as it approached the sound barrier; becoming supersonic at around 65 seconds after liftoff.
About 95 seconds into flight the SRM burned out, and forty seven seconds later it was jettisoned. The delay between burnout and jettison was due to constraints because of the vehicle’s flight dynamics, and the rocket overflying areas where boosters cannot be dropped, such as oil rigs.
A little over four minutes after launch, the RD-180 engine completed its burn and shut down. Six seconds later the first stage was jettisoned. The Centaur ignited ten seconds after staging, and a little under ten seconds later the payload fairing separated from around the satellite. A few seconds later, four minutes and forty four seconds after launch, official updates on the status of the launch were terminated, and no further information was released other than a press release reporting the success of the launch.
Assuming that a single-burn insertion profile was indeed used, the Centaur will have made one long burn up to twelve minutes in duration. Shortly after the completion of these burns the spacecraft separated from the rocket. The Centaur subsequently reoriented and deorbited itself into the
Upon reaching orbit, one of the satellites deployed by NROL-34 was given the designation USA-229; part of a system of standardised designations for US military spacecraft which has been used since 1984. These designations have been assigned sequentially in recent years, and the use of USA-229 comes after the designation USA-228 was inexplicably assigned to a civilian spacecraft; the University of Texas’ FASTRAC-2 “Emma” satellite. The second satellite is officially reported to be debris from USA-229, and as such has not been named.
Frigga launched from Space Launch Complex 3E (SLC-3E) at Vandenberg Air Force Base in California. Originally built as Launch Complex 1-2 of the Point Arguello Naval Air Station, SLC-3E was first used for the launch of an Atlas-Agena with the Midas 3 satellite in July 1961. In 1964 it became part of Vandenberg Air Force Base, and was identified as Point Arguello Launch Complex 1-2 (PALC-1-2) until acquiring its current name in 1966.
SLC-3E was used for Atlas-Agena launches until October 1966, after which it was used by a trio of Atlas SLV-3 rockets launching X-23A PRIME spacecraft onto suborbital trajectories, and for the only flight of the Atlas SLV-3 Burner II, a mission which failed to place a large number of satellites into orbit.
No launches occurred from SLC-3E between 1969 and 1977. Between 1978 and 1981 seven prototype GPS satellites were launched by Atlas E/F rockets from SLC-3E, after which the complex supported the Atlas H rocket for all five of its launches, each deploying three NOSS satellites. The complex supported its final Atlas H launch in 1987, and in 1992 renovation began to enable Atlas II launches from the pad. This work was completed in 1996, and preparations began in 1997 for the first Atlas IIAS launch from Vandenberg, carrying the Terra satellite. Following almost two years of delays, this launch finally took place in late 1999.
Two further Atlas IIAS launches were made from the SLC-3E, both carrying pairs of NOSS satellites. The complex was then converted again, this time to accommodate the Atlas V, which first flew from Vandenberg in March 2008. Frigga was the fourth Atlas V to launch from SLC-3E.
The launch of NROL-34 was the fifteenth orbital launch attempt of 2011, and the fourteenth to reach orbit. It was the second Atlas V launch of the year, and the fourth EELV. The next Atlas V launch is scheduled for 5 May, when the SBIRS-GEO 1 satellite will fly atop an Atlas V 401 from Cape Canaveral. Later in the year, Atlas V rockets will also deploy the Juno and Curiosity probes to Jupiter and Mars respectively, and United Launch Alliance list a GPS launch as “on standby” for late December.
(Images via Pat Corkery, ULA, SpaceX)