A baker’s dozen of satellites – including a critical $1.3 billion sentinel for the National Reconnaissance Office (NRO), designed to electronically monitor worldwide military and civilian shipping – have been forced to wait for launch until 14 August, following a range instrumentation problem which scrubbed yesterday’s attempt with only minutes remaining on the clock. United Launch Alliance’s mighty Atlas V booster was fully fuelled and waiting out an extended hold in the final stages of the countdown, when, despite acceptable weather conditions at Vandenberg Air Force Base in California, the range remained ‘Red’, indicative of a ‘No-Go’ status for launch. Hopes were kindled to make a second attempt this morning (Friday) or early tomorrow (Saturday), but despite technicians’ best efforts these have ultimately proven fruitless.
For those watching NROL-36, it seemed at first that the countdown was charmed. Foggy conditions and a mere quarter-mile visibility, together with a solid marine layer at ground level extending to 600 feet and high cirrus clouds at 25,000 feet, were not expected to conspire against the launch of the Atlas, which will fly in its ‘401’ configuration: consisting of a Common Core Booster with 4-metre (13-foot) payload fairing, no strap-on rockets and a single-engine Centaur upper stage. Nicknamed ‘Rosie’, the vehicle is equipped with an Extended Payload Fairing, the second-largest in the Atlas V’s inventory of three 4-metre fairing types. In recent months, this fact alone forged speculation that the classified mission might launch a Satellite Data Systems (SDS) military communications payload.
In recent days, however, details have emerged from the intelligence community that NROL-36 actually comprises a pair of NRO Ocean Surveillance Satellites (NOSS), to be positioned in high-inclination orbit at an altitude of around 1,100 miles to constantly track every warship, all commercial shipping and large private vessels. The satellites are operated by the US Navy. In the early days of NOSS, they functioned in threes – known as ‘Triads’ – but the present third-generation satellites (first launched in September 2001) work in pairs, using interferometry to detect radio transmissions from ships and locate them on the surface using the Time Difference of Arrival technique. NROL-36 represents the sixth launch in the third-generation NOSS series and its official mission patch – bearing a fearsome bull and the legend ‘Freedom’s Shield and Hope’ – underlines its inherent importance.
The Atlas V boasts an almost impeccable success rate; in more than 30 launches over the last ten years, it has never failed to complete a mission. On one occasion, in June 2007, it experienced an anomaly with its Centaur upper stage, which left a NOSS payload in a lower-than-planned orbit, but the NRO still categorised the mission as a success. On the afternoon of 1 August 2012, therefore, it was with great expectations of similar glory that technicians tended to the giant 19-story booster. By 5:00 pm PDT, the countdown clock began ticking towards a scheduled liftoff at 12:40 am the following morning. As the evening wore on, preparations ran like clockwork: the first stage and the Centaur were powered-up, the Mobile Service Tower was rolled clear of the vehicle and parked by 9:00 pm, guidance system checks were completed and the laborious fuelling of the Centaur with 4,300 gallons of liquid oxygen commenced.
Late in the evening, a slight adjustment moved T-zero back to 12:44:30 am and, in order to properly ‘synch’ with this new launch time, a planned ten-minute hold in the countdown at T-4 minutes was extended by an additional four minutes. Shortly after 11:06 pm, loading of the Atlas’ first stage with liquid oxygen transitioned from ‘slow-fill’ to ‘fast-fill’ mode and by 11:17 pm the oxidiser aboard the Centaur reached its required flight level. An hour later, at 12:31 am – by now inside the 14-minute built-in hold at T-4 minutes – United Launch Alliance reported that range instrumentation assets were listed as ‘Red’, indicative of a ‘No-Go’ for launch. The clock would not resume until the problem was resolved.
As 12:44:30 am came and went, the clock remained halted at T-4.
Ten minutes later, a T-zero of 1:10:29 am was set. It now seemed unlikely that the issue would be rectified in time, for officials had earlier announced to mariners that launch would not occur after 1:30 am. By the turn of the hour, the range remained ‘Red’ and at 1:04 am the attempt was scrubbed. Within a quarter of an hour, the process of draining the Atlas’ liquid oxygen and liquid hydrogen propellants got underway and launch was tentatively rescheduled for 12:27 am on 3 August, with a 90-percent chance of acceptable weather. Unfortunately, as the day wore on, it was revealed that another delay, until no earlier than 12:13 am on the 4th, was unavoidable. It was subsequently announced that NROL-36 would remain on the ground until at least 14 August.
Military officials have been quick to stress that no issues exist with either the payload or the Atlas itself. Based on previous experience, the first stage’s Russian-built RD-180 engine, fed by RP-1 and liquid oxygen, will ignite 2.7 seconds ahead of liftoff, reaching full power when the countdown clock touches zero and climb-out will begin at T+1.1 seconds. Rising from Vandenberg’s storied Space Launch Complex-3 East (SLC-3E), propelled by almost a million pounds of rocket engine thrust, it will be the latest launch from a pad whose heritage dates back to the early 1960s. SLC-3E was historically used by Atlas and Thor rockets and was extensively overhauled in 2003-2005 to serve the Atlas V, after plans to build a pair of Delta IV pads were put on hold. The modifications included a 30-foot increase in the height of the Mobile Service Tower to a total 239 feet, an expanded exhaust duct, significant ambient and cryogenic fluid improvements and extensive refurbishments to communications and launch control facilities.
When NROL-36 finally flies, its Atlas will follow a south-south-easterly heading, with the first stage burning out after four minutes and three seconds. Slightly ahead of engine cut-off, the RD-180 will be throttled back to limit the acceleration and, after separation, it will be the turn of the Centaur upper stage. Fuelled by liquid oxygen and liquid hydrogen, the latter will burn for more than 14 minutes, after which it will coast for about an hour, then perform a second burn, lasting a minute or so, to achieve the required orbit for NROL-36. Shortly thereafter, the twin satellites will be deployed and it seems likely that a pair of additional Centaur burns will be needed to lower the orbit in order to support the release of eleven miniaturised, low-cost satellites, known as ‘CubeSats’.
These satellites – about the size and dimension of a Rubik’s cube, weighing no more than 22 pounds – are provided through NASA’s Educational Launch of Nanosatellites (ELaNa) and NRO’s Mission Support Directorate. Four of them come under the ELaNa umbrella: the University of California at Berkeley’s CubeSat for Ion, Neutral, Electron, Magnetic Fields (CINEMA), the University of Colorado at Boulder’s Colorado Student Space Weather Experiment (CSSWE), Morehead State University’s Cosmic X-ray Background Nanosat (CXBN) and Colorado Polytechnic University’s CP-5. The others – ‘Aeneas’ for the University of Southern California, a pair of satellites for the Army’s Space and Missile Defense Command (SMDC, dubbed ‘Able’ and ‘Baker’), the Space-based Telescopes for Actionable Refinement of Ephemeris (STARE) and a trio of ‘AeroCubes’ – have been funded by the NRO or other elements of the US military.
In order to deploy these satellites into their required 300 x 475-statute-mile orbits, eight dispensers are attached to the aft section of the Centaur upper stage, via an Aft Bulkhead Carrier, which is making its first mission. The scientific and technological objectives of these tiny satellites are many and varied. CINEMA will employ two instruments to provide cutting-edge measurements of the magnetosphere, including the precipitation of charged particles and auroral ions and electrons. CSSWE carries an energetic particle telescope, designed to monitor the interaction between solar energetic protons and the electrons of Earth’s radiation belts, as part of ongoing efforts to understand and predict ‘space weather’. Observations of the cosmic X-ray background are the primary task of CXBN, whilst CP-5 will evaluate a novel concept for a deployable thin-film mechanism to de-orbit satellites. The film consists of a miniature solar sail, whose characteristics and effect upon altitude and velocity degradation will be closely monitored from the ground.
Turning to the military experiments, Aeneas has been built in conjunction with the Department of Homeland Security and will test a 20-inch mesh antenna to track electronic tags on shipping containers in the open ocean. The Able and Baker duo are part of an Army experimental communications system, whilst STARE – also known as ‘Re’, in honour of the ancient Egyptian sun god – will be used for the optical tracking of space debris. Finally the AeroCubes will demonstrate a variety of new technologies, including deployable solar panels, ‘parachute-like’ devices for de-orbiting themselves and a closed-loop attitude-control system based on a three-axis gyroscope.