The launch involving the first SBIRS Geosynchronous Orbit satellite GEO-1 satellite took place Saturday May 7th, 2011 from Space Launch Complex 41 at 2:10 pm EDT. The Space-Based Infra Red System (SBIRS) consists of a coordinated network of space-based satellites providing missile warning/detection and defense functions aggregating coverage capability on the entire global aerial battle space. The GEO-1 would employ a array of infra red sensors to capture the heat signature of missiles from its 19,323 miles (35,786 kilometers) apogee orbit altitude. This launch comforts the United Launch Alliance to a 100% success rate on fifty consecutive launches. The Boeing/Lockheed Martin alliance began operating in December 2006 offering commercial launch contracts through Lockheed Martin Commercial Launch Services (wholly owned by Lockheed Martin corp) while allowing the US Government to interact directly with United Launch Services LLC (the contract agent for parent holding company United Launch Alliance). The United Launch Alliance was formed in December of 2006 allowing Boeing and Lockheed Martin to consolidate space launch operations and efficiently support any type of payload and orbital trajectory requirements for specific programs.
The Atlas V family of launch vehicles whom the Atlas V 401 variant successfully launched Saturday belongs to, has accounted for 26 successful launches to date since being first introduced in 2002. The family of launch vehicle products offered by ULA also comprises the Delta IV first introduced in 2002, using a Pratt & Whitney RS-68 first-stage engine as the designated option for high-priority USAF, National Reconnaissance Office, NASA and commercial higher payload using fairings ranging from 165 in. (4.2 m) to 275 in (7 m) in diameter. The Delta II ‘legacy’ launch vehicle family has also been available since in 1989. The delta II has carried a sizable proportion of the US Air Force GPS satellites into orbit as well as fulfilling the requirements of additional customers like the NRO, DARPA (Defense Advanced Research projects), Missile Defense Agency (MDA), NASA and other various commercial organizations requiring the 10 ft-diameter payload fairings provided by the Delta II.
The Atlas V in operation
The Atlas V is a modular family of space launch vehicles first introduced in August 2002 operating out of Cape Canaveral Space Launch Complex 41, Florida and Space Launch Complex 3E at Vandenberg Air Force Base ,California on 24-month integration-launch cycle. The two main variants Atlas V400 and Atlas V500 provide a flexible approach to mission configuration using a modular design to adapt with the contracting organization’s payload requirement. As a result each of the V400 and V500 variant is able to offer three different payload configurations. More than through various payload accommodation, the Atlas V family directly interchangeably shares engines and major components that across different variants; the common multi stage propulsion sub-systems consist of the Centaur engine, the main lower stage Atlas rocket booster along with complementary Solid Rocket Boosters (SRB). Additionally various component and parts provide the stage interconnection and hardware interfacing required for elements to be seamlessly integrated across both Atlas V variants; specific payload adapters to which are mounted the payload separation system along with spacecraft electrical interface to the launch vehicle, spacecraft purge system connections and instrumentation, Centaur Forward Adapter, Centaur Aft Adapter, Centaur Aft Stub Adapter , 400 Series Interstage Adapter, etc…
The adaptable flexible Payload Fairings (PLF) Approach
The payload is the critical factor for determining a suitable payload fairing as well as assigning a designated mission configuration to a customer during mission planning. As a result the Atlas V400 family introduces three different Payload Fairings (PLF) size of similar diameter but with varying length designating Large, Extended and Extra Extended LPF, EPF, XEPF requirement respectively. The 165.4 in. (4.2 m)-diameter Payload Fairings can have length varying from 472.4 in (12.0 m) to 543.3 in. (13.8 m). This approach results in the V400 series ideally providing an available payload value between 4,689 lbs (2,127 kg) and 5,483 lbs (2,487 kg). In a similar fashion the V500 family offers distinctly more available payload on its three different Payload Fairings with a fixed-diameter of 213 in. (5.4 m). The Short ,Medium and Long versions (respectively 815 in., 921 in. and 1043 in. -or- 20.7 m, 23.4 m and 26.5 m) identify the varying length. In all the V500 family can accommodate payloads that are heavier by a magnitude of almost two (7,769 lbs to 9,654 lbs) in comparison to the V 400 family of launch vehicles.
The Propulsion System
1.The common Centaur Engine
The Centaur engine provides additional thrust during low and intermediate orbit transition using a single or a dual engine configuration employing one or two restartable Pratt & Whitney RL 10A-4-2 engines. The Centaur size is 120 in. (3.05 m) in diameter and 499 in. (12.68 m) in length.
The Single Engine Centaur (SEC) operation provides operation at thrust level of 22,300 lbf (99.2 kN), using one 20 in. (51 cm) electromechanically actuated nozzle. The Dual Engine Centaur (DEC) option delivers thrust of 44,600 lbf (198.4 kN) across two electromechanically actuated nozzles.
The Solid Rocket Boosters (SRB)
The Solid Rocket Boosters are the most visible artifacts of the Atlas V program modularity concept as up to three SRB can be attached externally to the V400, while the V500 can receive up to five extra boosters.
Their overall dimensions are 62.2 in. (158 cm) in diameter and 787 in. (20 m) in length permitting the Nose fairings to house additional instrumentation. They can provide 1688.4 kN (379,550 lbf) of additional thrust each.
The standard Atlas Booster or Common Core Booster
The main Atlas heavy lift booster relies on the Pratt & Whitney/NPO Energomash RD-180 booster engine burning liquid oxygen and RP-1 propellant to deliver a vacuum thrust performance of 933,369 lbf (4,152 kN).
Its pressurization system uses helium for tank pressurization and requires a dedicated computer controlled pressurization system. The RD-180 is responsible for powering the vehicle’s ascent to atmosphere until the almost complete exhaustion of propellant is reached. At that point a low-level sensor propellant sensor activates the cutoff sequence.
A Logical Numbering Scheme
Given the various configuration options available, a very simple logical numbering format has been established to identify the Atlas V specific configuration be enumerating the Payload fairings size, number of Solid Rocket Booster attached to the launch vehicle and the number of Centaur engines. The Atlas V-xyz is a simple three-digits sequence such as Atlas V-401, Atlas V-402, Atlas V-552. On those numbers the first digit is a 4 or a 5 betraying a 4-meter or a 5-meter diameter fairing used. The second digit in the 400 or 500 sequence gives the number of Solid Rocket Boosters on the flight (from 0 to 3 on the -400 family, and from 0 to 5 on the -500 family) for instance we can have V411, V421 and V431 betraying 1,2,3 Solid rocket Boosters. differentiating the single engine Centaur from the dual engine Centaur. Finally the last digit differentiates the use of a single or dual engine configuration for the Centaur rocket (1 or 2 are the possible digit choices). Looking at the Atlas V401 launched on May 7th,a 4-meter diameter fairing was used, no Solid Rocket Booster was attached to the launch vehicle and a single engined Centaur configuration was in place.
The Geosynchronous Orbit GEO-1 Satellite
Depending on the mission assigned operational Geo-stationary Transfer Orbit profiles, we can derive that the GEO-1 overall payload falls below the 10,470 lbs (4,750 kg) threshold.
According to Northrop Grumman the SBIRS first Geosynchronous Orbit GEO-1 integrates both a scanning and staring main sensors with the scanning sensor designed for “continuous observation and surveillance of traditional intercontinental ballistic missile threats” and the staring sensor accomplishing the “detection of very low signature, short-burn-duration theater missiles”. It has a two-focal plane presenting more than one million detector elements. Northrop Grumman delivered the first integrated GEO-1 payload to Lockheed Martin for final system level testing on August 6th 2007.Prior to the May 7th 2011 final launch, the SBIRS program reached full pre-launch milestone March 3rd , 2011 when the Air Force was able to deliver the GEO-1 payload at Cape Canaveral Space Launch Complex 41. A Boeing C-5 Galaxy had ferried the sensitive GEO-1 satellite payload in its shipping container from the Lockheed Martin Satellite Integration Facility in Sunnyvale, California. This step was immediately followed by the satellite being integrated to the Atlas V booster initially due to launch on May 6th, but finally postponed to May 7th due to unfavorable weather.