The rocket stands tall on the launch pad

On December 7th, the Space God 5-551 carrier rocket of the United Launch Alliance Corporation carried out a launch mission for the US Space Forces at the Cape Canaveral Space Force Station, codenamed STP3. The main payload of this launch is the technology test satellite "Space Test Program Satellite" (STPSat) 6 under the US Department of Defense's "Space Test Program" (STP). The arrow also carries a satellite called "Rooster 1". The rocket ignited and took off at 5:19 Eastern Time (18:19 Beijing Time). Two satellites will be launched into a circular orbit slightly higher than the geostationary orbit, 36100 kilometers above the equator, 7 hours and 10 minutes after takeoff. During this period, the upper level requires 3 ignition operations. This will set a record for the time it takes for a United Launch Alliance rocket launch mission from takeoff to rocket separation.

The launch was originally scheduled for the early morning of December 5th, but was postponed due to the discovery of RP-1 kerosene propellant leakage in the ground storage system of the launch pad the night before. The Russian made RD-180 engine of the first stage of the Space God 5 uses kerosene and liquid oxygen propellants.

The United Launch Alliance was awarded the launch contract for the STP-3 mission in June 2017, with a contract amount of $191.1 million, after defeating the space exploration company. The bidding proposal of the space exploration company is for the Type 5 Falcon 9 rocket.

This launch is the 90th flight of the Space God 5 rocket. All 89 previous launches were successful, with only two having minor issues. The Space God 551 rocket is equipped with a 5-meter diameter fairing, 5 solid bundles, and a single engine Centaur upper stage. It is the most powerful model in the Space God 5 family and has been launched 11 times before.

STPSat-6 is built by Northrop Aerospace Systems (formerly Orbital ATK) using its high-end modular A-500 platform, with a designed working life of at least 8 years. According to reports, the platform was originally purchased by another US government agency (most likely the Defense Advanced Research Projects Agency (DARPA)) for a different geosynchronous orbit mission, but was transferred to the Space Test Program after that agency decided it was no longer needed.

The satellite carries a total of 9 payloads and experimental devices, with the main payload being the "Space and Atmospheric Explosion Reporting System" (SABRS) 3 of the National Nuclear Safety Administration, which is used for nuclear explosion detection and collecting space environment data, supplementing the nuclear explosion detectors on active GPS satellites. The satellite also carries other secondary payloads from the Space Test Program Office, National Nuclear Safety Administration, NASA, and other defense agencies, including NASA's Laser Communications Relay Verification (LCRD) payload. Another payload called "SENSER" is required to conduct space environment testing on some key technologies that are ready for production and will be used in the next generation system, in order to reduce the development risk of future nuclear explosion detection sensors.

The LCRD, which costs $320 million, will conduct a series of experiments over two years to test how to transmit bulk information faster than traditional wireless communication systems through the use of ground-based laser communication links. NASA officials stated that the validation goal is to demonstrate that the system's transmission speed can reach 10-100 times that of the current RF baseline system. NASA had previously verified optical communication directly to Earth from a lunar orbiter in 2013 and 2014, but due to the fact that laser payloads were not the main focus of that mission, testing time was limited at the time.

The LCRD project is led by NASA Goddard Space Flight Center and supported by Jet Propulsion Laboratory and MIT Lincoln Laboratory. It was originally planned to be carried on a commercial communication satellite built by Laura Space Systems (now Maxa) in 2016, but NASA later decided to switch to the military's STPSat-6 satellite. The delay of STPSat-6 has caused its launch time to drag on until now. If the laser terminal works well, NASA may convert the LCRD into practical use after the two-year main mission ends.

The Space Test Program aims to rapidly deploy and evaluate various space capabilities, in order to respond more quickly to constantly changing military needs. According to the announcement by the US Air Force in 2015, STPSat-6 will be deployed in a geostationary orbit between 80 and 120 degrees west longitude.

The Rooster program, also known as the Long Term Propulsion ESPA (LDPE), is a standardized satellite platform based on the Progressive Disposable Vehicle (EELV) Secondary Payload Adapter (ESPA). It has a standard interface and can carry multiple payloads with surplus capacity under any launch mission of the US National Security Space Launch (NSSL) program. Rooster 1 (LDPE-1) is also manufactured by Northrop Aerospace Systems, and its payload involves communication, space weather sensing, and sky perception technologies.

The United Launch Alliance announced that the launch of the Space God 5 will set several firsts, including the first use of a 5-meter composite fairing manufactured using non autoclave technology. This simpler carbon fiber curing process can save money, time, and weight. The fairing looks the same as the previous headgear of the Space God 5 and was also built by Swiss company Huage Aerospace, but the construction site is a newly built facility at the United Launch Alliance rocket factory in Decatur, Alabama. The previous fairing of Space God 5 was produced by Huage in Switzerland. The next generation Vulcan rocket from United Launch Alliance will also adopt this fairing design. The company hopes to obtain flight experience for the fairing before the "Fire God" test launch next year.

This flight also introduced a in-flight power supply system for the first time, which will provide power to two satellites during the long taxiing process, ensuring that the onboard battery is fully charged when the rocket separates. There is also a GPS enhanced navigation capability added to the arrow, which allows the upper stage of Centaurus to more accurately send satellites into predetermined orbits. A new rate gyroscope device with lower cost and lighter weight is also used on the arrow.

Source: Hang Xiaoyu