Space A Mission Pre-Launch Sequence

This is an overview of how a mission is passing from the test phase to the launch day. Delays -and or procedures- may have to be adjusted function of missions

Tests at the Goddard Space Flight Center Processing At or Near the Launch Center

What About the Launcher?

Tests at the Goddard Space Flight Center

About 4½ months before the launch date the spacecraft integration is considered completed. The spacecraft has been assembled from the various subsystems and science experiments. It enters its test phase which is to last about two months and a half at NASA's Goddard Space Flight Center. Such tests are aiming to verify that the craft is able to sustain the harsh environment it will meet in deep space. Alternate locations for the test may be, for example, at the Naval Research Laboratory (NRL) in Washington. Another concept may be that some part of the tests are proceded with a the very location of the main manufacturer and integrator

Processing At or Near the Launch Center

a spacecraft enclosed in its fairing at the VIB of launch pad 37, Kennedy Space Center, Fla. picture NASA

Once the testing phase completed and successfull, the craft is brought via a cargo-plane near the launch center where its launcher is going to liftoff from. That means the Astrotech Space Operations processing facility, Titusville, Fla (or the Payload Hazardous Servicing Facility -PHSF) for a launch from Kennedy Space Center, or the Astrotech Payload Processing Facility for a launch from Vandenberg AFB. Such facilities are the locations where the mission is prepared for launch and flight, as the spacecraft is further tested in preparation for these phases. The operations are beginning about 2 months before launch. The spacecraft's power, communications (like the ability to communicate through NASA's Deep Space Network tracking stations), and control systems are checked. Thermal blankets are attached as are solar arrays, which are tested and stowed, along with the high gain communications antenna. Science instruments are tested too. The propellant (hydrazine fuel) used for maneuvers and/or for the orbit insertion maneuver are further loaded, as spin tests are performed (spin tests are due to that a spacecraft, in the last moments before orbit or insertion on its path to a planetary journey, may be stabilized via having the launcher's last stage-craft stack rotating)
The spacecraft is eventually mated atop the upper stage, that is, for deep space missions, the stage which is to boost the mission unto its trajectory. This is done in the Vertical Integration Facility (VIF), a gantry-like, moveable structure located at the launch pad. The spacecraft-upper stage stack is transported to the launch pad about ten days before launch. NASA missions are launching either from Cape Canaveral Air Force Station, John F. Kennedy Space Center or the Vandenberg Air Force Base, Calif. On the launch pad, the spacecraft-upper stage stack is hoisted atop the launcher. Then a brief functional test is performed to eventually verify the spacecraft state of health, followed by a final week of launch vehicle and spacecraft integrated testing. All those operations aim at performing the final assembly of spacecraft and encapsulate it, before it's taken to the launch pad. While processing requirements differ depending on the spacecraft and mission, they usually include final assembly and testing, integration with a third stage or adapter, propellant loading and spin balancing. Such tasks typically begin about three months before the scheduled launch

What About the Launcher?

The operations are depending upon on the launcher brand, and, inside the brand, to the launcher type. Two main brand currently used by NASA are Boeing and Lockheed Martin. NASA's Launch Services Program (LSP), generally, based at Kennedy Space Center in Florida, specializes in the management of missions flying on expendable rockets, like, for example, purchasing the launch vehicles for spacecraft, matching rockets to spacecraft based on payload, or helping the launching corporate to pressurize tanks, ammonia servicing, and load of hypergolic fuels. The LSP also features a Flight Analysis Division using computer models from liftoff to orbit insertion. LSP's Communications and Telemetry Group also is providing communications, telemetry, data, video and voice recording during key processing milestones and throughout a flight. On launch day, LSP's role shifts from advising to monitoring, following along with the countdown and watching to see how the mission progresses and help with the consoles of the launch team

Boeing Delta

Lockheed Martin

Boeing Delta

In the case of a Boeing Delta II Heavy launcher (a three-stage launcher with nine solid boosters attached at the first stage), first stage is set up at the Vertical Integration Facility (VIF), a gantry-like structure located at the launch pad, as nine solid boosters are installed by set of three one week later. The second stage is mated atop the first stage a further week later. Once the launcher configured, electrical checks are performed four days after as the first and second stages steering systems are checked two days after still. At this stage -about two weeks before launch- a countdown test with the first stage loaded with liquid oxygen may be performed. About the same date a Simulated Flight Test (SFT, or "SimFlight") occurs. It is a flight test with a plus count of the electrical and mechanical systems of the launcher which are to be triggered during the first phase of the flight, between liftoff and spacecraft separation. One day after a first stage leak check is performed. Liquid oxygen (LOX) is loaded and the check is used too to exercise the first stage propulsion team as this same procedure will be used on launch day. Three days later first stage fuel system is qualified by the loading of the RP-1 propellant (RP-1 is a highly refined kerosene fuel) as one day later the second stage is completely loaded with the remaining of hypergolic propellants. There comes the mating of the mission, about 12 days before launch. The upper stage-spacecraft stack is brought to the VIF and it's hoisted atop the launcher. Tests are further performed: the Flight Program Verification, along with an integrated test of the launcher and the spacecraft. First weather data are gathered and a chance percentage of not meeting the launch weather criteria is issued. About three days after the spacecraft arrival, the two halves of the fairing are closed around the craft, with a securing completed on next day. A Flight Readiness Review (FRR) occurs just the day after as checks of the launcher steering system and of the Range Safety beacon are performed about two days before launch. The day before launch, about T-10:00, the VIF is moved away. The gantry was surrounding the rocket until then. Just a simple launch tower is left which is providing the launcher with its last connections Earth, like fuel or communications. In the case of the Delta II launcher, the countdown leading to launch is beginning 2½ hours before launch. The fueling of the first stage with the RP-1 kerosene begins. As far as it is concerned, the launch team is assembling at the launch control center about 3 to 4 hours before launch. The spacecraft/launch vehicle integration and launch countdown management are the responsibility of the Launch Services Program office

Lockheed Martin

In case of an Atlas V launcher, the launcher is transported to the Atlas Spaceflight Operations Center, as the assembly makes use of a Vertical Integration Facility (VIF), a gantry-like, moveable structure located at the launch pad. It's there that the launcher is assembled. About one month later the Centaur upper stage is brought to the VIF and it's mated atop the booster first stage. About one month before launch, a "wet dress rehearsal" is performed with a roll-back of the VIF. The vehicle there is fully fueled with RP-1, liquid hydrogen and liquid oxygen, as the team performs a simulated countdown. The VIF is rolled back to the launcher as final launch preparations are performed, of them the mating of the spacecraft atop the launcher. The spacecraft then endures a functional test, followed by a final week of launch vehicle and spacecraft integrated testing