Today, the Artemis 1 launch vehicle rolls-out of the Vehicle Assembly Building (VAB) at Kennedy Space Center. Not since the roll-out of the Apollo 17 launch vehicle on August 28, 1972 has NASA rolled-out a fully integrated, super heavy-lift, space exploration vehicle. The Artemis 1 roll-out is another step towards making the dream of the Orion spacecraft and the Space Launch System, created by the 2010 NASA Authorization Act, a reality, to build a crew-rated spacecraft and launch vehicle capable of supporting human spaceflight, “…access to cis-lunar space and the regions beyond low-Earth orbit in order to enable the United States to participate in global efforts to access and develop this increasingly strategic region.”1 For the many thousands of NASA civil servants, NASA contractors and their employees, and all of the other people who in some way touched the programs that make up Artemis, today must be as rewarding as it was for those supporting Apollo when Apollo 4 first rolled-out of the VAB on August 26, 1967.
Today’s roll-out started with assembling, or stacking, the Artemis 1 launch vehicle inside Kennedy Space Center’s Vehicle Assembly Building’s High Bay 3. The VAB has four high bays and four low bays. Renovation of High Bay 3 and adjacent High Bay 1 began in 2011 and included removing, “…about 150 miles of Apollo/shuttle-era cabling from high bays 1 and 3 to make room for installation of future state-of- the-art command, communication, and control systems that will be needed by future users to perform vehicle testing and verification prior to rollout to the launch pad,”2 as well as all new work platforms contoured to the Artemis launch vehicle3. Stacking of Artemis 1 began on Saturday, November 21, 2020 with the mounting the aft segments of the two 5-segment solid rocket motors on Mobil Launcher 1.
After stacking of the Space Launch System portion of the Artemis 1 vehicle was completed, on August 13, 2021 NASA began integrated modal testing of the Artemis vehicle. The integrated modal testing involved over 300 sensors mounted on the launch vehicle, mounting a test version of the Orion stage adapter and Orion mass simulator, installing hydraulic shakers in seven locations on the rocket and a small hammer that delivered calibrated taps near key parts of the navigation system to understand the dynamics local to those spots4. Testing was conducted over several days for 10 hours each day during the night hours when the activity level within the VAB was at a minimum. Modal testing is important for any structural system, but especially so for launch vehicles–and bridges–because if any system of a launch vehicle, for example the engines, are vibrating at the same frequency as the natural, or resonant, frequency of the SLS vehicle or Orion spacecraft, it could cause those to shake violently.
For example, Apollo 6 experienced vibrations, what is called pogo effect, to the point that, had a crew been aboard, they could have been injured. The pogo effect experienced on Apollo 6 was serious enough that then-Director of Marshall Spaceflight Center Wernher von Braun said, “…the flight clearly left a lot to be desired. With [this problem], we just cannot go to the Moon.”
According to Dr. John Blevins, SLS chief engineer, the data from the integrated modal test will be fed into the SLS launch vehicle guidance and control flight software and navigation system so it can distinguish the rocket’s natural frequencies from the vibration frequencies experienced during flight and modify the flight to manage the vibrations and reach orbit without depleting fuel because it was reacting to natural vibrations it could ignore. Although integrated modal testing has been completed, the sensors remain on the launch vehicle and, according the SLS Program Manager John Honeycutt, modal testing of the Artemis vehicle continues during roll-out.
Stacking resumed with completion of the integrated modal test, removal of the Orion stage adapter structural test article and Orion mass simulator, and stacking of the Orion stage adapter on October 12, 2021. On October 22, 2021, the Orion spacecraft was stacked on the Artemis 1 vehicle, completing stacking of the Artemis 1 vehicle. On March 14, the Artemis 1 vehicle received its paint job of the NASA worm on both solid rocket motors, and, on March 16, the last work platform was retracted revealing the full Artemis 1 vehicle.
Stacking wasn’t the only Artemis activities happening while the Artemis vehicle was being stacked. According to Mike Sarafin, Artemis Mission Manager, recovery teams have continued training and getting familiar with the hardware, including a recovery test on March 2, which went well. Sarafin mentioned that, unlike Shuttle, once Orion initiates its trans Earth injection burn, or TEI, Orion is on a 4 day coast back to Earth, regardless of changes in the weather. So any planning for adverse weather in the Pacific, near San Clemente Water Landing area where Orion splashes-down, is important. He also mentioned that the Orion spacecraft does have a 1,000 mile range to steer around any poor weather that appears.
According to Artemis Launch Director Charlie Blackwell-Thompson, once roll-out from the VAB starts, two weeks of work begin. First, the Crawler-Transporter 2 (CT-2)5, traveling at a nose-bleeding 0.8 mph, will pull the Mobile Launcher 1 out and then pause outside the VAB. This is to give engineers time to extend and lock into its travel position the Crew Access Arm (CAA), which interfaces with the Orion spacecraft stack, that had been moved closer to the rocket to fit through the VAB door. Once this step is completed, Crawler-Transporter 2 will resume its break-neck pace of 0.8 mph and resume its 11 hour trip to move Mobile Launcher 1 and Artemis 1 vehicle to launch complex 39B and set Mobile Launcher 1 on the pad’s hard-down points. NASA has two crawler-transporters. Crawler-Transporter 2 was assigned to work on Artemis and reconditioned to update the 50 year old vehicle in anticipation of its new heavy load and even tested for heavier loads than planned.
Once Crawler-Transporter 2 has delivered Mobile Launcher 1 to LC-39B, the mobile launcher will be mated to data, power, and purge ground connections. Following that, there will be validation that those services are available and ready to go.
Next up are functional tests of the Artemis 1 vehicle. These include communications, electromagnetic interference (EMI), and electromagnetic compatibility characterization (EMC), among others.
After that, booster service operations begin with the loading of hydrazine, which is used to power auxiliary power units (APU) within each of the Space Launch System solid rocket boosters. Each booster needs the APU power to provide hydraulic power used in gimbaling of the motor’s nozzle.
Then, after the functional tests and booster servicing are completed, the Wet Dress Rehearsal can begin, and will last two days. This involves all of the activities on launch day such as loading the Artemis Core Stage with liquid hydrogen and oxygen.
Once the wet dress rehearsal is completed, for the next 8-9 days the SLS Core Stage is drained of liquid hydrogen and oxygen, everything is safed, and the solid rocket boosters are deserviced.
It will be at this point that a launch date will be set, according to Mike Sarafin.
Many people made today possible. But it would be remiss for there to be no mention of the bipartisan members of Congress, and their staffers, who, against great odds and in spite of strong opposition within the Obama Administration forged the 2010 NASA Authorization Act and then passed it. In particular, the former Chairman of the Senate Space and Science Subcommittee, Senator Bill Nelson, played a key role in bringing the legislation to law.
This effort by Congress culminated in a publicly televised debate in the House of Representative on September 29, 2010, House Speaker Pelosi presiding, over the competing House and Senate versions of the NASA Authorization act that lasted until 11:36 pm when the House passed S. 3729 with 304 votes, or by 72%6. Even with that strong show of support by members of Congress, few expected on September 29, 2010 that Congress would each year actually stand-up to the challenge of fully funding the Orion and SLS programs it created in 2010 and doing so without presidential support because, to be historically accurate, Congress had not done so since Apollo and even then it only did so under great pressure from President Lyndon Johnson. But stand-up Congress did; year-after-year, congressional appropriators provided funding increases in spite of annual efforts during three administrations to decrease funding to the programs that today make up Artemis.
NASA has had a long and difficult path to this day. But Roll-Out is today, and it is a day which not only NASA but all of the other people who made this possible should celebrate. Everyone, from the engineers, technicians, civil servants, contractors, to all of the others, including members of Congress and their staffers past and present, who touched this program, all of them made this day possible. Today begins the peaceful march by NASA and its Artemis Accord partners to return to the Moon after a half-century absence and the laying of the foundation for human exploration of Mars and beyond, one that will serve as a bright shining light of hope for all to see.
- National Aeronautics and Space Administration Authorization Act of 2010, P.L. 111-267, 124 STAT. 2813, 42 USC 18322 ↩︎
- Vehicle Assembly Building, NASA ↩︎
- Vehicle Assembly Building High Bay 3 Work Platforms ↩︎
- Vibration Tests for Moon Rocket Help Ensure Safe Travels on Road to Space ↩︎
- Crawler-Transporters ↩︎
- All Action S. 3729–111th Congress (2009-2010) ↩︎
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