The Orion spacecraft and SLS rocket for NASA’s Artemis 1 mission are assembled, the Mobile Launcher is reconnected to the vehicle, and the processing team at Kennedy Space Center (KSC) is resuming pre-launch testing and checkouts in High Bay 3 of the Vehicle Assembly Building (VAB) ahead of the first rollout to the pad.
The agency’s Exploration Ground Systems (EGS) program and prime launch processing contractor Jacobs started the final stretch of integrated testing and checkout (ITCO) in early November and are aiming to complete the remaining work in the VAB to enable the first trip to the pad around the end of the year.
The upcoming stretch of tests conducted between the launch control center and the VAB at Launch Complex 39 will verify all the connections between the vehicle and ground systems, followed by final functional checks of spacecraft and rocket machinery. After final closeouts, the integrated Artemis 1 vehicle will be rolled to Pad 39B for the first time for its last big pre-launch test, the Wet Dress Rehearsal, currently projected to occur in January.
Integrated testing and check-out (ITCO)
A second, more complicated round of verification testing for the SLS Core Stage and twin Boosters started the week of November 8 after final preparations were completed by the integrated operations team.
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“The Boeing guys are finishing up some traveled work in the engine section to get us into a configuration to now go back into the integrated vehicle testing,” EGS Operations Flow Manager Lili Villareal said in a November 5 interview.
Boeing is the prime contractor for the SLS Core Stage; the first flight article also served as a propulsion test unit for the Core Stage Green Run design verification campaign at Stennis Space Center in Mississippi. The company is finishing up post-Green Run modifications ahead of the vehicle’s first launch, and thermal protection system (TPS) repairs from the full-duration firing in the B-2 Test Stand at Stennis in March.
After a verification test of the Mobile Launcher (ML) umbilical release system and modal testing in late September, EGS, and Jacobs prepped the vehicle for the bulk of the ITCO campaign. Following a set of interface verification tests (IVT) at the end of the summer, this round of the IVT is now being referred to as integration (versus interface) verification testing.
In addition to bringing Orion in for stacking to complete the Artemis 1 vehicle in October, the ML umbilicals had to go through a maintenance cycle of inspections and repairs and then be reconnected. “That [umbilical reconnection] was our most critical path, and we got all the umbilicals mated/attached and ready to go to be able to power up the Core Stage and Boosters,” Villareal said on November 5.
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“We’re still finishing up the ICPS umbilical, that’s the last one, and we should finish that up sometime late next week. But that’s OK because we’re going to be taking our time to do the Booster and Core Stage IVT.” A few days after Orion was mated to the SLS in late October, the two-connection Orion Service Module Umbilical was attached to the spacecraft so it could be powered up for the first time after being stacked on the Mobile Launcher.
“There [were] no issues when we powered up Orion,” Villareal said. “The battery life is [good] and things went well there.”
Individual vehicle components were powered up during the initial interface tests; in the upcoming tests, EGS and Jacobs will be verifying integration and intercommunication between the elements.
“We’ve done some separate IVTs for the Booster, we’ve done separate IVTs for the Core Stage, [and we verified] ‘yes we can talk’ [and] we’ve loaded software,” Ron Constantino, Operations Integration Manager for Jacobs, said while speaking with NASASpaceflight on November 5.
Credit: Philip Sloss for NSF.
(Photo Caption: Partially obscured by platforms and scaffolding, the top of the Artemis 1 vehicle is seen in the VAB on November 5. The umbilical tower of the Mobile Launcher is seen to the left of the vehicle. With the exception of the Orion Launch Abort System and launch fairings, SLS will send the white-colored flight elements seen here on a trajectory to the Moon on Artemis 1.)
“So now we get into these big, integrated vehicle tests [to verify] we have a good operational understanding [that] yes, the [updates] have been made, yes, they are operating correctly, and yes, we are getting the right readings in our control center. You’re trying to tie in these individual systems with our GSE (Ground Support Equipment) systems and saying, yes, we are ready to go.”
“We’re going to do the Boosters to the Core Stage, then we’re going to do Core Stage to ICPS,” Constantino noted. “We’ve already done the Orion one.”
“We’re going to get into PSET (Program Specific Engineering Testing), we’re going to do functional checkouts of every little system out there, to make sure there are no disconnects or any breaks in the systems, whether it’s software or hardware-related. Once we’re completed with that, we get into the big IVT.”
“The big IVT is really going to be our first opportunity to test out the vehicle as one vehicle,” he added. “You’re going to run it through all the ringers, make sure that everything is operating correctly.”
There are different parts of the IVT to conduct before that big IVT, and as those are completed, the PSET engineering tests will begin. Currently, PSET testing of the Boosters and Core Stage for the SLS Program would begin next week (week of November 15) after the part of the verification tests being performed this week.
There will also be engineering tests on the ICPS after the in-space, second stage of the SLS completes its integration verifications. The SLS Program, which makes its home at the Marshall Space Flight Center in Huntsville, Alabama, has a resident office at KSC, which is coordinating support for the upcoming engineering tests on the vehicle in the VAB.
“There’s the various discipline teams that are a part of those PSETs, those individual tests,” Elkin Norena, Manager of the SLS Resident Management Office (RMO)for NASA, said. “I have to coordinate with my team to get the right support for each of those individual tests as they come up on the schedule, either remotely or folks that have to fly down to support them locally.”
“[With] these tests being back to back to back, we have to make sure we’re right on point to support that schedule.”
Over the next month to month and a half, the schedule is filled with vehicle testing and checkouts; although a lot remains to be completed for this first launch campaign and there may be a few surprises to come, the people at KSC are seeing the proverbial light at the end of the tunnel and anticipation is rising.
Credit: NASA/Radislav Sinyak.
(Photo Caption: Wider views of the Artemis 1 stack seen shortly after Orion was lifted on top of SLS in late October. The vehicle will remain surrounded by platforms and scaffolding in VAB High Bay 3 until just before it rolls out to the launch pad for the first time.)
“Every day we see things completing and checkmarks coming off, and just we’re so close so it’s really exciting,” Villareal said.
“There’s definitely a lot of things that we have coming ahead of us, but it’s also very exciting,” Constantino added. “I was an old [International Space Station] manager back in the [Space Shuttle STS] 134, 135 days, and now we’re seeing a vehicle integrated in the VAB and we’re watching people work.”
“If you look across the center, we [Jacobs] have people working every facility in the center, so it’s a time of excitement. I mean, literally, we’re having meetings yesterday about ‘Are we ready at the pad? Are we getting things moving? What’s the next steps for us?’.”
Pre-rollout test sequence
The most complicated ITCO test remaining is an end-to-end communications test that will involve NASA people, programs, centers, facilities, and networks beyond KSC. “The comm end-to-end is really the critical one,” Villareal said.
“And it’s really critical from a scheduling perspective because it really requires so many assets of NASA to be supporting it, and so we have to really align when we’re going to do that because you’re talking about getting a lot of assets [coordinated]. There’s a lot of the other [NASA programs] that are using the hardware that we need to [perform the] test, so you really have to plan way in advance, and you have to hold that schedule.”
Currently, the planning schedule is projecting that test at the beginning of December. Beyond integrated countdown and launch simulations for Artemis 1 that involve all the EGS, Orion, and SLS support teams at other NASA centers, Villareal said the comm end-to-end test brings in downrange and in-space communications systems that will be needed on launch day, such as the Tracking and Data Relay Satellite (TDRS) network.
EGS and Jacobs have more flexibility in scheduling other tests. “We have the ability to move tests [around on the schedule], now that everything is stacked and integrated,” Villareal said. “[We can schedule] the separate vehicle tests differently, but the comm end-to-end test [schedule] is really the one that we want to hold.”
That big communications test is the first in a final sequence of test operations prior to rolling the vehicle and Mobile Launcher out to Pad 39B together for the first time. The next major test in that sequence is a countdown sequence test (CST), where the ground command and control computer system and the Ground Launch Sequencer (GLS) that will control the 10-minute long terminal countdown will run through the countdown with the flight vehicle.
The Artemis 1 launch team and the ground systems for launch have been tested in a series of countdown simulations using software emulators to stand in for the flight hardware and create scenarios for troubleshooting practice. The simulations are continuing in parallel with the hands-on hardware preparations in the VAB, but the countdown sequence test is one of the first opportunities to run a countdown sequence with the computers, software, and flight systems of the all-up Artemis 1 SLS and Orion, albeit in an unfueled configuration.
Following the countdown test, EGS and Jacobs will begin final configurations of the flight termination system (FTS) for launch. Due to operational constraints, the final FTS installations, testing, and checkouts are split into two parts. The first is performed after the countdown test and the second/last performed after the vehicle returns to the VAB from the first pad rollout.
The first part of the FTS tests will be one of the final checkouts that need to be performed before the vehicle is ready for a first rollout to the pad. Getting EGS, Orion, and SLS to the point where they are ready for their first launch together on Artemis 1 has been a long series of “integrate and test” cycles and the fully-integrated vehicle will roll out to Pad 39B for the final one planned.
Credit: NASA.
(Photo Caption: A diagram of all the communication links used during the initial Orion missions with the SLS Block 1 vehicle. An upcoming pre-launch end-to-end communications test will verify that all of the links locally to the Kennedy Space Center area and beyond work. In addition to two-way communications with the in-space TDRS network and receiving data from the Global Positioning System, Orion and SLS will also downlink critical, real-time operational and test data to a downrange tracking station in Bermuda. Pre-launch testing will also verify that Mission Control in Houston can receive the data and uplink commands during the flight.)
Crawler-Transporter 2 will carry the Mobile Launcher with the Artemis 1 vehicle on it out to the launch pad for the first integration of a flight-ready vehicle and ML with the pad systems that will be used for the final launch countdown and fueling. The ML and Pad 39B systems have gone through integrated verification and validation together, and the Orion and SLS vehicles have gone through their standalone testing, but this will be the first time everything is in essentially a launch countdown configuration.
At the pad, a full-vehicle Wet Dress Rehearsal (WDR) is the final pre-launch exam for everything together. The WDR is a full launch countdown that will see countdown preparations fully exercised for the first time, followed by a high-fidelity countdown that will look and feel a lot like launch day.
The EGS and Jacobs ground control systems will load propellant on the SLS Core Stage and ICPS for the first time at KSC during the WDR, with the Ground Launch Sequencer (GLS) following launch day countdown timing, sequences, and launch commit criteria. After the two cryogenic stages are filled with their liquid hydrogen and liquid oxygen propellant and the propulsion systems and engines are thermally conditioned for launch, the launch team will initiate the GLS automated terminal countdown sequence, and the vehicle will be prepared for ignition.
The GLS will command the vehicle to pressurize for flight and isolate it from ground services in the final minutes and seconds before the planned T-0 time. The launch team will twice run through practically the full terminal countdown, also practicing the ability to recycle the vehicle from a last-minute hold back to the point where the team and the systems are ready to make another terminal countdown run at launch.
During the first run of the WDR, the countdown will be stopped just before the hand-off of flight vehicle control from the GLS to the SLS Core Stage flight computers. Vehicle safing will be initiated, and the countdown will be recycled back to T-10 minutes.
After recycling the vehicle and ground systems to be ready to count down again, for the second terminal countdown pass in the WDR, the GLS hand-off will be completed, and the SLS Autonomous Launch Sequence (ALS) will take over control of the vehicle for the rest of the countdown through launch and insertion.
The SLS flight computers running ALS will start the SRB hydraulic power units, make sure that the Core Stage RS-25 engines are ready to start and get ready to issue start commands before cutoff is given in the WDR, which will again initiate the automatic safing sequence from that point within a second or two of engine ignition.
Lead image credit: NASA/Frank Michaux.
