NASA EGS Launch Team begins EM-1 countdown simulations

by Philip Sloss

Working through other sequences with ground hardware and support teams

The launch team practices countdown procedures more frequently than just in formal simulations.

“What we are doing between now and July is something called ‘Green Card sims’ and what that means is it’s a little less formal but it is a single system at a time, so just this past week we had our electrical team in the firing room along with our NASA Test Directors, our TOSC test conductor team, our integration console, and myself and we go through and there are problem scenarios that are introduced to the different system engineering teams by the sim team,” Blackwell-Thompson said in the May 2 interview.

“They’re not live data, they’re just problem scenarios that are provided and then we go through and we work through those. Each of our system console teams [is] doing one of those, we do them about every other week or so.”

“That’ll lead into our terminal count first run sim in July and then we have a sim about every month or so; sometimes we have more than one a month but it runs about every month and we kind of alternate between our cryo load and our term count sims.”

All three ESD programs are still in a development phase; additional exercises will be conducted for less hazardous parts of the countdown to run through the choreography of procedures and operations that are still new practice and test experiences.

While the cryo load simulation in April was conducted in Firing Room 2, Firing Room 1 where the launch countdown will take place was busy supporting outfitting work on Mobile Launcher-1 (ML-1) and other KSC facility preparations. “We share it (Firing Room 1) amongst all of us,” Blackwell-Thompson said.

“We have testing operations that are going on for our Multi Element V&V (Verification and Validation) work that’s going on in the VAB (Vehicle Assembly Building). It also supports any MPPF (Multi-Payload Processing Facility) work and so really the reason why we were in Firing Room 2 was that it was the set that was available at the time.”

Once the critical path flight hardware is turned over to EGS for launch preparations, the firing rooms will be staffed to oversee work even before the elements reach the Vehicle Assembly Building, such as spacecraft fueling operations in the MPPF. Currently, those remodeled or renovated facilities are being tested to verify they are ready for those launch preps when the flight hardware is received by EGS.

Credit: NASA.

(Photo Caption: The Mobile Launcher umbilicals and connections for the SLS Block 1 Crew vehicle configuration that will fly on EM-1. These will be connected from the umbilical tower as the vehicle is stacked on the launch platform in the VAB.)

Once ML outfitting in the VAB is complete, it will be moved back to Launch Pad 39B for Multi-Element Verification and Validation (MEV&V) work. A more complete set of integrated pad and launcher systems will be tested.

“We have another set of events that are a part of training, they’re not call simulations but they’re part of what we call ISVVs, which are a series of test events that occur when we have the ML out at the pad for MEVV, for our Multi-Element Verification and Validation,” Blackwell-Thompson said. “As part of that we have what we call ISVVs, which are Integrated System Verification and Validation events and one of those is going through our launch countdown preparations and our launch countdown ops.”

“And by that what I mean is we will go through and demonstrate items that are critical in launch countdown, things like configuring the ML for launch, things like clearing the pad, we’ll go through and do a series of sound suppression water flows while we’re there, there’s a series of events.”

“We do have one that is very specific to our cryo loading ops and to our launch countdown preps and we’ll go through and do some of those physical things out at the pad like clearing the pad and we will have site safety involved in those things and we’ll go through those and we’ll run that just like we would expect to do on launch day,” she added.

Credit: NASA/Michael Miller.

(Photo Caption: A fire extinguishing system (Firex) test of Mobile Launcher-1 (ML-1) while at Pad 39B last September.  Fit checks of ML-1 at the pad and a subset of integrated system tests were performed, but a more exhaustive set of tests are planned for later this year when the fully outfitted ML returns to the pad.)

ML-1 rolled out to Pad 39B late last Summer for a fit check of a few of the facility services. The MEV&V work when it returns will test more of the services that run through connections from the pad to the ML.

“We have something we call ISVV 12, which gives our day of launch demonstration and we go through and configure the firing room, we have the Mobile Launcher at the pad, and we go through and we test out a lot of our tools,” Blackwell-Thompson noted. “We also have our simulated data coming from the vehicle and ground systems and we go through and look at our day of launch configuration. That’s one test that we do.”

“Also in preparation for some of our other V&V testing, we’ll flow cryos up to the Mobile Launcher and then kind of turn them around. As part of that we also do a simulation where we’ll go through and look at our software and our loading one more time against the [computer emulator] model before we actually do that what we call cold flow with the Mobile Launcher and with the cross-country lines and the storage area spheres.”

“So I guess if I were summing it up, we have a suite of simulations that we do with the team that involve pretty much software,” she explained. “Our software will run in the firing room on launch day, we run that against the set of simulators and emulators for both the ground systems and the flight [systems], that’s kind of the first step.”

“Then we also have our ISVV testing where we’ll actually go through with some of our ground systems hardware at the pad and demonstrate this capability with the hardware and so when you take the two of those together, and again we’re doing the software piece and the reporting protocols and the simulations repetitively. I think when you take all of the pieces together it puts us in a really good posture for being ready for the flight hardware, the testing of the flight hardware, and then ultimately the wet dress and launch.”

Countdown outline mostly unchanged

The outlines of the two-day long EM-1 launch countdown were worked out some time ago. “I think we set the framework for launch countdown pretty solid so that we have the ability to kind of flex and so really there haven’t been any significant changes to our launch countdown planning since we last talked in terms of how the countdown played out, the number of hold points, that sort of thing,” Blackwell-Thompson noted. “It still sits at just under two days long at forty-five (hours), forty (minutes) is the L-time, the true time on the clock for that.”

Two built-in holds are planned; similar to the “pre-tanking” hold at T-6 hours, 40 minutes, the thirty-minute long hold at T-10 minutes is just prior to starting the automatic sequence part of the terminal countdown.

“Our final planned hold point is T-10 minutes,” she said. “That’s where we will make sure our team is ready to proceed into terminal count and that is where the sequencer will pick up and once we get into that terminal portion of count we do have a limited amount of hold time, it’s on the order of minutes and so once we get into that terminal portion of count we have a few minutes that we can hold there in the event we have an issue, very similar to what we had back in Shuttle.”

The ground-side automation is new software, but retains the Ground Launch Sequencer (GLS) name from Shuttle; it will run the sequence from T-10 minutes down to the last half-minute of the countdown. GLS will automatically run through the operations to configure the flight and ground systems for engine ignition and liftoff, monitoring a large set of parameters to make sure they stay within limits.

As in Shuttle, GLS hands over primary countdown control to the SLS flight computers in the last half-minute where the launch vehicle’s Autonomous Launch Sequencer (ALS) begins monitoring that set of Launch Commit Criteria, starts the final set of equipment, including the Core Stage engines and then the Solid Rocket Boosters, and then begins flying the vehicle towards orbit insertion.

The Launch Control Center will be staffed around the clock for the count. “Once launch countdown starts we are a 24/7 operation and we’ll be staffed for three shifts a day through the launch countdown,” Blackwell-Thompson said.

With much of the flight hardware is still due at the launch site and with a broad amount of first-time work still ahead, the timing of the final shift handover is still to be determined. “In Shuttle, the way that we did it is we would have a team that would come in and you would make that handoff between what we would call the tanking team and the T-0 team right about the time that you get to replenish,” she noted.

“We haven’t decided for EM-1 quite where that point is yet and the reason is that because our first mission is uncrewed, once we get to replenish we only have a couple of hours of work left until we get to T-0. We [have] to figure out where does it make sense to make those shift changes for the EM-1 mission, but I do expect that we will have some shift change that happens in between or as part of our tanking operations to the T-0 portion of count, we’ve just got to figure out where that is.”

Similarly, the length of the pre-tanking hold at T-6 hours, 40 minutes hasn’t been finalized. Blackwell-Thompson noted the preliminary bookkeeping is a 90-minute duration, but she said in an email that “we will adjust the duration once we have completed some of our ground system V&V testing and finish up green run at Stennis.”

Going back forty-years the countdown operation in Shuttle was known as Operations and Maintenance Instruction (OMI) S0007. Moving to digital from paper, the countdown for this vehicle and ground system is known as Work Authorization Document (WAD) 3210. “We’re using electronic WADs and so part of our development and execution tool that we’re using for those WADs has a different numbering system. We refer to it as 3210 and so 3210 is going to be the number of our launch countdown,” Blackwell-Thompson said.

Looking at EM-2

As with assembly, analysis, and preparations for the second integrated EGS launch of Orion and SLS on Exploration Mission-2 (EM-2), Blackwell-Thompson said that countdown planning for the first crewed launch is running in parallel with the EM-1 work. “We’ve absolutely started the planning for launch countdown, we’ve begun looking at the time-frame and how we would go do the crew ingress which would be after we got to replenish,” she said.

“A lot of the countdown up through our replenishment operations looks exactly the same [as EM-1]. What we do see is there is some increase in time from replenish down.”

“We’re very streamlined for EM-1 because without the crew there we just have a limited amount of work to go do,” she added. “We do see that time increase because obviously we have to get the crew in, get them strapped in, configured, comm checks done, all of the crew module configuration done and closed out.

Credit: NASA/Rad Sinyak.

(Photo Caption: The open hatch on the Launch Abort System ogive fairing for the Ascent Abort-2 test vehicle during test preparations in the Launch Abort System Facility in May. On launch day with the flight version of the spacecraft, flight crews will ingress Orion through the ogive hatch and the spacecraft’s side hatch.)

“So that takes some extra time after replenish down to T-0 and we’ll be making accommodation for that but we’ve already laid out that work and we have a good understanding of what that is and we’re already starting to put that planning into place.”

With the additional work timeline between the “stable replenish” point that signifies the vehicle is fueled for launch and the terminal countdown sequence, one of the options for crewed launches like EM-2 is to add a built-in hold in the countdown. “We have two different ways we go accomplish this,” she said. “We can pull the launch countdown back to the left and just add additional time in or we can put in a hold point after we get to replenish as we get ready to send the crews to the pad, which would be very similar to what we had in Shuttle.”

“And that gives you a catch-up point. We also have our final hold prior to terminal count, which I don’t expect any changes there and that also serves as the same thing where we can do a final catch up point and verify that we’re all ready to go, but we absolutely are looking at whether or not it makes sense to put in an additional hold somewhere in between where you finish up your tanking operations and the one at ten minutes.”

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