Mission Extension Vehicles succeed as Northrop Grumman works on future servicing/debris clean-up craft

With the successful docking of Mission Extension Vehicle 2, or MEV-2, to the Intelsat 10-02… The post Mission Extension Vehicles succeed as Northrop Grumman works on future servicing/debris clean-up craft appeared first on NASASpaceFlight.com.

Mission Extension Vehicles succeed as Northrop Grumman works on future servicing/debris clean-up craft

With the successful docking of Mission Extension Vehicle 2, or MEV-2, to the Intelsat 10-02 satellite last month, Northrop Grumman not only repeated the task of successfully attaching one of their MEV spacecraft to a functioning satellite but also successfully proved the ability to grab a still-transmitting telecommunications satellite without disrupting service.

The success of both MEV-1 and -2 has led to an increasing interest in the use of those crafts after their current five-year missions with their present satellites are complete.  Meanwhile, Northrop Grumman has already begun work on the next generations of remote, on-orbit servicing and debris clean-up vehicles.

MEV-2 builds on MEV-1’s success

Launched in October 2019, MEV-1 rendezvoused with its target satellite, Intelsat 901, on 25 February 2020, successfully performing an automated rendezvous and docking in an area of Earth orbit known as the GEO graveyard.

The GEO graveyard is located approximately 300 kilometers above Geostationary orbit, which itself resides at 35,786 km above Earth sea level. 

The first-ever docking in this type of Earth orbit, MEV-1 successfully demonstrated the ability to grab a still functioning but not transmitting or operational-in-that-regard satellite and provide mission extension propulsion and attitude control services.

MEV-1 successfully maneuvered Intelsat 901 back down into the operational GEO belt, allowing it to continue to use its still operational telecommunications services even though its onboard propulsion system was running out of fuel to keep the satellite stable in orbit.

Building on the success of MEV-1, MEV-2 successfully launched in August 2020 on an Ariane 5 ride-share mission into Geostationary transfer orbit.  It then spent the months after launch slowly raising its orbit up to GEO altitude inside GEO’s operational area assigned to its target satellite – Intelsat 10-02.

Therein is the first major difference between the two missions.  MEV-2 was not grabbing a non-operational but still functioning satellite; it was instead given the obligation of docking to a still-transmitting telecommunications satellite in Geostationary orbit.

In this case, going directly to the target satellite while it was still operational in some ways simplified the operations of getting MEV-2 to the correct point in space where it was ready to dock to Intelsat 10-02.

According to Joe Anderson, Director, Mission Extension Vehicle Services, Northrop Grumman, in an interview with NASASpaceflight, “Docking on MEV-1 in the graveyard orbit, we had to use a lot of special operations to avoid [Radio Frequency] interference with other operating satellites in GEO as we were drifting past them.”

Intelsat 10-02 seen from MEV-2 during the latter’s hold during approach at the 15-meter Waypoint ahead of docking on 12 April 2021. (Credit: Northrop Grumman)

“MEV-2 was a little bit simpler for us because we didn’t have that; we weren’t drifting past other satellites.”

Something from MEV-1 that was not originally planned for inclusion on MEV-2’s mission but proved so useful with MEV-1 that Northrop Grumman decided to make it a normal procedure was a calibration — or practice — approach prior to the actual docking.

“On MEV-1, we had incorporated something we called a calibration approach.  Because it was the first time, we wanted to do a practice approach to the client and make sure all our sensors were tuned up properly and that all the systems on both the client’s satellite and our satellite behaved properly as we got close,” said Anderson.  

“We found, actually, that that was a really good idea.  Originally, we didn’t intend to continue that on our subsequent dockings.  But based on what we learned there, we decided that that’s something we definitely wanted to incorporate into our future missions as well.”

Another key change with MEV-2, and a lesson learned from MEV-1, was the addition of a Waypoint, or location along the approach vector where the MEV stops to ensure it is properly aligned with its docking target on the client satellite.

For MEV-1, three Waypoints were used, one at 80 meters distance, one at 15 meters, and the final at 1 meter, at which point the docking sequence was carried out.

“What we found from that,” explained Anderson, “is that it would improve our performance and our confidence in our alignment for the docking if we were to add another waypoint about 3 meters behind the client.”

The new Waypoint was employed on MEV-2’s approach to Intelsat 10-02 and allowed for better control of the actual docking timing given the satellite would still be transmitting to customers on the ground.  The new Waypoint also allowed better confirmation of alignment with the liquid apogee engine on the back of Intelsat 10-02, which was MEV-2’s docking target.

“Intelsat wanted to establish a service window for their customers.  Their customers knew when they might expect a disturbance in their traffic,” noted Anderson.

However, that never happened.

MEV-2 Launch Coverage
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  • “[Adding that Waypoint], that was a good decision.  It really paid off for us on MEV-2, as when we did dock, we had zero transients.  We had no customer outages.  None of Intelsat’s customers experienced an outage when we docked.”

    Docking was conducted in the same manner used for MEV-1, with a docking probe on MEV-2 extended into the liquid apogee engine on Intelsat 10-02.  Once the docking probe passed the smallest part of the nozzle opening, known as the throat, the probe expanded and, like a wall anchor, provided a secure way to slowly pull Intelsat 10-02 down onto the docking clamps of MEV-2, which themselves attached to Intelsat 10-02’s launch adapter ring.

    The method for docking an MEV with a satellite that was never designed to be docked to or serviced in space is a careful part of the overall Mission Extension Vehicle design. 

    “The key there is really finding those features that are present on a large number of GEO satellites that we could attach to because we’re docking to satellites that were not designed to be docked with or serviced,” noted Anderson.  “There are two key factors that are present at about 80% of all of the satellites in GEO.  That is a liquid apogee engine and a launch adapter ring.”

    The launch adapter ring is no longer needed once the satellite separates from the rocket’s upper stage that launched it. The liquid apogee engine is only used for the initial orbit-raising maneuvers to begin the process of getting the satellite into a proper geostationary orbit after launch. 

    Intelsat 10-02, seen from MEV-2 while the latter was approximately 80 meters behind the satellite on 12 April 2021. (Credit: Northrop Grumman)

    Additionally, the MEVs have to be able to dock to satellites using different buses.  These different buses have different properties that affect automated rendezvous and docking operations, such as reflectivity, orientation of solar panels, and placement of attitude control thrusters. 

    In fact, even though MEV-1 and MEV-2 both docked with Intelsat satellites, Intelsat 901 and 10-02 use completely different buses, which had to be accounted for when MEV-2 approached its target. 

    As Anderson related, “The client satellites for MEV-1 and MEV-2 are two different satellite buses.  One was made by Space Systems/Loral at the time, Maxar now, and the other by Airbus.  Those satellites each have their own particular features.  They look different, they have different reflective properties, they have different ways that they do their attitude control, and so you have to be very careful about accounting for all of those as you do your rendezvous approach and docking.”

    Success and future

    The success of the MEV program so far has certainly been seen throughout industry, with interest growing from potential clients.

    “After MEV-1, we received a lot of calls.  ‘Can I get that MEV next?’  ‘Can I get it now?’  ‘If we have a problem, is there any way I could use it?’  ‘MEV-2 is coming, can I get MEV-2?’  We got a lot of interest like that.”

    “I’ve been saying for quite some time that this market is a ‘build it and they will come’ type of market.  We’ve seen good evidence of that since I started working on this in 2012 and visiting customers.”

    In particular, Anderson noted interest within the community as far back as 2012; however, a major hesitation from customers was due to their need for such services immediately while not having a way to adequately predict what their needs would be three, four, or five years later. 

    Anderson found that as the years passed, potential customers would continue to say they required the service right then… but those specific needs changed from year to year.

    “That was the first evidence of: if we build it, if we are there in orbit, those customers will be there,” said Anderson.  “There is just this latent demand for this type of service.”

    But in all of those yearly and regular conversations where Anderson sussed out what the changing needs of customers were, a pattern clearly emerged.  There was a large need for different types of robotic, automated servicing missions for perfectly fine and still operational satellites that were simply running out of fuel to continue to be able to point in the correct direction for service as well as to maintain the orbits needed for those operations.

    In part, this has led to the development of not just the next generation beyond the MEVs but the next generation beyond the next generation, so to speak, of automated, geostationary orbiting servicing fleets.

    “First, we have our next generation system that we’re already constructing.  It’s called our Mission Robotic Vehicle and that’s done in a partnership with DARPA, where DARPA is providing the robotics system.”

    Basically a mini-MEV, these Mission Robotic Vehicles will be able to move from satellite to satellite in Geostationary orbit installing propulsion augmentation systems called mission pods, to satellites like Intelsat 901 and 10-02 that are still functioning but simply running out of propellant for attitude and/or orbital control. 

    The mission pods would provide six years of mission extension service in the form of attitude control.

    Artist’s depiction of a Mission Robotic Vehicle holding a mission pod. (Credit: Northrop Grumman)

    After attaching the mission pods, the Mission Robotic Vehicle (MRV) would undock and move off on another mission.  In addition to attaching mission extension pods, the MVRs would be able to grab satellites and move them into different orbits as well as assist with debris clean-up activities in GEO.

    “We are doing studies into the feasibility of using that robotic vehicle to grapple debris in the GEO orbits,” noted Anderson.  “There is some debris there.  It’s not a huge problem in GEO, but there are some cases where customers would be very interested in having a piece of debris removed.  We are looking at and evaluating the feasibility of doing those types of missions out in the GEO belt.”

    This opens the possibility that the technology employed on the MRVs could be used for other debris cleanup operations, specifically the more cluttered low Earth orbit environment.

    “All of this technology could be applied to those types of debris removal problems,” said Anderson.  “Now the issue that we see with it right now is there is no customer base.  There is no one right now that is incentivized to pay for those types of services.”

    A mission pod attached to a client satellite. (Credit: Northrop Grumman)

    But even beyond that, the third generation of robotic servicing vehicles are already in the planning stages, as well as how they will integrate with future satellites launched towards geostationary orbit. 

    “We’re already starting our generation three, a third generation of GEO servicing for refueling of prepared satellites,” related Anderson.

    “Our approach is to start doing refueling with satellites that are prepared for refueling.  We’re developing refueling interfaces that we would like to make an open industry standard.  Then our vision here is that by 2025, every new satellite that is launched is prepared for servicing in some way.”

    This third generation of vehicle would not just be able to perform refueling operations but also robotic servicing as well using robotic arm technology to repair elements on the exterior, or even interior, of satellites — including an ability to remove and replace solar arrays.

    “Designing solar arrays so they can be taken off or put back on or add additional solar arrays to it… absolutely, that’s on the roadmap,” enthused Anderson.  “That really gets to the next step of our roadmap, actually.  Beyond satellites prepared for servicing is in-space manufacturing, in-space assembly of spacecraft.”

    “That’s something we see coming.  There’ll be a lot of development and incremental capabilities of that over this decade, but we think it really starts to become a capability that we can utilize in the 2030s and beyond.”

    (Lead image: Artist’s impression of an MEV docked to a client vehicle in GEO. Credit: Northrop Grumman)

    The post Mission Extension Vehicles succeed as Northrop Grumman works on future servicing/debris clean-up craft appeared first on NASASpaceFlight.com.

    Source : NASA More   

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    NASA EGS, Jacobs preparing SLS Core Stage for Artemis 1 stacking

    The Core Stage of NASA’s first Space Launch System (SLS) vehicle arrived at the Kennedy… The post NASA EGS, Jacobs preparing SLS Core Stage for Artemis 1 stacking appeared first on NASASpaceFlight.com.

    NASA EGS, Jacobs preparing SLS Core Stage for Artemis 1 stacking

    The Core Stage of NASA’s first Space Launch System (SLS) vehicle arrived at the Kennedy Space Center (KSC) and was moved into the Vehicle Assembly Building (VAB) on April 29. The stage is now in the hands of KSC’s Exploration Ground System (EGS) program and prime test operations and support contractor (TOSC) Jacobs.

    The long-awaited milestone allows EGS and Jacobs to work towards putting the whole Orion/SLS vehicle together and beginning months of testing to get it ready for the launch of Artemis 1. The stage is now in the low bay of the VAB, where some “traveled” work from the recently-completed Green Run design verification campaign will be performed in parallel with preparations for stacking with the new launch vehicle’s Solid Rocket Boosters (SRB), which are already in place on the Mobile Launcher in VAB High Bay 3.

    Critical path to mate

    Two major milestones were recently passed in April. First, Core Stage prime contractor Boeing completed the Green Run design verification campaign on the first flight article, Core Stage-1, at the Stennis Space Center in Mississippi. The stage was delivered to KSC on April 27 and is now sitting in the VAB.

    Just before arrival, the SLS Core Stage team completed the Element Acceptance Review (EAR) for Core Stage-1 on April 26. The review board covered current status and documentation products, and at the conclusion of the review, the Artemis 1 flight article was officially transferred from Boeing to EGS for launch processing.

    The next major milestone is to get the stage mated to the SLS Boosters, which are assembled on Mobile Launcher-1 in the High Bay 3 integration cell of the VAB. For now, the stage is still the primary critical path for the schedule of work to get ready for the Artemis 1 lunar orbit mission.

    Mating the Core Stage to the Boosters is the next big, highly visible milestone, but moving the stage into launch position also opens up major job paths that EGS and Jacobs can then work on simultaneously.

    “I think for us it really comes down to what are the critical path priorities,” Andrew Shroble, Integrated Operations Flow Manager for Jacobs, said. “There’s a lot of parallel work that’s going to be happening once we stack and get the Core Stage mated to the Boosters.”

    “There’s a huge goal to get the whole vehicle stacked, there’s another huge goal to get connectivity and be able to power up as soon as you can to troubleshoot and get through any challenges we’ll have there, and then you have a lot of work that has to happen to get ready for the tests down the line like the Integrated Modal Test (IMT).”

    “If we run into an obstacle or we have a non-conformance issue, then we move onto the next priority, so you’re keeping all these critical paths moving forward at all times. If you run into a kink, you move onto the next.”

    Credit: NASA/Kim Shiflett.

    (Photo Caption: Core Stage-1 is set down on “skid beams” in the VAB on April 29 after offload from the Pegasus Barge. Engineers will install ordnance and make Thermal Protection System (TPS) repairs before the vehicle is repositioned in the VAB for lift operations to mate it with the SLS Boosters.)

    The stage is still resting in its Multi-Purpose Transportation System (MPTS) carrier, where the remainder of the work while it is horizontal will be done. “When we roll the Core Stage into the low bay, we’ll set it down onto these skid beams which basically distribute the load [across the] floor in the low bay,” Shroble said on April 29 just before the stage was rolled into the VAB.

    “The primary objective in the transfer aisle in the horizontal position is to get those areas that are inaccessible once we go vertical in High Bay 3.”

    The stacking, high-bay cells in the VAB are positioned on the east and west ends of the building, with a transfer aisle that runs north-south in between them. The low-bay area extends out from the high bay area on the south side of the building.

    Before it can be rolled from the low-bay to the northern part of the transfer aisle in between the high bays and hooked up to cranes for the lift up into High Bay 3 for stacking, there are a few jobs that can best be performed on the stage in its current configuration. The first task for EGS and Jacobs was to do receiving inspections of the stage.

    “We’ll go right into receiving inspections,” Shroble said. “As part of the NASA handover, to our contract [terms], we have to do full external inspections for any damage and non-conformances that would need to be addressed.”

    The major job originally planned while the stage was horizontal in the VAB Transfer Aisle was installation of the components of the Flight Termination System (FTS). For its first launches, SLS will use the traditional FTS, which would be manually activated by Cape Canaveral Range Safety to terminate an off-nominal launch.

    Following the receiving inspections, EGS and Jacobs will begin installing the Core Stage parts of the FTS. “They’re going to install the linear-shaped charges, the S&As (Safe and Arm Devices), the CRDs (Command Receiver/Decoders) as well,” Nathalie Quintero, Boeing SLS Launch Operations Aerospace and Systems Engineer, said. “That’s all part of the FTS that’s going to be installed here.”

    The FTS assemblies will be installed inside the systems tunnel of the Core Stage, which runs almost the entire length of the element along its exterior. Cover plates will be removed to attach the components to the cable trays inside.

    Credit: NASA/Glenn Benson & Cory Huston.

    (Photo Caption: The -Z side of the Artemis 1 Core Stage is highlighted as self-propelled motorized transporters (SPMT) roll the stage and its carrier into the VAB on April 29. The lighting in the image highlights the long systems tunnel that runs almost the length of the stage and the different cover plates currently installed. The plates with a more glossy appearance are non-flight covers installed for the recently completed Green Run test campaign; all the plates will be removed to install FTS components inside, and only flight covers coated with foam will later be reinstalled.)

    The work was planned for this point in the processing flow because there is better access to the tunnel and the work area now while the stage is horizontal. “The nominal planning was to go install FTS ordnance into the systems tunnel,” Shroble explained.

    Installing the components would be more difficult to do once the stage is vertical and encircled with several levels of platforms. “The linear shaped charges and the FCDC (Flexible Confined Detonating Cord) lines, [it’s difficult] to be able to take a ten or twelve foot linear-shaped charge and walk that up and be able to secure that into the systems tunnel,” Shroble said.

    “So once we get through receiving inspections, we’ll gain access to the systems tunnel. We’re going to pull all the tunnel covers off, expose the systems tunnel, [and] we’ll have the ordnance delivered and pre-staged.”

    “Then that team will come in, install the LSCs, install the FCDC, and then final securing, make sure that connectivity is good, and then they’ll [re]install the tunnel covers,” he added. Once the FTS work is done, that prerequisite to move into stacking preparations would be complete.

    Recent schedule forecasts had projected a couple of weeks for the FTS work, but more post-Green Run refurbishment work on the stage was brought from the Green Run at the Stennis Space Center to Kennedy. Some of that “traveled” work needs to be done before stacking the stage and could take another couple of weeks to complete.

    With the additional traveled work from Stennis, the current forecast for mating the Core Stage to the Boosters is the end of May, beginning of June.

    Extra traveled TPS work

    Some of the refurbishment of the Core Stage thermal protection system (TPS) was moved to the KSC task list while it is still horizontal. In addition, to optimize the remainder of the schedule to Artemis 1, post-Green Run refurbishment work that didn’t need to be done at Stennis was deferred until after arrival at KSC.

    This allowed the stage to be removed from the B-2 Test Stand at Stennis, transported to Florida, and moved indoors inside the VAB. Similar to the work deferred from Stennis, any refurbishment work that doesn’t need to be done while the stage is horizontal will be deferred to later in the launch processing flow; however, there are some TPS inspections and repairs that need to be done now.

    Credit: Philip Sloss for NSF.

    (Photo Caption: Core Stage-1 is rolled off the Pegasus barge at KSC on April 29. In the top middle of the images are two dark areas around the intertank to LH2 tank flange where the spray-on foam insulation (SOFI) closeouts need to be repaired. In addition, the plan is to repair areas of the Core Stage TPS while the stage is in its current horizontal orientation, especially areas that would be inaccessible after it is stacked vertically with the SLS Boosters.)

    “We’ve got a laundry list of things to do and it’s being split up between the Boeing team and the Jacobs team on how we’re going to handle it and try to smartly put the resources out there in the most efficient way possible,” Michael Alldredge, NASA SLS TPS Subsystem Manager, said. “The work is being broken down into access constraints.”

    There are areas around the outside of the stage that are easier to access right now than they will be after it is mated to the two boosters. In particular, after the boosters are attached, they will physically restrict access to external areas on the sides of the Core Stage.

    The boosters will block the 90 and 270 degree locations around the 360-degree circumference of the stage, so any repair locations that would be made hard or harder to reach would be candidates to tackle now. “Once you stack [it is difficult] getting to the 90 and the 270 side because of the Boosters, so the work is being prioritized such that we do the things that we have to do in the Transfer Aisle and then everything else I believe will go in [HB-3],” Alldredge said.

    “We have some repairs to do like on the LH2-Intertank flange,” he noted. “So we’re going to have to dress up and reinsulate the portions of that where we can get to it from the sides.”

    The flanges are where the five major structural elements of the Core Stage are bolted together during assembly. Then, a specific formulation of spray-on foam insulation (SOFI) is manually applied to cover the area to keep as much ambient heat from the outside away from the cryogenic propellants in the two tanks.

    Some cracks were expected to develop in some areas of the foam during Green Run propellant loading and unloading at Stennis, especially during the first full tanking cycle, which occurred on December 20 during the second Wet Dress Rehearsal. “We had the full duration Wet Dress and then we cold-soaked for two and a half, three hours, which is a long time to sit,” Alldredge said.

    Credit: NASA.

    (Photo Caption: A graphic showing the SLS vehicle configuration with the different points around the circumference of the Core Stage. The Boosters attach at the 90 and 270 degree locations; TPS repair work in those areas is being prioritized since they will be inaccessible after the Boosters and Core are mated.)

    Alldredge noted that the flange where the bottom of the intertank bolts to the top of the LH2 tank is where most of the damage was seen. “We did see a number of cracks that did show up there, some of which didn’t get any worse as we got into Hot-Fire #1 and then Hot-Fire #2, and some of which did get a little bit worse,” he said.

    “You see a lot of dynamic energy right there in and around that flange, and so we did pick up a good bit of cracks there, which is not uncommon. We expected that to be a potential, and it showed itself.”

    The more visible TPS damage seen during the two static test-firings was to the bottom of the stage on its base heatshield, but that traveled work can be scheduled for later in the processing flow in parallel with the critical path processing of the assembled SLS vehicle. “We should have very good access to the base heat shield after the Core Stage is vertical and integrated with the boosters in HB-3,” Alldredge noted.

    “Overhead access will make operations less risky compared to operations in-and-around the main engines with the vehicle in the horizontal orientation.”

    Delivery to KSC follows a month of post-Green Run engine refurbishment.

    The SLS Core Stage was the final major Artemis 1 component to arrive at KSC, which will enable EGS and Jacobs to complete launch preparations. Artemis 1 will be the first joint mission of all three of the Exploration Systems Development division programs, and in addition to launching and flying together for the first time, most of the elements will be making their maiden voyage.

    The Core Stage Green Run Hot-Fire that was completed on March 18 at the Stennis Space Center was the final major standalone development test. The stage departed the test facility on April 22 in the agency’s Pegasus barge following a month of refurbishment. After both test-firings at Stennis, the four RS-25 engines needed to be refurbished immediately afterward. There was more work to do after the full-duration firing on the second attempt.

    “[The] first one took 19 days to say we were done and that we were ready for cryos,” Bill Muddle, Lead RS-25 Field Integration Engineer for Aerojet Rocketdyne, said. “From an engine perspective [it took] 19 days to turn around, 29 for the second one.”

    “But the 29 [days] was from when we shutdown to when we were ready to transport, so we had covers and closures [to install], closeout inspections, other things that we had to go do, so it added a little more time on there. All the shipping configuration checks, too.”

    Credit: NASA/Kim Shiflett.

    (Photo Caption: The four Aerojet Rocketdyne RS-25 adaptation engines lead the way as Core Stage-1 is backed out of the Pegasus Barge at KSC on April 29. All four engines are modified Space Shuttle Main Engines (SSME) that served the Shuttle Program as far back as the 1990s; the top two engines as seen in this image helped power the final Shuttle launch almost ten years ago.)

    In the case of the turnaround after the abbreviated hot-fire test in January, the same engine drying had to be performed, but the refurbishment period was shorter because the engines were going to be fired again in the same place and because of the shorter firing time. “We had looked at the requirements in what we call a short-duration hot-fire,” Muddle said.

    “We went through all those requirements, and we actually pared it down a little bit.  We still pretty much looked at everything we looked at on the second hot-fire, but the second hot-fire we looked at it in more detail.”

    Some nozzle tube repairs are typically needed after the engines are fired for full-duration, and there wasn’t as much work to do after the abbreviated first firing. “On the first one we had to fix one engine, on the second one we had to fix all four,” Muddle noted.

    The four engines in the Core Stage are returning to KSC for the first time in almost a decade after being stored at Stennis Space Center for several years. During their Space Shuttle Program service, the engines were refurbished between flights at KSC; Muddle started working on Space Shuttle Main Engines (SSME) for Rocketdyne in 1988 and moved to Florida the next year. “I call them my children,” he said. “So my children are coming home.”

    Now that the flight hardware is in the hands of EGS and Jacobs, Aerojet Rocketdyne and Muddle will be in an oversight role for Artemis 1. “EGS is going to take it over, but Aerojet Rocketdyne will come in, there is some transportation reconfiguration that we have to go do on the engines to get into flight [configuration], so that’s about the only work that Aerojet Rocketdyne has [left] to do.”

    Next step: lift preps

    Once the work in the low-bay transfer aisle is completed, the self-propelled motorized transporters (SPMT) will again pick up the MPTS carrier with the Core Stage on board and roll them into the north transfer aisle between the VAB’s high bays, where the stage will be prepared for the lift “up and over” into High Bay 3 for mating to the Boosters.

    “[We’ll] get into preps for lift, dual-crane operations, going through the spider integration, connecting the aft lifting equipment with the 175-ton crane on the aft end and then basically we’ll do a horizontal lift, remove the GSE (Ground Support Equipment), do a breakover, [and then] we have some leveling to do before we lift into the high bay,” Shroble said.

    The spider, or lift spider, is an identical lifting fixture unit to the one used at Stennis for the whole Green Run campaign. The unit at Stennis was disconnected from the Core Stage before it was rolled onto the barge and after it had been rotated or “broken over” from vertical to horizontal.

    The second unit was delivered to KSC when the Core Stage Pathfinder stopped through in 2019 for shipping and handling practice, and will again be used to take the Core Stage back to a vertical orientation for attachment to the SLS Boosters. The massive spider is too heavy to leave hanging, cantilevered off the front end of the stage for very long, so the load will be shared between different ground support equipment.

    The first piece is the Transportation Interface Fixture (TIF) that will be used to hold the 45,000-pound, yellow-painted spider while it is moved into place and bolted to the top end of the stage. “The ability for the stage to be able to handle that load without any potential damage to the hardware is why they implemented this fixture,” Shroble said.

    “Right now we have the spider sitting in the transfer aisle, so we’re going to connect that to a crane, lift it up, break it over into a vertical position and actually attach it to the TIF. We’ll then disconnect the crane so now the TIF and spider are integrated [and] they’re ready to then be relocated where we can then install the spider to the Core Stage.”

    “Once we install it to the Core Stage [and] they get a set number of pins in, then they actually connect the overhead crane. So there’s a switchover, [the crane will] basically take over the load before fully disconnecting the TIF, and now the full load is actually somewhat distributed into the ground support equipment.”

    In addition to one of the overhead cranes taking up some of the spider’s weight, Shroble said the SPMTs will also be used for support underneath. “What they’ll do is they’ll take the SPMTs and assume some of the load, so it’s kind of like a three-point lift in a way where you’ve got the TIF, you’ve got the overhead crane, and you’ve got the SPMTs supporting to kind of try to lessen the load on the hardware,” he explained.

    The lift operations will be very similar to the practice with the Pathfinder in 2019. One of the two 325-ton cranes will be attached to the spider on the front of the Core Stage, and the 175-ton crane will be attached to lift points on the engine section structure.

    “The 175-ton crane is our transfer aisle crane that runs north and south, that’s going to be used for the aft, and then the 325 number two crane goes [west and east] between High Bay 3 and High Bay 4, so that’s our primary crane used for lifting flight hardware and stacking operations,” Shroble added. “So we break over with both of those cranes into a vertical position.”

    “All the load will be assumed by the 325 number two [crane], and they’ll have slack in the transfer aisle 175-ton crane, and then they’ll disconnect that. And then after they level [the Core Stage] with the master link which is connected to the spider, they then fly it up and be able to lower it down and mate it to the Boosters.”

    Lead image credit: Philip Sloss for NSF.

    The post NASA EGS, Jacobs preparing SLS Core Stage for Artemis 1 stacking appeared first on NASASpaceFlight.com.

    Source : NASA More   

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