NASA to roll back SLS for repairs

NASA announced late April 16 it will roll back the Space Launch System from the launch pad for various repairs, further delaying the rocket’s long-anticipated first launch. In a statement late April 16, NASA announced it planned to roll back the SLS to the Vehicle Assembly Building (VAB) “due to upgrades required at an off-site supplier of gaseous nitrogen used for the test,” the agency said. Problems with the supply of gaseous nitrogen, used to support activities at the pad, had delayed two previous countdown rehearsals. NASA did not state when the vehicle would go back from Launch Complex 39B, where it rolled out March 17, to the VAB. The agency said it will hold a briefing April 18 about its plans. The agency added it would use the time in the VAB to repair a faulty helium check valve in the SLS’s upper stage and a hydrogen leak detected shortly after starting to load liquid hydrogen into the rocket’s core stage during the April 14 attempt. It was the first time that controllers had reached that stage of the countdown after technical problems halted two previous attempts before liquid hydrogen could start loading. The leak is on the ground side of an umbilical plate on the mobile launcher’s tail service mast, and not on the SLS itself. “The good news is that there’s only a few things in that purge enclosure and there’s a couple of discrete penetrations that could be the culprit,” said Charlie Blackwell-Thompson, Artemis launch director, during an April 15 briefing.

NASA said late April 16 they will roll back the SLS to the VAB in order to fix a gaseous nitrogen issue at the pad and do repairs to the SLS and its mobile platform. Credit: NASA/Joel Kowsky

At that briefing, agency officials expressed some optimism about correcting the problem on the pad. Mike Sarafin, NASA Artemis mission manager, said those potential sources for the leak represented “low-hanging fruit” for fixing the problem and allowing another wet dress rehearsal as soon as April 21.

However, he suggested even then that rolling the SLS back the VAB was an option. “There are some more invasive options that require getting further into the hardware and potentially having to get into some extended troubleshooting,” he said, work he indicated might be best done in the VAB.

Sarafin said engineers also had to consider environmental issues of having the vehicle on the pad for an extended period, such as wind stresses on the towering vehicle. “The longer we stay at the pad, the more we stress the vehicle,” he explained. “Every time the wind blows against it, it creates a bending moment and, over time, that adds up.”

“We haven’t fully outlined all the options right now,” he said at the April 15 briefing. “The one that we’re pursuing with great vigor is the low-hanging fruit option and we’ll let the team come up with some other options.”

Blackwell-Thompson suggested one option would be to do another tanking test once the vehicle returns to the pad for the Artemis 1 launch. “You could certainly look at your schedule risk for launch countdown and make a decision whether or not you wanted to do a tanking prior to a launch countdown,” she said. In that scenario, the rocket would go through a tanking test and practice countdown and, if all went well, “some days later decide to go launch.”

Despite not getting through the countdown test in three attempts to date, and uncertainty about when the hydrogen leak will be fixed, Blackwell-Thompson said she was not particularly concerned. She noted there were five or six tanking tests before the first launch of the shuttle more than four decades ago. “Putting it into context, I would say we’re within family of our experience in the past for first-time ops,” she said.

NASA rings in busy new year in Florida to prepare for Artemis Missions

NASA's Kennedy Space Center in Florida will have a busy year preparing facilities, ground support equipment and space hardware for the launch of Artemis I, the first uncrewed launch of the Space Launch System (SLS) rocket and the Orion spacecraft. In 2020, Exploration Ground Systems (EGS) activities will ramp up as launch hardware arrives and teams put systems in place for Artemis I and II missions. Launch countdown simulations will continue to ramp up in 2020 to train and certify the launch control team for Artemis missions. The types of simulations will build on one another and will walk through the final portions of the launch countdown sequence, called the terminal countdown. Integrated simulations will tie in all NASA centers working the mission to ensure all members of the team are ready to work together, including Mission Control at Johnson Space Center in Houston, and the SLS Engineering Support Center at Marshall Space Flight Center in Alabama. Simulations will begin at the end of January and will occur up through one week before launch, with an average of one training exercise each month. Much of the work in 2020 will be to complete a punch list of detail work inside the Vehicle Assembly Building (VAB). This includes cleaning the platforms and making minor repairs to any platform hardware that will be near flight hardware as the facility prepares for arrival of SLS components and stacking operations. "We are at a very significant point in NASA's Artemis mission," said Mike Bolger, program manager of EGS. "The EGS team has finished mobile launcher testing at the launch pad and will finish testing at the VAB in January. At that point, all of the launch infrastructure will be tested and ready for operations."

Launch Complex 39B
Teams will continue work on a new emergency egress system for Pad 39B where flight or ground crew could board a basket with a braking system at the crew access level of the mobile launcher. The crew would ride the basket down a cable and come to a stop near a bunker to the west of the pad surface, providing quick escape in the unlikely event of an emergency. The design phase began in 2019 and construction will be complete in time to support crewed Artemis missions.

The pad is currently getting a liquid hydrogen upgrade. The project involves the integration of a new 1.4 million gallon, liquid hydrogen (LH2) storage sphere into the existing Launch Complex 39B system. The new LH2 sphere will work with the current LH2 sphere to supply LH2 for Artemis II and beyond. The larger tank will allow NASA to attempt SLS launches on three consecutive days, instead of opportunities two out of three days, in the event of a scrub. The newer technology reduces liquid hydrogen burn-off, allowing more launch attempts before having to refill the larger tank. Construction began in 2019 and will be complete prior to Artemis II.

Orion Underway Recovery Test 8
The integrated recovery team of NASA, EGS, Lockheed Martin and the U.S. Navy, along with additional contractor support, will head out to sea off the coast of California in March to conduct the eighth Underway Recovery Test. Using a Navy ship with a well deck and several small boats, the primary objective is to validate Orion recovery operations for Artemis I - including procedures and timelines, and practicing different scenarios.

Orion Spacecraft
This spring, the Orion spacecraft for Artemis I will return from NASA's unique test facility at Plum Brook Station in Ohio, where it is currently undergoing environmental testing inside the vacuum chamber that simulates the harsh environment of space.

Inside the Neil Armstrong Operations and Checkout (O and C) Building at Kennedy, technicians will install the spacecraft's solar array wings before performing final checkouts. EGS will begin Orion ground processing and stacking activities later in the year.

The team will process and fuel Orion in the Multi-Purpose Processing Facility then transfer it over to the Launch Abort System Facility where engineers will attach the launch abort system. Orion will then roll out to the VAB for inspections before stacking Orion on top of the SLS rocket.

In its early processing stages, the Artemis II crew module milestones inside the O and C include propulsion tank installation, a pressure test and subsystems installations in the spring. The initial power-on of the crew module will occur in early fall. The heat shield that will protect the first crewed mission of Orion will be completed and installed by the end of the year. Processing and testing of the crew module adapter - the ring that connects to the European Service Module - for Artemis II will happen in the first half of the year prior to the arrival of the European Service Module in the fall.

Space Launch System
Training activities with pathfinders, or full-scale replicas, of the SLS core stage and booster segments occurred in 2019, and more training with various pathfinder segments and hardware will continue. In 2020, training will involve stacking inert booster segments on the mobile launcher in the VAB.

Hardware for SLS will continue to arrive for processing and integration in various Kennedy facilities. This year all ten of the solid propellant booster segments will arrive by train from their Northrop Grumman manufacturing facility in Promontory, Utah.

The launch vehicle stage adapter, which will connect the SLS core stage to the interim cryogenic propulsion stage, will arrive by barge. The booster aft skirts - which contain the thrust vector control system that steers the rocket - will trek from the Booster Fabrication Facility to the Rotation, Processing and Surge Facility where they will be attached to the aft exit cones.

The exit cones are attached to the bottommost part of each of the twin boosters to provide extra thrust to the boosters and protect the aft skirts from the thermal environment during launch.

The core stage of the SLS rocket will undergo a Green Run test campaign over several months in the B-2 test stand at the agency's Stennis Space Center in Mississippi. Following Green Run completion, the 225,000-pound core stage will leave Stennis and arrive at Kennedy on the Pegasus barge. The core stage and solid rocket boosters will then be integrated inside the VAB.

Mobile Launcher 2
In 2019, NASA awarded a contract for Mobile Launcher 2 to Bechtel National Inc. of Reston, Virginia. The ground structure that will be used to assemble, process and launch the second and more powerful configuration of the SLS rocket, called Block 1B, is in its early stages of design and development and will be ready for Artemis IV.

Artemis I will be the first in a series of increasingly challenging missions that will enable human exploration to the Moon and Mars. In 2020, the mission will truly begin to take shape as hardware arrives and stacking operations begin inside the VAB.

"The operations team is writing procedures, training, and preparing for flight hardware processing," Bolger said. "When the SLS and Orion are turned over to EGS later this year, Kennedy will be ready!"

Future Artemis missions will establish a sustainable presence at the Moon for decades to come, and Kennedy teams will move forward in 2020 to build the infrastructure and make those missions possible.