NASA’s Artemis 1 Launch Highlights: Orion is now Moon-bound

Now that Orion has separated itself from ICPS, it will continue on its path towards a lunar distant retrograde orbit, in which it will travel around 65,000 kilometres beyond the Moon, or about 450,000 kilometres away from our planet.  

The Artemis 1 flight test is aimed at demonstrating the performance and gathering engineering data of the SLS rocket and Orion spacecraft. An important part of Orion’s mission will be when it reenters Earth at speeds of more than 40,000 kilometres per hour. 

According to NASA, this lunar velocity reentry is a top mission priority and it will test the performance of the spacecraft’s heat shields. During reentry, Orion will be heated up to nearly 2,760 degrees Celsius, which is about half as hot as the surface of the Sun.

NASA’s launch of the SLS rocket from launch complex 39-B of the Kennedy Space Center as pictured from Sebastian, Florida.

In this image taken from Sebastian, Florida, NASA’s next-generation moon rocket, the Space Launch System (SLS) can be seen taking off with the Orion crew capsule from launch complex 39B of the Kennedy Space Center

After completing the “translunar injection” burn with the interim cryogenic propulsion stage (ICPS), Orion has been put on the path towards the Moon. NASA has confirmed that the spacecraft has separated from ICPS.

The Orion spacecraft completed the perigee raise manoeuvre (PRM) where it fired its ICPS RL-10 engine to raise the lower point of the spacecraft’s orbit (perigee). During PRM, Orion swept its solar arrays back to make sure they don’t sustain any load. The PRM prepares Orion for “trans-lunar injection,” where the spacecraft will put itself on a path to the Moon.

NASA finally gets it right and the Artemis 1 mission's SLS rocket lifted off successfully from Launch Pad 39B at the Kennedy Space Center in Florida. Find out everything that happened during the mission from the beginning of tanking operations at 2 AM IST to launch at 12.17 PM IST. 

NASA said it deployed all four solar arrays on the Orion spacecraft. These will provide the power that Orion requires to leave the lunar orbit and make its way back to Earth. 

Eight minutes into flight, the SLS rocket’s core stage main engines cut off successfully. Then, the Orion spacecraftand the upper stage (interim cryogenic propulsion stage) separated from the core stage.

We are going.

For the first time, the @NASA_SLS rocket and @NASA_Orion fly together. #Artemis I begins a new chapter in human lunar exploration. pic.twitter.com/vmC64Qgft9

— NASA (@NASA) November 16, 2022

The Artemis 1 mission’s SLS rocket lifted off from the Kennedy Space Centre at 12.17 PM IST (1.47 AM EST) on November 16. The successful launch came at the end of a series of technical issues faced by the launch team. All stages of the rocket began using internal power at 12.16 before the rocket’s engines fired for launch.

NASA’s launch team confirmed that it is ready for launch and the launch director completed the final poll, clearing the way for launch. The launch director gave a “go” to resume the countdown and launch the Artemis 1 mission. The mission is now scheduled to launch at 1.47 AM EST. (12.18 PM IST)

The launch team is studying a new issue with the caulk (sealant between the Orion spacecraft and the panels that come off to reveal solar panels. The launch team observed that this caulk is loose and that it could potentially come off.

This is the same issue that was earlier discovered after the Artemis 1 stack weathered Hurricane Nicole. But the mission management team concluded that this presents no additional risk. According to the engineers, the sealant is a loose and pliable material that is unlikely to cause much damage in case it does come off during launch. While NASA is stil yet to confirm exactly when the mission will launch, it said the launch will happen no earlier than 12.15 PM IST. (1.45 AM EST) 

We are now in replenish mode on upper stage for both liquid hydrogen and liquid oxygen. We remain in a hold.

— NASA's Exploration Ground Systems (@NASAGroundSys) November 16, 2022

The Eastern Range confirmed to the launch director that their work on the bad ethernet switch is complete. They are now going to conduct “open loop” tests, which will test the range’s ability to send a destruct signal to the rocket in the case that the rocket goes off-course, endangering the public.

Read this explained article to understand why the Artemis program promises to herald in a new space age. 

A U.S. Space Force Eastern Range officer reported to NASA’s launch director that the faulty ethernet switch that they came across has been dealt with. This malfunctioning system stopped engineers from receiving data from a radar site that was critical to the mission’s flight termination system. At this point, it is unlikely that the mission will launch at 11.34 IST but NASA is yet to confirm how much of a delay should be expected. The launch countdown has been held at T (minus) 10 minutes for a pre-planned hold. 

We are in our planned hold at T-10 minutes. Currently, the upper stage liquid hydrogen is 78% filled. Core stage has been topped off – both liquid hydrogen and liquid oxygen are 100% filled. The ethernet switch has been replaced and will be verified.

— NASA's Exploration Ground Systems (@NASAGroundSys) November 16, 2022

The upper stage is currently in liquid hydrogen fast-fill and is currently at 58 per cent filled. The core stage, in the meanwhile, is in liquid hydrogen replenish mode. Both core stage and upper stage liquid oxygen tanks are in stable replenish mode. Range is currently working on fixing the issue with ethernet equipment.Image credit: NASA TV / YouTube screenshot

The core stage’s liquid hydrogen is once again back in replenish mode after the leak was fixed. The Range safety officer reported to the test director that the problem they flagged earlier was due to a bad ethernet switch. The team is currently working on changing out the switch and “reverifying” it. According to launch control, this work should take around 70 minutes.

Thank you to our 'red crew' team that has completed their work at the pad. We are now back in replenish for core stage liquid hydrogen. Team is working on resuming flow to the upper stage.

— NASA's Exploration Ground Systems (@NASAGroundSys) November 16, 2022

NASA’s Range Flight Safety team has informed the launch director that one of their assets required for launch is down. Meanwhile, the liquid hydrogen replenish valve has been repaired and flow to the core stage’s liquid hydrogen tank has resumed. The team is concurrently working on configuring the upper stage to resume its fuelling.

The ‘red crew’ has left the launch pad. pic.twitter.com/X3w8yP3wEP

— NASA's Exploration Ground Systems (@NASAGroundSys) November 16, 2022

Since the liquid hydrogen tank was put into stop-flow due to the leak, it also stopped the 90-minute liquid hydrogen engine bleed. After discussions, NASA teams have come to the conclusion that only a 45-minute bleed is required at this point and said that continuing the bleed from now would be enough to meet launch requirements.

The red crew has completed their work tightening bolts on the leaky hydrogen valve in the mobile launcher. They have left the launchpad area. 

The red crew team members are still at the mobile launcher where they are tightening bolts on the leaky hydrogen valve. Even though the team said it would take 15 minutes to complete the work, it seems like it will take longer than that.

The red crew is tightening the bolts and then backing out of the area so that the launch team can cycle the valves to make sure the bolts are secured. This will happen repeatedly until the issue is confirmed fixed. It is expected that this work could eat into the launch window, which begins at 11.34 AM IST.

The 'red crew' at @NASAKennedy heading out to the rocket on the mobile launcher at Launch Pad 39B. pic.twitter.com/1EImA7Z6ER

— NASA's Exploration Ground Systems (@NASAGroundSys) November 16, 2022

As the red crew works on fixing the leaky hydrogen replenish valve on the mobile launcher, the weather remains favourable for the mission. There are some clouds in the launch area but they are either too thin or too high up in the atmosphere to cause concern currently.

The red crew team of two technicians and one safety lead has arrived at the launchpad.

Artemis 1 launch director Charlie Blackwell-Thompson gave the “go” for the red team to enter Launch Pad 39B and tighten the bolts on the leaky valve in the mobile launcher. The red crew team is specially trained for completing such dangerous tasks on the launch pad with a tanked vehicle.

Launch Director Charlie Blackwell-Thompson has just given the 'go' for the specialized 'red team' to enter the Launch Pad 39B to tighten bolts on a valve on the mobile launcher.

— NASA's Exploration Ground Systems (@NASAGroundSys) November 16, 2022

The NASA test director briefed the launch team about the plan to send the red crew to the launch pad. The launch team will send two technicians with a safety lead to compartment AB-12, which is on the side of the mobile launcher. They will torque pack nuts to resolve the intermittent leak. 

The technicians will drive two vehicles up the launch pad. After exiting the vehicle, they will go up the stairs to the zero-deck. Then, they will go downstairs to where the leaky liquid hydrogen valve. The red crew told the launch director that this would take them 15 minutes. After fixing the leak, they will return to their vehicles and retrace their route back. Emergency services are standing by for the start of the operation.

The NASA test director is now putting together a plan to send the red crew into the launch area to fix the intermittent leak on the core stage’s liquid hydrogen “replenish” valve, which is inside the mobile launcher. The red crew is a team that is trained to go into the launchpad with a tanked rocket and do work. The leak has reportedly increased.

We have stopped flow of liquid hydrogen to the core stage due to an intermittent leak on the replenish valve. Teams are discussing a plan to send out the 'red crew' to the pad to torque packing nuts at the base of the mobile launcher.

— NASA's Exploration Ground Systems (@NASAGroundSys) November 16, 2022

NASA’s launch team is tracking an “intermittent leak” on the core stage’s hydrogen replenish valve. The leak is located at the base of the mobile launcher. The team reported to the NASA test director that it is going in and out of leak measurement. The leak momentarily spiked to 1.5 per cent but then came down. Going over one per cent leak is considered a “violation mark” but since that happened only momentarily, the mission is still on track.

The launch team has put the fuelling of the core stage into stop-flow mode due to the core stage.If the leak degrades further, they will send the “red crew” to the pad. This is a team that is trained to go into the launchpad with a tanked rocket and do work. Meanwhile, the upper stage’s liquid hydrogen tank is 60 per cent filled while its liquid oxygen is 92 per cent filled.

The core stage sprang a liquid hydrogen leak while it was in replenish mode. (Image credit: NASA TV / YouTube screenshot)

The upper stage’s liquid oxygen tank has been filled and fast-fill is in progress for its liquid hydrogen tank.

Both the liquid hydrogen and liquid oxygen fuelling of the upper stage are in fast-fill mode. The Interim Cryogenic Propulsion Stage, or ICPS, is a modified Delta IV cryogenic upper stage developed for NASA by the United Launch Alliance. It will feed liquid hydrogen and liquid oxygen to the Rocketdyne RL10B-2 main engine, which can produce more than 11,000 kilograms of thrust.

Both the core stage’s have been filled. NASA ground teams are currently in “replenish” mode for liquid hydrogen and liquid oxygen tanking of the core stage, replacing the fuel lost to boil-off. Engineers have now begun fuelling the interim cryogenic propulsion stage (ICPS) tanks.

The core stage’s liquid hydrogen tank has been filled and its liquid oxygen tank is currently 70 per cent full.

The liquid oxygen tank of the core stage is 51 per cent full while its liquid hydrogen tank is around 76 per cent full. Liquid oxygen fast-fill happens at a slower rate than liquid hydrogen fast-fill. In the meanwhile, teams are configuring the upper stage of the rocket, the interim cryogenic propulsion stage. (ICPS) They are configuring its guidance and navigation systems. 

As can be seen from the graphic below, the liquid oxygen tank of the core stage is about 35 per cent full while its liquid hydrogen tank is nearly 40 per cent full.

“We have got about an hour and a half of liquid hydrogen fast-fill to go and about two and a half hours of liquid oxygen fast-fill to go. Things look really good right now,” said Jeremy Graeber, assistant launch director, during NASA’s live coverage of tanking operations.

According to Graeber, the tanking procedures have been updated to deal with the challenges the space agency faced during the earlier launch attempts. During the engine bleed kickstart, engineers noticed a 4 per cent leak of liquid hydrogen. Graeber says this is an expected level of leakage for the engine bleed process. 

NASA teams have begun the engine bleed kickstart on the liquid hydrogen side of the core stage. This kickstart is a pressurised bleed where a vent will be closed to pressurise the tank, allowing a small amount of hydrogen to bleed through the engine. This was when NASA engineers found an issue with one of the core stage’s RS-25 rocket engines during the first launch attempt.

According to Derron Nail of NASA, engineers have filled over 5 per cent of hydrogen and have transitioned into “fast-filling” liquid hydrogen into the core stage. This stage is where leaks have sprung up in the past but the new “kinder and gentler” operation might mean that is no longer the case. After fast fill begins, the teams will begin a liquid hydrogen engine bleed kickstart.

According to NASA, today’s loading operation will be a “kinder, gentler” loading operation compared to the previous two attempts, with the starting pressure on the loading valve lower than usual. The previous two attempts at launching the SLS rocket and Orion spacecraft had to be scrubbed due to issues that surfaced during the propellant loading stage. After the propellant lines are chilled down, engineers will begin “slow filling” the rocket with propellants.

The SLS rocket is in the middle of cryogenic tanking after the launch director gave the “go” for tanking operations. NASA teams have completed chilling down the line for liquid oxygen and are now chilling down the line for liquid hydrogen. They do this so that the lines are suddenly put into thermal shock when the propellants start flowing through them.

NASA’s Artemis 1 mission was initially scheduled to launch on November 16 but the space agency had to postpone it due to tropical storm Nicole. But during the storm, the SLS rocket and the Orion spacecraft were left at Launch Complex 39B of the Kennedy Space Center, where they had to brave the elements. 

Due to this, “several feet of caulk” (sealant) got delaminated at the location where the Orion spacecraft’s launch abort system meets its crew module adapter. In parallel with launch operations, engineers will analyse and assess the risk of this caulk coming loose during the launch. 

NASA is also contending with another issue that was not caused by the tropical storm. According to the space agency, there is also a problem with an electrical connector on the hydrogen “tail service mast umbilical” on the ground-site plate. Engineers have been receiving inconsistent data through the connector despite replacing the cable to it last week. It will not serve as an impediment to the launch since engineers have redundant data sources, but they will still remove and replace a component of the connector.

NASA says that the Artemis 1 mission management team reviewed the status of operations and gave the “go” to begin tanking operations. At the moment, weather conditions are 80 per cent favourable for the two-hour launch window which opens at 1.04 AM EST (11.34 AM IST) on November 16. The biggest weather concern right now is the potential for thick clouds. 

Teams will soon begin loading the Space Launch System (SLS) rocket with liquid oxygen and liquid hydrogen, starting with the core stage before moving on to the interim cryogenic propulsion stage. Click here to read more about what will happen during each stage of the mission countdown.