Imagine you have packed your bags, said goodbye to your family, done every possible rehearsal, and are sitting at the door ready to leave and then something small goes wrong with your vehicle. You have no choice but to go back inside. That is exactly what happened with NASA's Artemis II mission, the one that was supposed to carry human beings to the Moon for the first time since 1972.
NASA has announced that it is rolling its massive space launch system rocket, along with the Orion spacecraft sitting on top of it, back to its assembly building. The rollback has begun, and because of this, the first crewed Moon mission in over fifty years will now happen not earlier than April.
What makes this even more dramatic is the timing. Just one day before this announcement, NASA was proudly saying it was ready to launch as soon as March 6. The team had just completed a successful wet dress rehearsal on February 19, which basically means they filled the rocket with fuel and ran through the entire countdown without actually launching, just to make sure everything was working perfectly. Everything looked good. The mood was confident.
Then, on February 21, something unexpected happened. Engineers noticed that the helium supply to the rocket's upper stage, the top section of the rocket, was suddenly cut off without any warning.
Now, why is helium so important here? “Helium is not the fuel. It is used to maintain pressure inside the tanks that hold the real fuel, liquid hydrogen and liquid oxygen. Think of it this way: if you want water to flow properly through a pipe, there has to be enough pressure pushing it. The same logic applies here. Without the right helium pressure, the liquid fuel cannot flow properly to the rocket engine. And without that, the engine cannot fire, and the spacecraft cannot move toward the Moon. So a helium problem, even though it sounds small, is actually a very serious matter,” explained space analyst Girish Linganna.
What is particularly frustrating is that this problem did not appear during the big practice test. It was found only later, during routine checks after the rehearsal was over. This means the rocket passed its final big exam but then showed a problem in a smaller follow-up check. Engineers are now carefully going through the helium pipes, a control valve inside the upper stage, and a filter that connects the ground equipment to the rocket, trying to pinpoint exactly where the trouble started.
Until the exact problem is found and fixed, NASA is using a backup system to keep the upper stage safely pressurised so that nothing gets damaged while the rocket waits.
This is not the first time something like this has happened. During the Artemis 1 mission back in 2022, a faulty helium check valve in the same type of upper stage forced NASA to roll the rocket back to the Vehicle Assembly Building. The difference this time is that the 2022 problem was caught during the wet dress rehearsal itself, whereas now it appeared only after the rehearsal was finished.
So why does the rocket need to go all the way back to that building? The Vehicle Assembly Building, the VAB, is one of the largest buildings in the world by volume, standing 525 feet tall. It is the only place where this kind of large-scale repair work can be done safely. The building has giant cranes and a controlled environment that allows engineers to work on the rocket's upper stage without any risk from weather or other outside conditions. There is simply no other option.
“The journey back to the VAB is slow and deliberate. The rocket travels about 6.8 kilometres on a specially built road at roughly 1.6 kilometres per hour. It rides on NASA's giant moving platform called the crawler, which weighs around 3,000 tons by itself and can carry up to 8,100 tons. This machine burns nearly 625 litres of diesel for every single mile it moves. It is just to give an idea of how massive this whole setup truly is,” added Linganna.
Because of the Moon's specific orbital path, Artemis 2 can only launch during a narrow window of a few days, and this window comes around just once every four weeks. The March 6–11 window is now gone. NASA is currently targeting the next window, which runs from April 1 to April 6. If repairs take longer than expected, the delay could stretch even further.
The four crew members, Commander Reid Wiseman, Pilot Victor Glover, Mission Specialist Christina Koch, and Canadian Mission Specialist Jeremy Hansen, have already been released from their pre-launch quarantine and sent back to Houston to wait once more.
