On November 16th, 2022 NASA launched what is – for a time at least – the world’s most powerful rocket, the Space Launch System (SLS), on its maiden flight. The uncrewed mission marks the first flight of a human-capable vehicle to the vicinity of the Moon under the aegis of NASA’s Project Artemis.
Lift-off came at 06:47 UTC on the morning, and the rocket – roughly the size of the Apollo Saturn V but massing around 400 tonnes less and with engines generating 5 meganewtons greater thrust – was no slow climber like Saturn V; instead it fairly leapt into the night sky, thundering from 0 to 120 km/h in just a handful of seconds as it lifted an Orion capsule and service module away from the launch pad and on their way to orbit.
It was actually a launch that also nearly didn’t take place (again); during fuelling operations immediately ahead of the launch, a leak was detected. Such leaks have been the bane of this rocket’s existence, and for a time it was uncertain if NASA would stop or delay the fuelling operation – and even scrub the entire launch attempt.
Instead, a risky decision was taken to send in a Red Team to Pad 39B at Kennedy Space Centre to try to fix the leak with the liquid hydrogen propellant feed at the base of the rocket, even with propellants in the tank and the risk of a spark causing an explosion. The team – engineers Trent Annis, Billy Cairns and Chad Garrett worked under the “living” rocket – these monsters do not stand quietly when even partially fuelled, they creak, groan and periodically vent excess gasses – to tighten the “packing nuts” designed to hold the seals on the propellant feed line tightly in place. The crew arrived on the pad just 3.5 minutes ahead of the launch and had to work fast to fix the issue if a launch scrub was to be avoided.
Obviously, the team was successful – which does not lessen the risks they took as unsung heroes of the launch – and at 07:01 UTC, the Interim Cryogenic Propulsion Stage (ICPS) upper stage of the rocket placed the Orion vehicle in an initial orbit, and just over 30 minutes afterwards, the Orion service module successfully deployed the four solar arrays required to provide it and Orion with electrical power.
An hour later, after raising Orion’s orbit, the IPCS stage re-lit is engines to propel Orion from Earth orbit and into a trans-lunar injection orbit at 08:37 UTC, the stage separating from the space vehicle at 09:13 UTC.
Since then, the mission has progressed precisely as planned. At 14:30 UTC, Orion completed its first engine burn, correcting its flight to the Moon, and then late in the day a camera mounted on one of the service module’s solar panels captured a shot of Earth as seen from the vehicle, already almost some 92 thousand kilometres from Earth. On November 18th, the vehicle returned a further image of Earth – in greyscale – as it reached the 299,000 km from Earth mark.
The next major milestone for the flight comes on Monday, November 21st, 2022, Orion will complete the first stage of its leisurely, widely-curved outbound flight to the Moon. At 12:44 UTC on that day, with the vehicle passing around the far side of the Moon at a distance of 130 km, the vehicle will undertake a 2.5 minute burn of its main engine to direct itself into a distant retrograde orbit (DRO) which will carry it as far as 432,000 km from Earth.
The critical aspect of this manoeuvre is that it will occur when the vehicle is out-of-communication with Earth, thanks to the Moon being in between. The entire manoeuvre will therefore be carried out entirely by the onboard flight systems.
The flight so far has tested almost all of Orion’s flight, navigation and other systems, with only 13 issues, the majority defined as “benign”, being recorded. The most significant issue has been the star tracker – part of the flight navigation system. This was getting “dazzled” by thruster plumes as the vehicle adjusted its orientation during flight. While the tracker itself was designed to ignore the plumes, their brightness did confuse the flight software – something that hadn’t been considered could happen during testing. However, now it has been identified, the problem can be dealt with by Mission Control.
More substantial damage was actually done by the rocket itself at launch; the sheer power on the four RS25 engines and two solid rocket boosters did unspecified, but apparently extensive, damage to the mobile launch platform and launch tower. How much damage they sustained is unclear, but Pad 39B has been known to cause launch platforms using it damage. This was particularly noticeable following the launch of Apollo 10 in ay 1969 and again with the Ares 1-X launch in October2009 which resulted in some US $800 million in damages to the pad, platform and tower – although this was in part due the vehicle having to be launched slightly off-vertical, resulting exhaust plume physically striking the tower.
As I noted in my previous Space Sunday report, Orion is carrying a range of experiments onboard, all of which are being monitored throughout the flight. Chief among these are the radiation experiments which will come into their own as the vehicle enters its extended orbit around the Moon, where it will remain through until it again uses the Moon to swing itself back onto a return course to Earth in December 2022.
If you want to interactive track Artemis 1, you can do so via NASA’s Artemis Real-time Orbit Website (AROW). In the meantime, the video below captures the stacking of the Artemis 1 SLS vehicle inside the Vehicle Assembly Building at Kennedy Space Centre, together with the original roll-out to the pad earlier this year, and the night-time roll-out ahead of the launch, together with the initial phase of the mission’s ascent to orbit.
Continue reading “Space Sunday: Artemis rises, a star is (almost) born”
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