The last time human beings saw the Moon grow large outside a spacecraft window, Richard Nixon was president, a gallon of petrol cost 36 cents, and the Beatles had been broken up for two years. That was December 1972, when the crew of Apollo 17 fired their engines for home and left the lunar surface behind. No one has been back since. Tonight, at 6:24 PM Eastern from Pad 39B at Kennedy Space Center, NASA intends to change that — launching four astronauts aboard the Space Launch System rocket and Orion spacecraft on Artemis II, a ten-day flyby of the Moon that will carry its crew approximately 7,600 kilometres beyond the lunar far side and back to Earth.

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The mission is not a landing. No boots will touch regolith this time. But Artemis II is arguably the more consequential flight: it is the first crewed test of an entirely new deep-space transportation system, one that must prove itself before anyone attempts to set foot on the Moon again. Every life-support sensor, every communication relay, every navigation algorithm aboard Orion will face its first genuine trial with human lives depending on the outcome.

The Crew

Four People, and a Constellation of Firsts

The crew of Artemis II brings a mix of military test-pilot discipline and scientific rigour to a mission profile that demands both. Together, they represent a series of milestones that the Apollo programme, for all its brilliance, never achieved.

The crew arrived at Kennedy Space Center on Friday, March 27, flying in aboard T-38 jets from Houston. Since then they have been in quarantine inside the Neil Armstrong Operations and Checkout Building — following a controlled sleep and nutrition schedule, completing medical checks, and receiving regular updates on the rocket’s configuration and the weather.

Hey, let’s go to the Moon! I think the nation and the world has been waiting a long time to do this again.

Reid Wiseman, upon arriving at Kennedy Space Center

The Road Here

A Mission Forged by Setback

The path to this launch day has been anything but smooth. Artemis II was originally targeting a February 2026 liftoff, but a cascade of technical problems pushed the mission through three launch windows before reaching today’s date. The delays echo the troubled pre-launch history of Artemis I in 2022, which itself was delayed for years and endured more than two dozen scrubbed or postponed launch attempts before finally lifting off in November of that year.

The hydrogen and helium issues both trace to the same fragile reality: cryogenic rocket plumbing is extraordinarily demanding. Liquid hydrogen, the lightest element in existence, leaks through almost anything. Helium, used to pressurise propellant tanks and purge fuel lines, must flow with precision or the entire upper stage becomes unreliable. NASA Administrator Jared Isaacman identified several possible causes for the helium disruption, including a faulty valve, a problematic ground-to-rocket filter, or an issue with a quick-disconnect umbilical — all problems that could only be diagnosed and repaired inside the Vehicle Assembly Building.

The Flight Plan

Ten Days in Deep Space

If Artemis II launches on schedule today, what follows is one of the most carefully choreographed voyages in spaceflight history — a hybrid free-return trajectory designed to test Orion’s systems at increasing levels of risk while always maintaining a path home.

Launch and ascent (T+0 to T+8 minutes): The SLS rocket’s two solid boosters and four RS-25 core-stage engines generate nearly nine million pounds of combined thrust. Booster separation occurs at roughly two minutes, after which the core stage continues burning for another six minutes. Commander Wiseman monitors the automated ascent from the left seat, prepared to issue an abort command if needed. By main-engine cutoff, Orion will be travelling at nearly five miles per second.

High Earth Orbit and proximity operations (T+50 minutes to T+24 hours): This is the mission’s critical shakedown phase. Two firings of the Interim Cryogenic Propulsion Stage raise Orion’s orbit — first a perigee raise manoeuvre roughly 50 minutes after launch, then an apogee raise about an hour later, pushing the spacecraft into an elliptical orbit with a high point of around 44,000 miles. The ICPS then separates. Pilot Victor Glover moves to the primary controls and manually flies Orion in formation with the spent stage — approaching, circling, and backing away to evaluate the spacecraft’s handling qualities. This proximity operations demonstration is practice for the docking manoeuvres that future Artemis missions will require with the Gateway station and SpaceX’s Starship lunar lander.

Trans-lunar injection (approximately T+25 hours): After the checkout phase, mission control gives the go for the big burn. The European Service Module’s main engine fires to send Orion on a free-return trajectory toward the Moon. From this point, Earth’s gravity will naturally pull the spacecraft home even if propulsion fails — a safety architecture inherited directly from Apollo 13’s emergency return in 1970.

Lunar flyby (approximately Day 5): Orion passes roughly 7,600 kilometres beyond the Moon’s far side — farther from Earth than any human being has ever travelled. The crew conducts observations, science experiments including the AVATAR organ-on-a-chip investigation studying radiation effects on human tissue, and tests of NASA’s Deep Space Network communication capabilities in a region beyond the reach of GPS and near-Earth relay satellites.

Return and splashdown (approximately Day 10): Orion re-enters Earth’s atmosphere at extreme velocity, testing the heat shield under the most demanding conditions it will face before a landing mission. The spacecraft executes a skip re-entry — bouncing off the upper atmosphere once before a final descent — and splashes down in the Pacific.

The Wider Picture

What Comes After the Flyby

Artemis II is not the destination. It is the proof that the vehicle works with people inside it. If this mission succeeds, NASA’s revised Artemis roadmap — announced by Administrator Isaacman in February alongside the programme’s delays — calls for Artemis III to fly next year as a crewed low-Earth orbit rendezvous mission, docking with SpaceX and Blue Origin’s lunar landers to validate systems before anyone attempts a surface landing. Artemis IV and V, both planned for 2028, would then carry astronauts to the lunar south pole. The estimated cost: $20 billion over seven years.

NASA also plans to retire the troublesome Interim Cryogenic Propulsion Stage — the same upper stage responsible for the helium issues that delayed this launch — replacing it with a new second stage for future missions. The agency is designing for a sustained presence on the Moon, not just visits: a base where astronauts could spend weeks or months conducting research and developing technologies for eventual Mars missions.

But all of that hinges on today. On a 322-foot rocket standing on Pad 39B in the Florida dusk. On four people who have spent years training for ten days that will take them farther from home than any human in living memory. And on an 80% favourable weather forecast, with the primary concerns being cumulus clouds, ground winds, and solar weather.

The two-hour launch window opens at 6:24 PM Eastern. If weather or technical issues prevent a launch today, backup windows are available through April 6, and again on April 30. But the intent is clear: the countdown is running, the crew is ready, and after 54 years, the Moon is waiting.

Sources: NASA Artemis Blog, CBS News, CNN, Al Jazeera, NASA, ESA, Space.com, BBC Sky at Night Magazine.