A view of Earth from Artemis II. If you can see your region, then you might be able to spot Artemis II with a telescope or binoculars.

Imagine trying to spot a firefly hovering next to a lighthouse from several kilometres away. That's essentially the challenge astronomers face when searching for Earth like planets around other stars. The planet is there, it’s just completely lost in the overwhelming blaze of its host star. Solving that problem is the whole point of a tiny but extraordinarily precise piece of glass called an optical vortex phase mask.

NASA's planned Habitable Worlds Observatory, a future space telescope designed specifically to hunt for signs of life beyond our Solar System, will need to image faint exoplanets directly. To do that, it must suppress incoming starlight by a factor of ten billion. Even a perfect mirror can't achieve that on its own. When light passes through a telescope's circular aperture, it spreads outward into a ringed pattern of light called an Airy pattern, a fundamental consequence of the physics of waves. Those rings can be millions of times brighter than a nearby exoplanet, and they have to go.

That's where the vortex phase mask comes in. Placed at the focal point of the telescope, it applies a carefully engineered delay to the starlight, one that increases continuously as you move around the centre of the mask, like the rising thread of a screw. The result is that the starlight cancels itself out through destructive interference, and what's left can be blocked by a simple aperture stop, leaving only the faint planet light to reach the detector. Light from the exoplanet, arriving at a slight angle, misses the mask's centre and passes through unaffected.

The most promising version of this technology uses a thin layer of liquid crystal polymer, whose long molecular chains can be precisely oriented to manipulate light differently depending on its polarisation direction. Because the delay is produced geometrically rather than by the material's chemical properties, it works across a wide range of wavelengths and that’s crucial for a telescope that needs to analyse the full colour spectrum of a planet's atmosphere.

Live from Kennedy: Artemis II launch coverage is underway. We are tracking every milestone of today's historic launch! Visit our blog for detailed updates:
go.nasa.gov/4v90Ux6

Artemis II will be launching from Florida on April 1st at 22:24 UTC. Watch on NASA's broadcast

The Artemis II astronauts, now suited up for launch, are headed to the launch pad.

The crew includes NASA astronauts Astro Reid, Victor Glover, and Christina H Koch, and CSA ASC astronaut Jeremy R. Hansen.

The Artemis II crew is boarding Orion. 

Reid, Victor, Christina, and Jeremy are taking their seats atop the most powerful manned rocket ever built. They have trained for years for this moment, and now they are preparing to execute a mission that will take us back around the Moon and begin the next chapter of human space exploration.

The hatch is now closed.

The Artemis II astronauts are now strapped into their seats and ready for launch.

Science is a key part of Artemis II

Watch as NASAScience’s Dr. Nicky Fox, breaks down the science of this historic mission that will pave the way for future human exploration of the Moon, Mars, & beyond.

Tune in to the broadcast: youtube.com/watch?v=Tf_UjB…

Teams are troubleshooting an issue with a LAS (launch abort system) battery on the vehicle being outside the acceptable range. If unresolved, this could trigger an abort criteria closer to launch. The range remains green and the timeline is progressing towards Artemis 2.

Europe keeps a close eye on the countdown to the Artemis II launch too.

At European Space Agency's facilities in the Netherlands, teams from the European Service Module are already on console for the 10-day mission.

All systems are GO from the Eagle room, Europe’s mission evaluation hub.

Artemis II update from NASA summarised:
• Vehicle successfully configured for flight
• Issue with battery won't affect launch
• Weather is 90% go for launch

NASA has not set a new T-0 but the Artemis II mission will not launch at 6:24 pm ET today. “A little more work” to do.