Though NASA's Artemis I mega moon rocket has been dominating the news lately due to its delayed launch, this first stage of the space agency's long-awaited lunar program is fascinating, and controversial, for a number of reasons. 

Here's our list of the seven most essential things to know about Artemis I, beyond the headlines.

It will be the most powerful rocket NASA has ever built

OK, so this might be the one interesting detail about the SLS that's widely known. The SLS used for Artemis I will generate about 15% more thrust than the Saturn V rocket that sent Apollo astronauts to the moon. The Soviet Union did build a more powerful rocket in the 1960s, but all its test flights failed. 

SLS will take the crown for most powerful rocket currently flying away from Elon Musk and the SpaceX Falcon Heavy post-launch, but if Musk's Starship ends up living up to its promise, it may retake that title within a few years. 

It's NASA's first big step toward Mars

The primary goal of Artemis I is to pave the way for astronauts to return to the surface of the moon. This first test flight will send an uncrewed Orion capsule around the moon and test some technology along the way before coming in for a blistering hot reentry through Earth's atmosphere and a splashdown landing.

But the full vision for Artemis involves next putting a lunar gateway in orbit around the moon. This will be a sort of waypoint and miniature space station for future lunar missions. From there the plan is to set up a permanent outpost on the lunar surface. Everything that NASA learns from Artemis is meant to then inform plans for the first missions to Mars in the 2030s. 

This is the only SLS test flight planned

NASA has only planned (and budgeted) for this single test flight before putting humans on the next flight of SLS, expected in 2024. That means the space agency will have to learn everything it can from this one flight and fix any kinks or concerns that arise on the ground before putting astronauts in Orion for Artemis II. 

It will go deeper into space than Apollo 

For Artemis I, Orion travel on a trajectory around the far side of the moon that will carry the vehicle farther beyond our natural satellite than than any Apollo astronauts traveled, or any other spacecraft designed for humans, for that matter.  At its maximum distance from Earth it will be about 280,000 miles (450,600 kilometers) from home. 

It's way over budget and overdue

The SLS was originally expected to cost US taxpayers $10 billion, but the total spent has more than doubled to exceed $20 billion. And that's just for the rocket. Add the cost of developing Orion and the other components of the Artemis program to the tab and it comes to an estimated $93 billion through the 2025 fiscal year, according to a government audit. What's worse, the expected cost per launch of SLS is looking to be about eight times what was initially expected.

Adding insult to fiscal injury, Elon Musk and SpaceX are developing Starship, expected to be a more powerful system with more payload capacity that will feature reusable first-stage boosters for around $10 billion or less. 

Oh yeah, did I mention the US first hoped to launch SLS as soon as 2016? Cost overruns and stretched timeframes are nothing new in the space industry, but in the time we've been waiting for SLS to fly, we've seen SpaceX perform multiple missions with its Falcon Heavy and fly several high-altitude tests of a Starship prototype. 

It uses familiar parts

Adding to the frustration over the long development timeline for SLS is the fact that the main components of the system were taken off the shelf rather than having to be developed from scratch. The Aerojet Rocketdyne RS-25 engines that sent the space shuttle into orbit many times are again being pressed into service for SLS.

Another interesting indication of just how long SLS has been awaiting its first launch is the fact that its core stage flight computer is powered by the same type of CPU that ran the now obsolete G3 Macintosh Powerbook circa 1998. It's important to note the operating system is efficient enough not to require tons of compute power, but still. 

A couple of familiar names are on board

There are no humans on this flight, but there is one ungulate and one member of many families: A plush Shaun the Sheep toy will have a swell view of the moon and Earth from Orion as part of a promotional partnership. 

Amazon's Alexa voice assistant is also loaded into the capsule's computer to see if it might be able to play the role of (a less malicious) HAL-9000 on upcoming crewed missions. NASA will test to see if a modified version of Alexa could help astronauts keep track of Orion's systems in much the same way so many science fiction movies have promised us we'll talk to our spaceships in the future.

The future has arrived. Be sure to keep track of all our Artemis and other NASA coverage as we head back to the moon.