(CNN) — Few things are more exciting than watching a spacecraft lift off from the launch pad and set off on a cosmic quest, like NASA’s Artemis I mission is about to do this Saturday.
But if you’re a casual observer, few things may be more confusing than hearing some of the jargon used by mission control.
Celebrities and spectators from around the world will gather at NASA’s Kennedy Space Center in Florida to watch the new Space Launch System rocket and the uncrewed Orion spacecraft make their journey to the Moon.
And for those who cannot attend in person, there will be live broadcasts on various platforms and have been organized watch parties across the country. Many people are trying to distinguish LH2 from LO2 and find out what L minus is.
For those of you who aren’t NASA scientists or amateur astrophysicists, here are some of the terms you’ll hear during the historic launch, and what they mean.
NASA aims to launch Artemis I between 2:17 pm ET and closes at 4:17 pm ET on Saturday, with a reservation window on September 5 in case of bad weather or delays. Shortly before 5:00 am ET, mission managers received weather information and decided to continue fueling the rocket.
As the mission teams count down, they will use phrases and abbreviations that may be unfamiliar. Expect to hear “SLS” to indicate the rocket, rather than Space Launch System, and “rated” to mean things are normal or going according to plan.
When the rocket is loaded with cryogenic (supercold) liquid oxygen and liquid hydrogen to fuel liftoff, the abbreviation is “LO2” for oxygen and “LH2” for hydrogen.
The Artemis launch team will most likely mention “ICPS”, which refers to the intermediate cryogenic propulsion stage. This upper rocket segment will provide Orion with the propulsion it needs in space after the two solid-fuel booster rockets and the core stage, or backbone, of the rocket separate from the spacecraft.
The core stage of the rocket includes the engines, propellant tanks, and avionics, or aviation electronics.
During the countdown, teams will refer to the “L Minus” and “T Minus” times.
“L Minus” is used to indicate the time to liftoff in hours and minutes, while “T Minus” corresponds to the events included in the launch countdown.
If the release team announces a “wait”, this is a natural pause in the countdown to allow work to be done or to wait for a specific release window that does not interrupt the schedule. During a pause, it is expected that the countdown clock and the T minus time will stop, while the L minus time will continue.
Post-launch abbreviations for Artemis I
After launch, the team may refer to the solid rocket boosters as “SRB” and the launch abort system as “LAS.” Two of the launch abort system’s three engines can be used to safely return the Orion crew module to Earth in the event of a system malfunction or failure during launch. The third motor is used to eject the launch abort system, which occurs shortly after launch if all goes well.
Several “burn-ins” are likely to be mentioned, which take place when the propulsion system is turned on, after takeoff.
The “perigee lift maneuver” will take place about 12 minutes after launch. That’s when ICPS experiences a power-up to raise Orion’s altitude so it doesn’t re-enter Earth’s atmosphere.
Shortly after, the “translunar injection maneuver” will take place, in which the ICPS increases Orion’s speed from 28,163 kilometers per hour to 36,371 kilometers per hour to escape Earth’s gravity and head for the Moon. Following this power-up, ICPS will separate from Orion.
Afterward, Orion will perform its first “exit trajectory correction burn” using the European Service Module, which provides the spacecraft with power, propulsion and thermal control. This maneuver will put Orion on its way to the Moon.
During its journey, Artemis I will venture further than the Moon than any other spacecraft intended to transport human beings. It is expected to spend 42 days in space, entering a far retrograde orbit around the moon before crashing into the Pacific Ocean off San Diego on October 10.
It’s just the beginning of the Artemis program, whose goal is to return humans to the Moon and eventually land manned missions on Mars.