Few things are more exciting than watching a spacecraft lift off the launch pad and begin a cosmic quest, as NASA’s Artemis I mission is poised to do on Monday. But if you’re a casual observer, there can be few things 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 uncrewed Orion spacecraft begin their journey to the moon. And for those who can’t make it in person, live streams will be available on multiple platforms, and watch parties have popped up across the country. There are many trying to tell LH2 from LO2 and figure out what in the world L Minus is. For anyone who isn’t a NASA scientist or amateur astrophysicist, here are some of the terms you might hear during the historic launch — and what they mean.
LIFTOFF LINGO
NASA plans to launch Artemis I between 8:33 A.M. and 10:33 a.m. ET Monday — with backup windows on Sept. 2 and Sept. 5 in case of inclement weather or delays. If the launch is “go”, that means things are on track. If it is a “no go”, the launch can be postponed. As mission teams move through the countdown, they will use phrases and abbreviations that may be unfamiliar. Expect to hear “SLS” to indicate the rocket, rather than the Space Launch System, and “nominal” to mean things are normal or going as planned. When the rocket is loaded with cryogenic (supercooled) liquid oxygen and liquid hydrogen for the launch fuel, the abbreviation is “LO2” for oxygen and “LH2” for hydrogen. There is a good chance that the Artemis launch team will mention “ICPS”, which refers to the intermediate cryogenic propulsion stage. This upper section of the rocket will give Orion the propulsion it needs into space after the two solid-fuel rocket boosters and the core stage, or backbone, of the rocket separate from the spacecraft. The basic stage of the missile includes engines, propellant tanks and avionics or avionics. During the countdown, teams will be referred to as “L Minus” and “T Minus” times. “L Minus” is used to indicate the time until liftoff in hours and minutes, while “T Minus” corresponds to the events included in the launch countdown. If the launch team announces a “hold”, it is a physical pause in the countdown intended to allow tasks or wait for a specific launch window that does not disrupt the schedule. During a hold, wait for the countdown clock and the T Minus time to stop, while the L Minus time will continue.
ABBREVIATION AFTER LAUNCH
After launch, the team may refer to the solid rocket boosters as “SRB” and the launch abort system as “LAS”. Two of the three launch abort system 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 engine is used to jettison the launch abort system, which happens shortly after launch if all goes well. Several “burns,” which occur when the propulsion system is activated, will likely be reported after takeoff. The “perigee lifting maneuver” will occur approximately 12 minutes after launch. That’s when the ICPS experiences a burn to raise Orion’s altitude so it doesn’t re-enter Earth’s atmosphere. Shortly after is the “interlunar injection,” when the ICPS increases Orion’s speed from 17,500 miles per hour (28,163 kilometers per hour) to 22,600 miles per hour (36,371 kilometers per hour) to escape Earth’s gravitational pull and to start for the moon. After this burn, ICPS will separate from Orion. Around 4:30 p.m. on Monday, Orion will perform its first “outbound orbit correction burn” using the European Service Module, which provides the spacecraft with power, propulsion and thermal control. This maneuver will put Orion on a path toward the moon. During its journey, Artemis I will venture farther from the moon than any spacecraft designed to carry humans. It is expected to spend 42 days in space, entering a distant retrograde orbit around the moon before launching into the Pacific Ocean off San Diego on October 10. Check out our mission timeline for everything you need to know about the launch countdown and what’s happening during the six-week mission. It’s just the beginning of the Artemis program, which aims to return humans to the moon and eventually land manned missions on Mars.
