The countdown for the launch of NASA’s Space Launch System (SLS) moon rocket officially began just over 48 hours before the six massive engines on the 32-story rocket at last lit at 1:47 a.m. ET this morning, muscling the 2.6 million kg (5.75 million lb.) machine off of launch Pad 39B at the Kennedy Space Center in Florida, and hurling it moon-ward. With the successful liftoff, NASA’s Artemis program—which aims to have Americans back on the moon by as early as late 2025—at last got underway.
In some respects, however, the true countdown for this morning’s launch began on Jan. 15, 2004, when then President George W. Bush announced that the U.S. would be returning astronauts to the moon and called for the construction of a new heavy-lift rocket to make the journey possible.
“The desire to explore and understand is part of our character,” Bush said in a White House speech at the time. “We do not know where this journey will end, but we do know this: human beings are headed into the cosmos.” Exactly 18 years, 10 months, and one day later, that journey—for now without humans aboard—at last began.
The SLS will now make a 25-day journey during which an Orion spacecraft will complete two looping orbits around the moon before returning to Earth for a Dec. 11 splashdown. This morning’s liftoff was bedeviled by last-minute glitches involving a hydrogen leak at the base of the core stage of the rocket and a defective ethernet switch in the range safety mechanism, which would have been used to trigger a self-destruct system if the rocket had gone awry during launch. Repairs on both caused a 44-min. delay in the initially planned 1:04 a.m. ET launch. Once liftoff did occur, the flight went precisely according to the launch controllers plans.
The SLS is a six-engine rocket: its core stage is powered by four liquid fueled RS-25 engines—the same engines that powered the space shuttle. Flanking the core stage is a pair of solid rocket engines—also shuttle legacy hardware. Together, the half dozen engines put out 4 million kg (8.8 million lbs) of thrust, or 15% more than the 3.4 million kg (7.5 million lb.) produced by the Apollo era’s Saturn 5, once the most powerful rocket ever flown—until the liftoff of the SLS this morning.
The solid rocket boosters, which produce 75% of the rocket’s power, …read more
Source:: Time – Science