SLS and Orion Ready to Roll

SLS and Orion Ready to Roll

NASA’s new Moon rocket, the Space Launch System, topped with an Orion spacecraft, will roll out of the Vehicle Assembly Building at Kennedy Space Center on Thursday. The Saturn-V class launch vehicle will take the 4-mile journey to its launch pad for a test called a Wet Dress Rehearsal tentatively scheduled for April 3 leading up to an uncrewed test flight around the Moon, Artemis I. NASA hopes that will be in the June time frame, the first of three launches to put astronauts back on the lunar surface more than 50 years after the final Apollo crew departed.

Illustration of the Space Launch System and Orion spacecraft. Credit; NASA

Congress directed NASA to build SLS and a “Multi-Purpose Crew Vehicle” in the 2010 NASA Authorization Act.

NASA had been building a big new rocket and crew spacecraft, Ares V and Orion, for President George W. Bush’s Constellation program to return humans to the Moon by 2020 and someday go on to Mars. But President Barack Obama proposed killing the Constellation program in 2010 because it was too expensive. Instead, he wanted to turn human spaceflight over the private sector and skip the Moon, focusing instead on sending people to orbit Mars in the 2030s.

Democrats and Republicans in Congress were furious, having passed legislation in 2005 and 2008 supporting the Constellation program. In addition, if Constellation was cancelled, workers about to lose their jobs as the space shuttle program ended would have nowhere to go. After a bitter dispute, Bill Nelson, then a Democratic Senator from Florida and now NASA Administrator, and Republican Senator Kay Bailey Hutchison of Texas crafted a compromise with the Obama Administration. Do both, but with no extra money. Obama could proceed with commercial crew, but NASA still had to build a big new rocket and spacecraft to send astronauts beyond low Earth orbit — basically the Constellation program without the goal of getting to the Moon by 2020.

SLS thus was born in 2011. It relies heavily on legacy hardware and designs. The Boeing-built core stage is similar to the space shuttle’s External Tank. The Aerojet Rocketdyne RS-25 engines are not simply based on the Space Shuttle Main Engine design, they actually are engines that flew on shuttle flights. The SSMEs were reusable up to 20 times and 16 are left over that can be used for SLS.  Each rocket needs four. The space shuttle’s side-mounted Solid Rocket Boosters had four segments. The SLS SRBs, provided by Northrop Grumman, have five. SLS’s Interim Cryogenic Upper Stage is based on Boeing’s Delta IV upper stage. Orion is new, although development began in 2006 as part of Constellation.

The first flight of SLS/Orion has been delayed again and again. In 2014, NASA committed  to the first launch in November 2018. That slipped to December 2019-June 2020, then to mid-late 2021 and then to 2022.

Now, at long last, they are almost ready to take flight. But first they need to go through a practice countdown  — the Wet Dress Rehearsal (WDR), called “wet” because the rocket is fueled.

On Thursday at 5:00 pm ET, the 322-foot tall stack will begin its slow journey atop Crawler Transporter-2 from the VAB to Launch Complex 39-B. Traveling at less than 1 mile per hour, it will take as many as 12 hours to get there.

Crawler Transporter-2 arrives at the Vehicle Assembly Building at Kennedy Space Center. Inside is the Space Launch System/Orion stack that it will deliver to Launch Complex 39-B. Photo credit: NASA/Chad Siwik

Charlie Blackwell-Thompson, launch director (the first woman to fill that role), told reporters today that if all goes according to plan, the WDR will take place on April 3.

The vehicle was assembled inside the VAB surrounded by scaffolding that is now almost completely removed, allowing a much better view at least of the portion above the SRBs.

The various pieces — the Core Stage (in orange), the Solid Rocket Boosters (obscured by the remaining scaffolding in the photo), the upper stage, the Orion spacecraft, and the Launch Abort System (all white) — were assembled (“integrated”) together in the VAB. Credit: NASA
Components of the Space Launch System and Orion crew vehicle. Credit: NASA

NASA TV will cover the roll-out beginning at 5:00 pm ET on Thursday with remarks by Nelson and other guests. SLS has many critics especially because of its cost, but seeing it roll out for the first time should be quite a sight. As Blackwell-Thompson said today — “breathtaking.”

Artemis I is an uncrewed test flight. Artemis II, planned for 2024, will carry a crew around the Moon. Artemis III will deliver a crew to lunar orbit where they will board a Human Landing System for the trip down to and back from the surface.

NASA hopes that will happen in 2025, which will mark 53 years since Apollo 17 Commander Gene Cernan and Lunar Module Pilot Harrison Schmitt lifted off and Cernan said: “As we leave the Moon at Taurus-Littrow, we leave as we came, and, God willing, we shall return, with peace and hope for all mankind.”

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