Mark Your Calendars–Second SLS Hot Fire Test Now March 18

NASA announced today it will conduct the second Space Launch System (SLS) hot fire test on March 18. If successful, it will be the final step before sending the SLS core stage to Kennedy Space Center in preparation for the first SLS launch.  NASA officials continue to insist that launch could take place this year, but most bets are on 2022.

The Boeing-built SLS core stage, equipped with four Aerojet Rocketdyne RS-25 engines left over from the space shuttle program, is going through a series of eight “Green Run” tests at NASA’s Stennis Space Center in Mississippi.  The hot fire test, where all four engines are ignited as the booster is strapped down to a test stand, is the last.

Ultimately, SLS is designed to be even more powerful than the Saturn V rocket that sent astronauts to the Moon five decades ago. This version is a step in that direction and will send crews in Lockheed Martin-built Orion capsules to lunar orbit where they will meet up with Human Landing Systems (HLS) to take them down to and back from the surface.  A competition is underway to select one or two companies to build HLS vehicles.

NASA attempted the hot fire test on January 16, but computers terminated the test after 67 seconds instead of 485 seconds because of the conservative test parameters that were set.  This is not a test vehicle, but the actual core stage that will be used for the first SLS launch.  NASA needs to ensure the testing does not damage it.

NASA decided to redo the test and scheduled it for February 25, but a problem with a pre-valve forced another delay.

Today, the agency announced March 18 is the new target date, leaving some on Twitter to lament this Green Run test would not be a day earlier on St. Patrick’s Day.

Mark your calendars ?

We are targeting Thurs., March 18 for the second hot fire of the @NASA_SLS core stage at @NASAStennis.

This hot fire is the last test before the #Artemis I core stage is shipped to @NASAKennedy for assembly and integration: https://t.co/kIDyord3Ac pic.twitter.com/fpksvnV2LZ

— NASA’s Artemis Program (@NASAArtemis) March 10, 2021

The test originally was supposed to take place in the fall of 2020, but slipped to January 2021 due to a number of factors including the closure of Stennis Space Center several times last year because of COVID-19 and five hurricanes.

The first SLS launch, Artemis-I, is an uncrewed test flight of SLS and Orion. The first flight with a crew, Artemis-II, is expected in 2023.  Under the Trump Administration’s schedule, in 2024 Artemis-III was to deliver the first astronauts to land on the Moon since 1972.  The 2024 deadline coincided with the end of a second Trump term if he had been reelected and was considered overly ambitious technically and budgetarily by almost everyone.

The Biden Administration supports the Artemis program, but has not indicated what schedule it has in mind.

Congress directed NASA to build SLS and Orion in the 2010 NASA Authorization Act after President Obama cancelled the George W. Bush Administration’s Constellation program.  In 2014, NASA committed  to the first launch in November 2018. That slipped to December 2019-June 2020, then to mid-late 2021.

That plan envisioned completing the tests at Stennis and shipping the core stage to Kennedy Space Center (KSC) in January for mating with the rest of the rocket — the Orion capsule, two Northrop Grumman Solid Rocket Boosters, a Boeing upper stage, and other hardware.

NASA and Boeing officials have said in the past it will take about a month after the hot fire test to have the core stage ready to put on a barge for transportation to KSC. That means it will ship in late April if this test goes well, months later than planned. They have not said how they will make up the lost time and still launch this year, which is why there is such wide-spread skepticism about the date.

Meanwhile, NASA is getting the other parts in place and completed stacking the SRBs yesterday. In December, NASA SLS program manager John Honeycutt confirmed the stacked SRBs have a 12-month time limit before they need to be destacked and inspected, but added they were reviewing that requirement.