NASA’s Space Launch System may look like a jumble of heritage space shuttle parts, but it’s all new hardware, and the team that made the dual boosters and motors was talking about the challenges of bringing designs from the 1970s into the lunar future.
Northrop Grumman is the company behind the boosters that SLS uses. NASA oversees the work, but, as the SLS Booster Administrator (SLS Booster) said, “It’s all one team.”
It might be one team, but, as Teller also admitted, “I have a small team on the government side, and they have a big team on the contractor side.” This is not surprising, because Northrop Grumman (like a number of other major airlines) receive a significant amount of US taxpayer money and are key to many aspects of the US space program.
record Talk to teams at both NASA and NG, who are responsible for the twin solid rocket boosters that, along with four RS-25 engines, are still on the launch pad in Florida after two failed launch attempts.
It’s hard to avoid thinking of a shuttle stack (just without the shuttle) when looking at the SLS, even though the orange tank sitting between the boosters is an entirely different beast than the previous generation. However, the dual rocket boosters are very heritage parts. However, there are changes. “We’ve done two big things, and a lot of little things,” said NASA’s Teller.
The most obvious big thing is the addition of an additional booster chip: “This gives us 20 percent more power over those boosters,” Teller explained. “I like to joke to my engine buds: ‘You can light all four of your engines and you’re not going anywhere. Once those boosts are lit, they will be gone! “
It’s not really a joke, though, as the manager in charge of the engines called the boosters “runners” while his power units were “mileage runners.”
Solid rocket boosters provide about three-quarters of the SLS’s initial thrust upon launch. Each consists of five parts, the shell designs drawn from the space shuttle era. Doug Hurley, Northrop Grumman’s chief administrator and pioneer of the last space shuttle mission, told us, “Two were aboard STS-135…I traveled with them 11 years ago.”
However, unlike Hurley’s final shuttle mission, these casings wouldn’t float back to Earth via a parachute, and RS-25 engines wouldn’t fly back on the shuttle either.
“It’s mostly a performance” regarding the fate of reinforcements and parachute deletion – one of the big changes, Teller explained. “We have provided eight flight combinations… knowing that we will develop an even stronger booster [Northrop Grumman’s Booster Obsolescence and Life Extension (BOLE) boosters]“This, along with the expected lower cadence of the flight compared to the space shuttle, means that the spent casings will be left to fall into the ocean.
Teller explained, “The more you fly, the more logical the recovery. And it really saves you a lot of money. I wish we’d fly more often,” he added wistfully, “but we’re not…so…”
So boosters become consumable. Or step out in the flames of glory. “It’s great to see them used in this way, as we go back to the moon,” Hurley said.
show must go on
The same goes for the engines, which were previously known as the Space Shuttle’s main engines and are now set to be dropped into the ocean after one final circuit. Production will be responsible for the loss, said Douglas Bradley, deputy program manager for RS-25 at Aerojet Rocketdyne, who had a hand in designing the units in the 1970s. He explained, “We have a total of 16 engines from the Shuttle program, so we can get to the Artemis IV.”
The SLS uses up to four engines per vehicle (up from the three for the Shuttle) and will run at 109 percent of the Artemis I’s estimated thrust. That’s something that was possible in the shuttle days but, like Hurley and Northrop Grumman’s director of business development Rick Masraccio—a Also an earlier shuttle – note that this will only happen in an emergency.
There is room to push things further with the Artemis engine thrust, and Bradley of Aerojet Rocketdyne added: “We’ve run a lot of times at 109, 111 and 113, so we knew they could…”
Why so high? “We know sooner or later we’re going to be running at 111, so our Aerojet Rocketdyne operation has always been 2 percentage points higher than that…You usually have to work a little bit higher to make sure every part has seen that kind of power.”
He said those engines (of which 14 were used on shuttle missions) were a model for reliability during the shuttle’s life, but he admitted some mixed feelings knowing the end was fast approaching. “We’ve been using them for a long time, and we kind of know them. You know – this runs a little warmer. This runs on a more specific impulse (ISP)…So on the one hand, it’s sad, but it’s the coolest thing ever to have some motors worked to take us back to the moon.”
While Northrop Grumman works on the BOLE project to replace heritage SRB booster parts, Bradley has detailed the challenges of reproducing previous Space Shuttle engines. “Some of the things we’ve made in-house – but people have retired. Some of the suppliers we got our machines from – are out of business. So we’ve had to sort of relearn how to make the parts.”
And cheaper, too—Bradley told us that because the engines were consumables, they were expected to be less expensive, though without underestimating reliability or performance. “In some cases, we had changes that we were going to make during the Shuttle program, but we ran out of time. So we incorporated those changes,” he said.
In other cases, modern manufacturing techniques can be used to cut costs – Bradley is a big fan of 3D printing of rocket engine parts, something many other manufacturers use to cut costs without sacrificing reliability.
For other changes, the Aerojet engineer explained that an adaptation program was needed – the Artemis stack is much longer than the Shuttle, for example, and the engines are assembled at the base. This means that the operating pressures will be higher and so on.
While RS-25s will come to life seconds earlier than SRBs, as in shuttle days, their position means the familiar twitching of the shuttle stack, which would tilt slightly when ignited, will go away.
Bradley said, “It was weird seeing her when I first saw her. It would be weird seeing her no [happen]. “
The possibility of reusing heritage shuttle parts has become somewhat moot thanks to the SLS’s low-flying cadence and the need to wrest every last bit of power from what lies in the stockpiles.
While engineers and former astronauts all admitted to having some mixed feelings about using the equipment and then disposing of it, everyone was also visibly happy that instead of gathering dust in the museum, the hardware would be used one last time for so long it had hoped to return to the moon.
NASA said over the weekend that it had decided not to attempt another launch in early September, and You will have to Rotate both the rocket and the spacecraft to the Vehicle Assembly Building after deciding whether work should be done to replace the seal in the panel itself, where it can be tested under extremely cold conditions, or inside the Vehicle Assembly Building.
Because the launch pad is required for a trip to the International Space Station in early October, according to NASA Administrator Bill NelsonThe next launch attempt for Artemis-1 likely won’t happen until a second launch date next month – so anytime from mid-October. ®