Ready to assemble (almost): NASA’s Artemis 1 and load cells

Published On: December 10 2020


How do you assemble a space rocket? According to NASA’s latest update on the Artemis 1, very very carefully – and slowly.

As NASA themselves explain,

“Artemis I, formerly Exploration Mission-1, will be the first integrated test of NASA’s deep space exploration systems: the Orion spacecraft, Space Launch System (SLS) rocket and the ground systems at Kennedy Space Center in Cape Canaveral, Florida. The first in a series of increasingly complex missions, Artemis I will be an uncrewed flight test that will provide a foundation for human deep space exploration, and demonstrate our commitment and capability to extend human existence to the Moon and beyond.”


The launch involves the building of the “most powerful rocket in the world”, currently being assembled at Kennedy Space Center (KSC) in Florida, USA. The launch is scheduled for November 2021, but that deadline involves stacking eight Booster motor segments on top of two foundation element of the whole vehicle, the SLS aft booster assemblies.

How do they do that?

Now bear with us here. NASA adores their acronyms and their latest Artemis update article describing the process of essentially assembling a very expensive set of stacking cups runs to a rather rambling two pages.

First, all the Space Launch System (SLS) Booster elements were shipped from Utah to Florida. Once unloaded they were moved to the Vehicle Assembly Building (VAB). The first two foundation elements were placed on the Mobile Launcher-1 (ML-1) in VAB High Bay 3. These foundation boosters have a skirt on which most of the weight rests. So the skirts in turn sit on eight vehicle support posts (VSP) on the ML, four per booster. These posts are designed to support the vehicle until takeoff, and remain on earth once the rocket has lifted off.

Now the stacking can begin, starting with the left aft centre segment of the rocket. This will be transported on a pallet from its testing location in the Rotation Processing and Surge Facility (RPSF) building to the VAP and put down “In the middle or where ample space is allowable”, as Erik Tormoen, NASA EGS Operations Project Engineer, said.


Load cells swing into action

It’s a this stage that the load cells come into their own, as part of preparations to crane the section into place. This involves “Lifting up the 384 beam, taring out the weight on the load cells, making sure everything reads zero, making sure all the systems on that load beam and on the SSET (SRM Stacking Enhancement Tool), which is an enhancement tool for stacking, are working correctly.”

So, joining the first two elements is a case of lifting the upper section “up and over”, and lowering it done – very slowly. As Tormeon says:

“It’s so slow; I believe it’s like six-thousands of an inch. It’s so slow that you look at it and you can’t tell it’s moving, but it is.”

Whilst all this is going on, the forward assemblies are ready and waiting to be added, stored in a temperature and humidity controlled environment. When they are finally lowered into place, or mated, load cells will be used to gently ease the boosters apart to allow extra clearance.

As Tormeon explains:

“(This is) a strap with a load cell and a position indicator so we can understand how hard we’re pulling on those boosters. We want to get a little room for the mate, but we don’t want to pull too hard and cause stress on the vehicle. So we have added a load cell, and we have a position indicator as well to make sure that we are where we want those boosters to be to allow for that mate.”


And if all that seems a lot of effort just to assemble a rocket, bear in mind that the Artemis 1 assembly will enable Orion to travel 280,000 miles from Earth, way beyond the Moon, and return home “faster and hotter than evert before”.


Artemis 1: the movie

For an overview of the whole Artemis 1 mission, check out this NASA video. (It’s eight minutes long, so you might want to grab a coffee first…)


If you need load cells to assemble your own space vehicle, or any other lifting task involving precision measurement or monitoring, you can: