The Nancy Grace Roman Space Telescope continues its inexorable march toward launch. It recently completed another series of tests that brings it a few steps closer to a launch pad in Florida. This time, the telescope was split into two separate parts - an inner portion and an outer portion, each of which went through separate tests throughout the fall.
The inner portion, which contains the spacecraft’s bus, the instrument carrier, and the telescope itself, underwent a thermal vacuum test. That test is designed to simulate the conditions when it will reach the L2 Lagrange Point - its final observational destination. To be able to pull a thermal vacuum on such a massive structure, over 200 workers had to move the entire assembly to the Space Environment Simulator at NASA’s Goddard facility.
Once the core portion was lowered into the simulator, the team ran tests for two months straight. This included the first time the team turned on the telescope and all the instruments at the same time - the next time will be when it reaches its final destination in space. During the testing, the telescope was subjected to both extreme cold and extreme heat. The side facing the sun can reach up to 150°C, whereas the infrared measurements Roman will take will require some of its instruments to operate as low as -190°C. Both of those extremes can be reached in the simulator, and likely were during the test cycle.
The outer portion of the telescope, which consists of the outer barrel assembly, solar panels, and aperture cover, underwent two separate tests at Goddard - both intended to mimic extreme conditions found only during launch. One was a vibrational test, while the other was an acoustic one.
Acoustic testing is exactly as advertised - workers placed the assembly in a large chamber with a series of horns and hooked a bunch of sensors up to both the assembly itself as well as the chamber. They then ramped up the noise level until they blasted it with a sound equating to 138 decibels for a full minute. The cliche is to describe that level of acoustic energy as “as loud as a jet engine taking off” - but it can also be said that it’s similar to what the band Manowar hit during a soundcheck for a concert in 2008. Not that they would be doing a soundcheck that loud for a full minute - but still, it’s interesting that a band has (likely accidentally) played as loudly as a rocket launch.
Vibrational testing for a system this big is a little more nuanced. It’s no surprise that telescopes shake when they are launched into space - that’s been known, and considered in design specs, for a long time. But mimicking that without actually strapping the unit under test to a rocket is hard. Luckily, NASA engineers have a great tool for the job - a massive shaker table. When the outer part of Roman was placed on it, test engineers ran several series of tests that ramped vibrations from 5 Hz up to 50. Each test only took about a minute, but the data analysis from the sensors placed on the assembly, as well as the fact that they had to run the test on three different axes, meant the test took a number of weeks to complete.
But they did complete successfully, as did all the other tests on both parts of the assembly. That means the Nancy Grace Roman Space Telescope can move on to the next step of its test plan - integration. Over the course of November, team members have been working to integrate the inner and outer portions of the assembly. After that is successfully done, they will move on to some more testing of the fully integrated system before getting ready for launch. As of now, that is still scheduled for sometime around May of 2027, but the mission team believes they might be able to pull it up to as early as next fall. It remains to be seen if the recent government shutdown - or the looming future one that might happen again in February - will have any impact on that optimistic timeline. But at least for now, NASA can say that its next major flagship observatory has passed a critical testing milestone and is on track to be delivered to space in the near future.
Learn More:
NASA - NASA’s Roman Observatory Passes Spate of Key Tests
UT - Roman Telescope Core Components Complete Vibration Testing
UT - The Roman Space Telescope is Coming Together as Engineers Install its Solar Panels