New solar sail technology launches on Rocket Lab flight

by Sawyer Rosenstein

A potential new way to travel through space launched aboard Rocket Lab’s Electron rocket from Launch Complex 1 located on New Zealand’s Mahia Peninsula.

The mission, named “Beginning of the Swarm,” put two payloads into a Sun-synchronous orbit. The flight lifted off at 22:32 UTC on April 23, 2024.

One of the two payloads aboard the mission is NASA’s Advanced Composite Solar Sail System (ACS3). The goal is to test a new composite that can be folded up inside something as small as a CubeSat and still deploy and remain rigid once in space.

For this test, the solar sail is designed to fit inside a 12-unit (12U) CubeSat, which measures approximately 23 by 23 by 34 centimeters (9 by 9 by 13 inches). This is comparable to the size of a microwave.

A solar sail involves deploying a large metallic sheet that acts like the sail on a sailboat. Similar to a boat, it uses a boom to extend the sails. Rather than using chemical or electrical propulsion, these sails use sunlight and solar wind to help push a spacecraft or satellite.

For this mission, flying the sail is objective number two. The first objective is to unfold the entire sail in approximately 25 minutes and see how well it holds up.

Render of the ACS3 solar sail in orbit. (Credit: NASA)

This is where a brand-new composite boom comes in.

Johnny Fernandez at NASA’s Langley Research Center told NSF in an interview that while extendable boom technology has been around for quite a while, it is only now that a small satellite deployment option, made from a polymer material enhanced with carbon fiber, becomes possible.

“By going ultra-thin on the material these days, we can use laminates [and] multi-layer composites that weren’t possible ten or 15 years ago,” Fernandez said.

The composite boom material that is being tested on ACS3. (Credit: NASA)

While foldable booms were used as far back as the Viking Mars lander in the 1970s, they were primarily made of metal. That caused a problem when they experience prolonged exposure to the sun.

“The application of a metallic version has limitations with thermal expansion,” Fernandez noted. “It would deform like a taco-shaped structure.”

The same concern came into play when designing the NEA Scout mission, which flew aboard Artemis 1 but never made contact with ground controllers post-launch.

“Langley had looked at the structural stability, and when we looked at the thermal properties, it became clear that the booms would slowly deform making it unflyable, so that quickly turned into a different study to look into mitigation opening,” Fernandez said.

Another issue arose when looking at how the booms were extended. Fernandez noted that missions like NEA Scout had a membrane split into four, which exposed the metallic booms that could deform.

Teams work on the ACS3 solar sail, open with the new composite booms. (Credit: NASA)

That issue led to the switch to a single membrane. The issue then became where to place the booms and what material to use.

“We had to go from a quarter configuration to a single square to put the booms behind with the sail which will act as a sun shade,” Fernandez said. “That sparked interest to find thermally stable versions of those booms.”

Upon reaching its planned orbit, ACS3 will deploy solar cells, followed by the sail using the four new composite booms over the course of 25 minutes. The rate of deployment will be monitored by multiple cameras to look for efficiency and how well the shape of the solar sail is maintained.

Animation of the deployment sequence of ACS3. (Credit: NASA)

Once unfurled, the square-shaped sail will measure approximately 9 meters (30 feet) per side.

That shape will continue to be monitored as testing begins on using the sail itself.

“If we’re able to deploy and tension that membrane and get that camera data during the event, that’s already a success,” Fernandez said. “The second objective is to use it.”

Another item they had to overcome was the deployment mechanism inside of such a small CubeSat.

As a result, this will only be a 40-percent scale prototype of what NASA plans to use in the future.

“It’s a test of a larger scale system, so we wanted to test the same type of materials that the larger boom structures are supposed to be using by using those same materials to fit into that CubeSat,” Fernandez noted. “We’re really close to the limit of that technology.”

Teams work on the CubeSat from which ACS3 will deploy. (Credit: NASA)

He mentioned that work is underway on versions six times as large as ACS3, and that the sail team is partnering with teams from DLR, the German space agency, to work on the physical deployment mechanism.

According to Fernandez, the technology is now already in use in the commercial sector, including licensing the boom for deployable communications antennae. However, he says NASA has a lot of interest in the material, especially when it comes to the Artemis lunar program.

“[NASA] is using the same type of roller structures to deploy towers on the surface of the moon, including solar panels or deployable antennas to communicate with [the] lunar gateway,” Fernandez said.

The parabolic dishes and reflectors being looked at for the Moon currently use mesh, which Fernandez says creates its own problems.

“Mesh reflectors are prone to dust issues on the Moon, so we wanted a solid surface, like a dish here on Earth…instead creating a parabolic dish that folds like an umbrella,” Fernandez said.

Having tested the materials on parabolic microgravity flights, the team is partnering with businesses and academia to make this mission successful.

Render of the ACS3 solar sail fully unfurled in orbit. (Credit: NASA)

Also along for the ride on this mission is the New space Earth Observation Satellite 1 (NeonSat-1). Developed by the Satellite Technology Research Center (SaTReC) at the Korea Advanced Institute of Science and Technology (KAIST), Korea’s leading science and technology institute, the high-resolution optical satellite will be deployed as a technology demonstration for a planned future Earth observation constellation.

If all goes well with this prototype flight, KAIST plans to mass-produce ten additional satellites, bringing the total constellation to 11. The plan is to have all satellites in orbit by 2027.

Both satellites rode aboard Rocket Lab’s Electron rocket. Flying on the company’s fifth mission of 2024, the nine Rutherford engines on the first stage along with the vacuum-optimized version of Rutherford took care of most of the heavy lifting.

Electron’s payload fairing after encapsulating the NEOSAT-1 and ACS3 payloads. (Credit: Rocket Lab)

This mission included an additional third stage, known as a kick stage. This uses a Curie engine which can be ignited multiple times to help raise and circularize orbits.

Rocket Lab noted that this mission is unique, in that it placed two different spacecraft in very different orbits. So for this flight, the kick stage completed four different burns, including a final burn to speed up its destructive reentry post-satellite deployment.

NEONSAT-1 was deployed into a 520-kilometer (323-mile) circular Earth orbit inclined 97 degrees approximately 50 minutes after launch.

The second payload, ACS3, was deployed into a 1,000-kilometer (621-mile) circular Earth orbit also inclined 97 degrees. This deployment occurred approximately an hour and 45 minutes into the mission.

(Lead image: Teams work on NEONSAT-1 before launch. Credit: Rocket Lab)

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