NASA’s Dragonfly Flight System Faces Heat

In preparation for the journey to reach the surface of Saturn’s largest moon, Titan, the heat shield for NASA’s Dragonfly mission completed thermal-structural testing in the New Mexico desert. Dragonfly team members, including those from NASA’s Ames Research Center in California’s Silicon Valley, the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and Lockheed Martin in Littleton, Colorado, collaborated with personnel at Sandia National Laboratories’ National Solar Thermal Test Facility in Albuquerque, New Mexico, to stress-test Dragonfly’s heat shield materials, ensuring the rotorcraft will be safely delivered through Titan’s dense atmosphere.

Dragonfly’s thermal protection material, made from carbon fiber and a lightweight resin, performed as expected in combined mechanical and thermal testing, even in cases when it was intentionally marred with defects.

Sandia’s Solar Tower test facility houses an array of hundreds of calibrated mirror-like systems to focus energy from the Sun onto a tower holding the test unit. Operators generated temperatures around 4,500 degrees Fahrenheit (nearly 2,500 degrees Celsius) on segments of Dragonfly’s heat shield material. Tests examined tolerance to thermal radiation as well as the rapid change in temperature that researchers expect Dragonfly to experience.

The Sandia test series involved multiple iterations in conditions like those expected during Dragonfly’s entry into Titan’s atmosphere. Additional testing subjected large samples of the heat-shield material to mechanical and thermal stress to simultaneously simulate the pressure of high-speed atmospheric entry and intense thermal conditions. Thermal testing of the heat-shield’s curved shoulder units was also performed.

“We were pleased to see the heat shield material pass these tests, even with the flaws we intentionally included, like those that might naturally occur during fabrication and integration,” said Milad Mahzari, the Dragonfly entry vehicle thermal protection system lead at NASA Ames.

Dragonfly’s heat shield uses a variation of a NASA-invented material called PICA, or Phenolic Impregnated Carbon Ablator. The original PICA material was used to deliver NASA’s Curiosity and Perseverance rovers to Mars. PICA-D, a new variant of PICA, is planned for flight on Dragonfly and was the focus of this test series.

“We tested the heat shield as a complete system, including the primary PICA-D material, gap fillers, and potential manufacturing defects,” Mahzari said, adding that researchers plan to conduct additional analysis of PICA-D before final construction of the heat shield begins.

Dragonfly rotorcraft integration and testing continues at APL, which designed Dragonfly and leads the mission for NASA. Dragonfly is scheduled to launch in 2028 and reach Titan in 2034 to conduct science across multiple locations, sample surface materials to measure their detailed compositions, and observe geology and meteorology on the only moon in the solar system known to have a substantial atmosphere.

Communications on board

Work continues to test and integrate Dragonfly’s communications system, including the antennas that will link the rotorcraft to operators back on Earth.

The team recently measured the signal patterns coming from Dragonfly’s largest antenna – its high-gain antenna, or HGA – in an APL test chamber that simulates the space environment. The HGA is a 34.4-inch diameter radial line slot antenna, which uses many small slots working together to create a narrow, focused radio beam.

The technology for this antenna was originally developed for NASA’s DART mission and is also flying on NASA’s twin ESCAPADE spacecraft.

“A simple way to picture the antenna is as a large flat showerhead: energy enters near the center and spreads out through the slots in a controlled pattern,” said Matt Bray, Dragonfly lead antenna designer at APL. “This design provides a low-cost, durable and compact approach to high-efficiency communications in extreme space environments and also provides aerodynamic benefits.”

The HGA, Dragonfly’s primary antenna for transmitting science data, will be attached to the top deck of the lander on a gimbal that allows it track Earth from various locations on Titan’s surface. It will be covered with Kapton, a thermal insulator, for protection from Titan’s weather and crafted to operate in the moon’s frigid environment, where ambient temperatures are 290 degrees below zero Fahrenheit (179 degrees below zero Celsius).

The HGA will be one of three antennas on Dragonfly designed for operations at Titan. The lander will also fly a medium-gain antenna, primarily as a backup to the HGA, and a low-gain antenna, primarily to transmit status tones during flight as well as for emergency communications.