SALT LAKE CITY — An alternative trajectory developed for a NASA Mars smallsat mission could enable other missions to go to Mars outside the constraints of conventional launch windows.
NASA’s ESCAPADE mission, featuring a pair of identical smallsats built by Rocket Lab for the University of California Berkeley Space Sciences Lab, is now scheduled to launch later this year on the second flight of Blue Origin’s New Glenn rocket. Neither NASA nor Blue Origin have yet offered a specific launch date.
ESCAPADE was originally manifested on the first New Glenn launch but removed from the flight last September when NASA concluded the rocket would not be ready in time before its launch window closed in October. That launch would have sent ESCAPADE directly to Mars.
The mission has since developed alternative trajectories that enable launches outside traditional Mars launch windows, which are open for several weeks once every 26 months. Those involve placing the ESCAPADE spacecraft into Earth orbit or around the Earth-sun L2 Lagrange point before heading out to Mars.
“We can launch on virtually any day” this year, said Jeffrey Parker of Advanced Space in an Aug. 11 presentation at the Small Satellite Conference here. The spacecraft goes into an orbit shaped like a kidney bean around the L2 point, the size of which changes based on the launch date.
A final “loop-de-loop” in that trajectory brings the spacecraft back to Earth, when it performs a maneuver to place it on a trajectory to Mars. The spacecraft would arrive at Mars in mid-2027, around the same time if they took a direct trajectory launching when the next window opens in late 2026.
The same approach could be used for other Mars missions, Parker said. “Can we launch to Mars when the planets are not aligned? ESCAPADE is paving the way for that,” he said.
It does require a spacecraft design with additional propulsion than what’s required for a direct trajectory to Mars. “We still have to boost our energy to leave Earth, so we do have to have fuel on the spacecraft to do that,” he said, estimating it was less than what is needed for a Mars orbit insertion.
ESCAPADE did have that additional performance because in changes in spacecraft design since its selection by NASA in 2019. That included a change to a Rocket Lab bus with chemical propulsion, rather than electric propulsion as originally baselined.
The spacecraft also grew significant heavier, from 165 kilograms to current, fully fueled mass of about 530 kilograms. However, the cost of the mission remained about the same. “Optimizing the system to minimize cost does not always mean minimizing mass,” he said.
That approach could be used to launch a series of smallsats to Mars over a longer period than a conventional launch window, if a mission is limited to a single launch pad.
“If you want to launch many missions from the same launch pad, and the planetary alignment is short, this is an approach where you can launch every couple of weeks and put a fleet of spacecraft into orbit above the Earth,” he said. When the windows open, the spacecraft can then do their maneuvers in a “string of pearls” and head to Mars together. “It’s a way to open up opportunities to use one launch pad to launch many Mars missions.”
The approach has one other advantage, he added. “If you get into space, you’re not going to be canceled nearly as easily than if you’re sitting on the ground.”