Space travel is taking off, but landing on the moon will be no easy feat. The first-ever spaceport could join the moon’s orbit in the next 20 years, increasing space traffic. As a result, plans need to be made to deal with the logistics of several celestial vehicles taxiing and docking at the port and eventually at a permanent moon settlement.
Arrivals and departures
NASA during the next two decades is preparing to implement its Gateway, a small space station designed to be a “multipurpose outpost supporting lunar surface missions, science in lunar orbit and human exploration further into the cosmos,” said NASA. With increased cosmic traffic, there need to be systems in place to manage the flow, according to a study published in the journal Acta Astronautica. The station will become an airport for space travel but “won’t have concrete runways crowded with airplanes, flashing taxiway lights or a crackling voice over an intercom,” said a release about the study.
The Gateway “will not circle the moon the way a satellite circles Earth” and will instead “travel in a near-rectilinear halo orbit, or NRHO, an elongated path shaped by the combined gravity of Earth and the moon rather than by the moon alone,” said Earth.com. The NRHO “passes within 1,000 miles of the moon’s north pole” and then rounds its turn “about 40,000 miles past the lunar south pole,” said Popular Science. The Gateway NRHO “provides an uninterrupted line of sight for communications to Earth and requires little propellant to maintain,” Diane Davis, an associate professor of space engineering at the Texas A&M University College of Engineering and an author of the study, said in the release.
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However, the catch is that any spacecraft that enters the NRHO “will be subject to a gravitational tug-of-war between Earth and the moon,” said the science publication Nautilus. Lunar and space missions are also “likely to involve multiple spacecraft arriving, orbiting and leaving at similar times.” With several crafts, traffic management in the form of loitering, or the “careful choreography of spacecraft positioning,” will be necessary, said the release.
Unlike parking at an earthly airport, vehicles in space require “continuous effort to counteract the forces of orbital physics over extended periods, such as days or weeks,” since each spacecraft is moving constantly, said Universe magazine. Scientists are “required to ascertain a distance that ensures sufficient separation for safety while remaining sufficiently proximate to their destination to optimize fuel efficiency.”
Control tower
To tackle what could be a logistical nightmare, scientists ran thousands of computer simulations to test “strategies for keeping vehicles carefully spaced around Gateway while accounting for realistic navigation errors, thruster imperfections and even small disturbances expected during future Artemis missions,” said the release. They found that “modest increases in station-keeping maneuvers allowed spacecraft to stay significantly closer to their intended positions, requiring only small changes in propellant use.”
The proposal is to “get everything moving together, rather than each spacecraft focusing exclusively on its own path around the moon,” said Nautilus. “By sharing data and continually calculating the position of the Gateway, spacecraft can follow a ‘string of pearls’ formation that keeps everybody at a safe distance.”
The concepts “remain incredibly complex to translate into multibillion-dollar missions with dozens of lives on the line,” said Popular Science. “Greater positional accuracy means mission planners can better predict where every spacecraft will be, preserving valuable fuel,” Davis said in the release. “The future of lunar exploration depends as much on the traffic management as it does on the rocket science.”
