NASA is once again sending scientific missions to the Moon. But under the new commercial framework for getting there, researchers need to invent a new method for how to pick where to land.

A New Process for Picking Sites

NASA’s Commercial Lunar Payload Services program is a bold innovation in organizing robotic missions to the Moon. Under this model, rather than keeping the mission process entirely in-house, the agency selects the scientific mission they want to support then simply buys a ride to the lunar surface from a commercial vendor. But, how do you pick a landing site before you know exactly how you’re getting there?

The Lunar Vulkan Imaging and Spectroscopy Explorer (Lunar-VISE) mission, set to launch in mid-2028, was one of the first programs to go through this new landing site selection process. After being officially selected in 2022, the team had just nine months to nail down exactly where their mission should touch down. A recent article led by Jean-Pierre Williams (University of California, Los Angeles) detailed exactly how the team accomplished this task and presented some lessons they learned along the way.

No Parking Lots on the Moon

Picking a landing site is no small task: for context, selecting the landing sites for each of the most recent Mars rovers took five years and multiple community workshops. The Lunar-VISE team therefore took a streamlined and logic-driven approach. They started by explicitly laying out their science objectives: Lunar-VISE’s purpose is to investigate some strangely silicate-rich volcanic formations called the Gruithuisen domes, so they had to land either on or near those. They also had to have access to boulders that were excavated from deep within the domes during a crater formation event, so they had to pick a spot with boulders relatively nearby.

In addition to objectives, they also laid out a slew of constraints. Although they needed boulders nearby, they couldn’t have too many boulders, or any particularly large boulders, since those could pose hazards for landing. There also couldn’t be any steep slopes in the field. Most of the area had to maintain a line of sight with a supporting orbiter for communications, so they couldn’t set down near any ridges. Also, they had to consider how the terrain would cast shadows as the lunar day progressed, since they didn’t want their mission cut short by freezing temperatures and a lack of solar power. As the team quipped, “many interesting, high-science value locations on the Moon may not be in proverbial ‘parking lots.'”

By combing through archival data and working with the team that operates the Lunar Reconnaissance Orbiter Camera, a key asset for making detailed maps of the Moon, the researchers found the perfect spot: alongside a 190-meter-diameter crater named Mareta. This feature is named after Mareta West, one of the first female planetary geologists at the United States Geological Survey and the scientist who selected the landing site for Apollo 11’s historic touchdown.

In addition to presenting their landing site, the researchers offered a handful of lessons to others who may someday be in the fortunate and thrilling position of needing to pick a landing spot on the Moon. For one, they urged teams to coordinate with the Lunar Reconnaissance Orbiter specialists as early as possible, since processing the imaging data for lander-quality maps is a specialized and intensive task. For another, they recommended that all of the software tools used be made publicly available so that future missions don’t need to duplicate their work.

As this article laid out, the Commercial Lunar Payload Services program and Lunar-VISE take us one step closer to making missions to the Moon routine — but we’re still figuring out exactly how to do that.

Citation

“Lunar-VISE Landing Site Selection and Characterization at Mons Gruithuisen Gamma,” Jean-Pierre Williams et al 2026 Planet. Sci. J. 7 161. doi:10.3847/PSJ/ae7d2c

The post Putting the Landing Site Before the Lander appeared first on AAS Nova.

Microlensing surveys have discovered plenty of regular exoplanets, but more surprisingly, they’ve also turned up many solo Neptunes with no star nearby. New research suggests that first impressions might be deceiving, however, and that at least some of these planets might not be so alone: they just have a complicated family history.

An Abundance of Exo-Neptunes

There are simply too many Neptune-like exoplanets in our galaxy. Or at least that’s the current feeling astronomers get from gravitational microlensing surveys, which look for exoplanets during short-lived magnification events caused by chance alignments between stars. These surveys have now found about a dozen so-called “free-floating” planets, and while this doesn’t sound like that many, running the numbers reveals that this tiny sample implies that there are about two free-floating Neptune-size planets for every star in the galaxy.

The idea that there are more free-ranging Neptunes than stars is unsettling, and astronomers aren’t yet sure how this many planets ended up so isolated. It’s possible that these objects simply formed disconnected from any planetary system, but it’s unclear how something so small could collapse from the interstellar clouds that usually produce stellar-mass objects. It’s also possible that the planets formed around stars in the usual way, only to be later kicked out by some violent dynamical process — but this would either require too much time or too many giant planets capable of ejecting the lower-mass ones.

However, new research by Sam Hadden (Canadian Institute for Theoretical Astrophysics) and Yanqin Wu (University of Toronto) presents an alternative idea: what if at least some of these free-floating planets aren’t fully on their own, but instead remain estranged but weakly bound to their parent stars?

Simulated Scattering

Two celestial objects need to align nearly perfectly in order to create a microlensing pulse that we can detect. For an exoplanet orbiting a star, we should observe two of these pulses: one when the host star drifts in and out of alignment with a background star, and one when the nearby bound planet does the same. In the case of a free-floating planet, there’s only one pulse, and we therefore assume that there is no host star. Hadden and Wu noticed that since the alignment has to be so precise for microlensing to occur, it’s possible that a seemingly free-floating planet is simply widely separated from its host star, and the star managed to dodge the magnification effect. In other words, these planets might not be free floating at all, just on wide and eccentric orbits.

The researchers decided to test whether it’s possible to create these kinds of orbits via a known dynamical process called planet–planet scattering. As the name implies, during this process, planets that begin on orderly orbits around their parent star undergo a dramatic rearrangement as they jostle each other around through gravitational interactions. The researchers created two types of simulations: one with a collection of equal-mass planets, and another in which one planet dominates over a brood of smaller ones. After setting up the systems, they let the “dynamical havoc” proceed for a few hundred million years, then surveyed the aftermath.

They found that both types of simulations readily created the “detached” objects needed to mimic free-floating planets. In fact, the most common outcome was for two or three planets to be bullied into far-out orbits by a planet that then plunges onto a tight inner orbit extremely close to the star.

Though the authors caution that this process likely doesn’t explain all of the free-floating planets observed to date, this is an exciting model that would dramatically lower our estimates of the number of Neptunes roaming alone between the stars.

Citation

“Free Floating or Merely Detached?,” Sam Hadden and Yanqin Wu 2026 ApJ 1000 70. doi:10.3847/1538-4357/ae6508

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