Twenty years ago, Congress gave NASA a directive to find 90% of the asteroids that come close to Earth and could potentially harm our little world. Since then, astronomers have made great progress in tracking down rocky space junk, but a new study suggests that there is an entire population of asteroids lurking around Venus that could pose a problem.
These so-called “Venus satellites” share a similar path around the Sun with our neighboring planet, but they are not harmless satellites. According to a forthcoming article in the journal Astronomy & Astrophysics, which is currently available on arXiv, an undiscovered group of asteroids could pose a threat to Earth.
Potentially hazardous asteroids (or PHAs) are asteroids that are larger than 460 feet (140 meters) across and are within 0.05 AU (4.6 million miles, 7.5 million kilometers) of Earth’s orbit.
Valerio Carruba, a researcher at the University of São Paulo, led the study. Carruba’s team suspects that there are more than 20 known coorbiting asteroids of Venus, although they may be even harder to detect.
“Current ground-based observations are limited by periodic observing windows and solar elongation constraints, although the Rubin Observatory may detect some of these objects during favorable configurations,” the team writes in the article. “Space missions based in Venus’ orbits could be useful for detecting Venus’ moons.”
These asteroids also have a so-called “Lyapunov time” of about 150 years, meaning that their orbits become chaotic and unpredictable beyond this time horizon, which on a cosmic scale comes very soon.
To find out if they pose a threat, the researchers created digital clones of the asteroids and conducted orbital simulations covering 36,000 years. In the article, the team writes that “there is a significant population of potential lower eccentricity coorbital asteroids capable of multiple close encounters – and possibly collisions – with Earth.”
However, these coorbiting asteroids are often hidden from the sun’s glare and can therefore only be seen during narrow windows of observation. The upcoming Vera Rubin Observatory, which is expected to begin operations in July 2025, may help to capture some of them. But even Rubin’s extremely powerful camera will not be enough to catch the entire population.
The authors suggest that a space observatory may be the best way to detect any hitherto unobserved asteroids near Venus, either with the help of a constellation or with a single spacecraft.
Since even small asteroids can release energy that can level cities upon impact, the search for these elusive satellites of Venus is not only academically important – it could be vital to planetary defense.
