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On November 8, 2020, our planet captured a tiny object – the Centaur upper stage rocket booster that helped lift NASA’s Surveyor 2 spacecraft to the Moon in 1966 – from its orbit around the Sun and will keep it as a temporary moon for about four months before it escapes back into a solar orbit.
This photo shows a Centaur rocket in the upper stage before being coupled to an Atlas booster in 1966. Image credit: NASA.
The Surveyor 2 lunar lander was launched to the moon on September 20, 1966 on an Atlas-Centaur rocket.
The mission was designed for reconnaissance of the lunar surface prior to the Apollo missions which resulted in the first manned lunar landing in 1969.
Shortly after takeoff, Surveyor 2 separated from its Centaur upper stage booster as expected. But control of the spacecraft was lost the next day when one of its thrusters failed to fire, causing it to spin.
The spacecraft crashed into the moon just southeast of the Copernicus crater on September 23, 1966. The Centaur rocket in the upper stage, meanwhile, passed past the moon and disappeared into an unknown orbit around the sun.
In September 2020, the object – initially thought to be an asteroid and with the name of asteroid 2020 SO – was identified by astronomers from the Center for Near-Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory using the Pan- STARRS1 NASA-funded telescope relief.
But the researchers saw the orbit of 2020 SO and suspected it was not an ordinary asteroid.
Most asteroid orbits are more elongated and inclined than Earth’s orbit. But the object’s orbit around the Sun was very similar to that of the Earth.
It was roughly the same distance, almost circular and in an orbital plane that corresponded almost exactly to that of our planet, which is very unusual for a natural asteroid.
As the scientists made further observations on 2020 SO, the data also began to reveal the degree to which solar radiation was changing its trajectory – an indication that it may not be an asteroid after all.
“The pressure of solar radiation is a non-gravitational force caused by the light photons emitted by the Sun hitting a natural or man-made object,” said Dr. Davide Farnocchia, a navigation engineer at NASA’s Jet Propulsion Laboratory.
“The resulting acceleration on the object depends on the so-called area-to-mass ratio, which is greater for small and light, low-density objects.”
On November 8, the Centaur rocket slowly drifted into Earth’s gravitational domain sphere, a region called the Hill sphere that stretches about 1.5 million km (930,000 miles) from our planet.
This is where 2020 SO will stay for about four months before it escapes again into a new orbit around the Sun in March 2021.
Before departing, the object will make two large circles around the Earth, with its closest approach on 1 December 2020.
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This article is based on a press release provided by the National Aeronautics and Space Administration.
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