The strange space object 2020 SW was discovered on September 17, 2020, as it approached Earth. On November 8, it slowly drifted into the Earth’s sphere of gravitational domination to become a new mini-moon. It will escape back into a new orbit around the sun in March 2021. During this time, it will make two large loops around our planet. In this image, the Earth is the blue dot. The orbit of the moon is the yellow circle. The trajectory of SO 2020 is the pink loop line. Image via Phoenix7777 / Wikimedia Commons.
Astronomers first noticed the object now known as SO 2020 last September. Orbit models quickly showed that both the low velocity and the trajectory of the approaching object were unusual. The models showed that the Earth would capture this object – temporarily – like a new mini-moon. And that’s what happened. 2020 SW has been orbiting the Earth since November 8th. After a more detailed analysis of its motion (and a very close approximation of the object (only 30,000 miles, 50,000 km, or 0.13 lunar distances) on December 1), NASA was able to confirm that the object is a relic of the first space age, a centaur rocket in the upper phase, once called the American Battle Horse in Space. Now by 2020 SW is about to get closer to Earth on February 2, 2021. This time it will go further, but still at 0.58 lunar distances (140,000 miles or 220,000 km). Then, in March 2021, the gravity of the Earth will relinquish its hold on the object.
It will no longer be a mini-moon for Earth. Instead, it will orbit the sun.
You have a chance to see the 2020 OS online. The Rome Virtual Telescope project will show the object online on the night of February 1st. Italian astronomer Gianluca Masi wrote:
We will say goodbye, live: join us from the comfort of your home!
EarthSky 2021 lunar calendars are still available. Order now.
The live feed is scheduled for the night of February 1, 2021, starting at 22:00 UTC (i.e. February 1 at 16:00 Central, at 17:00 East , at 14:00 Pacific in North America; translate UTC at your time). That’s when, Gianluca said, 2020 SO will be at its best above the Virtual Telescope’s robotic telescopes in central Italy. See the poster below for more information and to read more about this event through the Virtual Telescope.
Poster of the online event of February 1, 2021, through the Virtual Telescope.
Astronomers first saw the object on Sept. 17 with the 71-inch (1.8-meter) Pan-STARRS1 telescope in Haleakala, Hawaii. They gave it the designation – 2020 SO – and added it as an Apollo-type asteroid to the JPL small-body database.
However, it was quickly seen that SO 2020 had some features that set it apart from ordinary asteroids. According to NASA / JPL calculations, the object surpassed the Earth’s moon at a speed of 3,025 km / h or 0.84 km per second (0.5 mi / s). It is an extremely slow speed for an asteroid.
These calculations also show the apparent “slow asteroid” orbiting the sun every 1.06 years (387 days). The low relative velocity, along with the Earth-like orbit, suggest that it is an artificial object launched from our planet. Radar images showed that the SO 2020 had an estimated elongated shape of 6 to 14 meters between 20 and 45 feet, a match for the dimensions of an Atlas LV-3C Centaur-D (approximately 12 feet or 41 meters) .
Confirmation that SO 2020 was a lost rocket impulse was found from data collected at NASA’s Infrared Telescope Facility in Maunakea, Hawaii, and from orbit analyzes conducted at the Center for Near- Earth Object Studies (CNEOS) from NASA Jet. Propulsion Laboratory in Pasadena, California. This particular rocket launched the unfortunate Surveyor 2 spacecraft to the moon in 1966.
Paul Chodas, manager of NASA’s Near Earth Object Center at the Jet Propulsion Laboratory (JPL) in Pasadena, California, first suggested that the object could be the lost rocket of Surveyor 2. Surveyor 2 was a probe robotic spacecraft that was launched to the moon on September 20, 1966. It was destined to be the second lunar terrifier of the American unmanned Surveyor program that explores the moon. The spacecraft exploded into space on top of an Atlas LV-3C Centaur-D rocket from Cape Kennedy, Florida.
A mid-course correction error caused the ground controllers to lose contact with the boat three days later, after a propeller did not turn on. The failure caused the spacecraft to fall and eventually fall near the moon’s Copernicus crater.
Unlike some current rocket launchers (which return to Earth and land in ships at sea), the Surveyor 2 rocket remains in space and was lost. It seems to have been pushed from its original trajectory by a small but continuous pressure of sunlight.
It turns out that the missing impeller (now known as 2020 SO) had gone unnoticed on Earth several times in the past, including a close approach in 1966, shortly after its launch.
This 1964 photograph shows an upper stage centaur rocket before being paired with an Atlas booster. A similar centaur was used during the launch of Surveyor 2 two years later and is now known as 2020 SO … a new temporary mini-moon for Earth. Image via NASA / JPL-Caltech.
An Atlas LV-3C Centaur-D was launched on June 30, 1964. Image via AstroNautix.
A model of the ill-fated lander Surveyor 2, which crashed into the moon in 1966. Image via NASA / JPL-Caltech.
How could we have lost an entire 41-foot-long rocket? Space archaeologist Alice Gorman of Flinders University in Australia told ScienceAlert that before our modern era of reusable rockets, rockets launching ships into space were surprisingly easy to lose. She said:
There are so many factors in the space environment, such as gravitational factors and other things that affect motion, that it can sometimes be quite unpredictable.
You need to keep track of these things or you may just lose sight of them very easily. And if they do something a little unpredictable and it looks bad, you don’t know where it’s gone. It’s pretty amazing how many things have gone missing.
NASA explained that the pressure of solar radiation caused the object to change its trajectory:
The pressure exerted by sunlight is small but continuous and has a greater effect on an empty object than a solid. A worn rocket is essentially an empty tube and is therefore a low-density object with a large surface area. Thus, the pressure of solar radiation will push it more than a mass of solid, high-density rock, just as an empty soda can will be pushed by the wind rather than a small stone.
This animation shows the orbit of SO 2020 as it was captured by Earth’s gravity on November 8, 2020. It will escape in March 2021. Its motion has accelerated a million times faster than real time. Image via NASA / JPL-Caltech.
It’s not the first time the Earth has captured a mini-moon.
As you may have noticed, space is full of small asteroids. From time to time, one of these space rocks is temporarily captured by the gravity of our planet before being released back into the solar system in general. Two confirmed mini-moons are 2006 RH120 (in Earth orbit between 2006 and 2007) and 2020 CD3 (in our orbit between 2018 and 2020).
Nor is it the first time we confuse space junk with an asteroid.
Another small object that was initially thought to be an asteroid was the WT1190F, detected in October 2015 as it approached Earth. His trajectory suggested that he was about to penetrate the Earth’s atmosphere near Sri Lanka, in the Indian Ocean, an event that happens with ordinary asteroids several times each year.
As the WT1190F disintegrated in our atmosphere on November 13, 2015, scientists analyzed its light using spectroscopy.
This analysis suggested that the object could be a component of the spacecraft or part of a worn-out rocket, another stray fragment of spacecraft that would return home.
In the case of SO 2020, your return home will not last long. After March, the body of the worn rocket will be on its way again, towards a larger solar orbit. Who knows how long we will keep track of it?
2020 SO is not the first object believed to be an asteroid and then realized it was human-created space debris. Here is an object labeled WT1190F that entered the Earth’s atmosphere in southern Sri Lanka on November 13, 2015. Image via IAC / UAE / NASA / ESA.
Summary: An “asteroid” detected in September 2020 became a new mini-moon for Earth in November. In early December, NASA confirmed that the object was a rocket from the Surveyor 2 mission, originally launched from Earth more than 50 years ago. Now 2020 SO is about to finally approach Earth. This will happen on February 2nd. The night before, on February 1, you can participate in an online viewing of this object.
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Through the Virtual Telescope
