As a team from the Forensic Science Laboratory probes the debris, we take a look at what has been found so far, how it’s different from meteoroid debris, and whether there have been similar incidents in the past in India.

What do we know about the debris?

According to local police, at around 4:45 p.m. on May 12, “the first large black metal ball” weighing about five kilograms fell “from the sky” in the village of Bhalej in Anand, followed by two similar fragments in two other villages – Khambholaj and Rampura. The three villages are located within a radius of 15 kilometers, with a piece of debris falling in the Chimanbhai field. Fortunately, no one was injured, authorities said.

On May 14, similar sphere-shaped debris was reported in Chaklasi village in Anand, about 8 km from Bhalej.

While Indian authorities have released no statement establishing what it might be, astronomer Jonathan McDowell of the Harvard Smithsonian Center for Astrophysics tweeted that it could be debris from the re-entry of the Chang Zheng 3B Y86 series. – the Chinese orbital launcher.

Respond to a query by The Indian Express, McDowell said his inference is based on the fact that this object “is the only re-entry that day (May 12) that went anywhere near India,” based on data from the US Space Force he monitors.

Aerospace.org also predicted the same, saying the launcher will re-enter Earth space on May 12 at around 10:37 a.m. (IST).

However, McDowell adds that “the predicted trajectory was a few hundred miles north of the villages in question, but that remains within the uncertainties for this particular object since its orbit was more uncertain than usual.”

“The problem is that the orbit was changing rapidly due to atmospheric drag. So the last Space Force orbit we had was several hours ago. The forward projection of that orbit is reliable in terms of trajectory in space. But the position of the rocket along its trajectory is uncertain, and you must take into account that if it is five minutes late, the Earth has rotated under the orbit of 5 minutes, which is equivalent at 0.25 degrees in that time frame. As such, the predicted ground location also changes accordingly,” McDowell said.

Gujarat’s Anand district collector, M.R. Daxini, said a team from the forensic science lab is examining the samples and the district collector is “in touch” with the physical research lab in Ahmedabad and the center. Indian Space Research Organization (ISRO) Space Application Center (SAC) to determine whether the debris is from a satellite or a rocket.

The third stage of the Y86 series Chang Zheng 3C rocket, which launched the ZX-9B communications satellite in September 2021, re-entered around 0900-1200 UTC today. (1/2)

—Jonathan McDowell (@planet4589) May 12, 2022

What is space debris?

Space debris can include natural space debris such as meteors, or man-made ones which can include defunct spacecraft and satellites, rocket stages that launched payloads, dead satellites, satellite explosions and collisions.

According to NASA, “more than 25,000 objects larger than 10 cm are known to exist” as space debris and the estimated population of particles between 1 and 10 cm in diameter is around 500,000. NASA, in January 2022, the amount of material orbiting Earth exceeded 9,000 metric tons.

What is Chang Zheng 3B Y86 series, from where the debris is believed to have fallen?

Chang Zheng 3B, commonly known as CZ 3B, is China’s orbital launcher, similar to India’s GSLV or PSLV. “Long March” rockets are a family of carrier rockets operated by the National Space Administration of China, which carry satellites or payloads. The 3B designates the Long March 3B model in this family of rockets.

The model has completed up to 84 flights, the last being in April 2022, carrying communications satellites. Y86 denotes the designated serial number of the 78th flight mission. This mission was launched on September 9, 2021, carrying the 5,500 kg ChinaSat 9B communications satellite to geostationary transit orbit.

Usually, the first and second stages of rockets return to earth after liftoff in about a week due to the release of these stages at lower altitudes. In such cases, the re-entry can then be maneuvered in such a way that it does not affect the populated landmass and does not cause damage. However, the third stage, which releases the satellite into the required orbit after which it remains in suborbital flight, remains out of range of control by human intervention and eventually returns to earth. It is this third stage of the Long March 3B Y 86 rocket launch that is now suspected to have re-entered the earth, causing debris to fall in Gujarat.

The difference in impact between natural and artificial debris

Most space debris burns up when it enters the Earth’s atmosphere, the process beginning at a height of about 100 km from the Earth’s surface to 20 km. However, sometimes very heavy parts may not burn completely and part of the object may rise to the surface, hitting a land mass or body of water.

Notably, with constellation satellites gaining traction such as SpaceX’s Project Starlink, London-based OneWeb’s OneWeb Constellation, and Amazon’s Project Kuiper, the common criticism has been increased space debris and the risk of collision.

In the case of man-made debris, they often disintegrate into fragments, rarely creating a large-scale impact. It’s usually natural debris, such as asteroids and meteoroids, that cause relatively large-scale craters, if they end up hitting a landmass.

How does space debris travel and how is it tracked?

Tracking space debris has become an area of ​​interest for many astronomers. NASA, for example, says that “large orbital debris (>10cm) is tracked regularly by the US Space Surveillance Network” as objects as small as 3mm can be detected by ground-based radars, “providing a basis for a statistical estimate of their number.

In the lower parts of Earth’s orbit (below 2000 km), debris orbits the Earth at speeds of around 7-8 km per second. However, the average impact speed of orbital debris with another space object is about 10 km/s and can be up to about 15 km/s, or about 10 times the speed of a bullet. Therefore, collisions with even a small piece of debris will involve considerable energy.

Estimates of orbital debris population smaller than 1 mm can be by examining impact characteristics on surfaces of returning spacecraft, although this has been limited to those operating at altitudes below 600 km. According to NASA’s Orbital Debris Program Office, “The intentional destruction of the Fengyun-1C weather satellite by China in 2007 and the accidental collision of the American communications satellite Iridium-33 and the retired Russian spacecraft Cosmos-2251 in 2009 significantly increased the number of large debris in orbit — account for a third of all orbital debris listed.

Have there been similar incidents in the past?

In India, a similar event was reported in April this year, when six metal balls and a metal ring, also believed to be from China’s Long Mars 3B rocket, fell from the sky in parts of Maharashtra and Madhya Pradesh. . A team from ISRO was mobilized to determine the specific nature.

McDowell said The Indian Express that third-stage re-entries in populated areas occur “once every few months”.

One event that stands out in terms of space debris damage is that of February 1996. A failed launch of a Long March 3B rocket resulted in debris falling from the satellite’s payload, the American-made Intelsat 708, from the sky a few minutes after takeoff. , which reportedly killed six people and injured 57 others in China, according to the Xinhua news agency. The first reported incident of space debris damage was in 1978 after the crash of the USSR’s nuclear-powered Cosmos 954 satellite, which fell over Canada nearly four months after liftoff, requiring extensive cleanup radioactive materials.

Under the Convention on International Liability for Damage Caused by Space Objects, countries can seek compensation from other countries for damage caused by space debris.

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