Science
A large piece of a Chinese rocket is expected to crash to the earth but where exactly?
This weekend, debris from a Chinese rocket is set to re-enter the atmosphere in an unregulated manner.
Last month, the main portion of China's latest space station, the Long March-5b, was used to deploy the first module.
It is one of the biggest objects to have an undirected dive into the atmosphere in decades, weighing in at 18 tonnes.
The US announced on Thursday that it was keeping an eye on the object's trajectory but had no intention to shoot it down at this time.
"We're hopeful that it will land in a place where it won't harm anyone," US Defense Secretary Lloyd Austin said. "Hopefully in the ocean, or someplace like that."
The most likely time of re-entry, according to various space debris modeling experts, is late Saturday or early Sunday (GMT). However, those forecasts are inherently risky.
The Long March-5b core stage, which was inserted into an elliptical orbit approximately 160km by 375km above Earth's surface on April 29, has been losing height ever since.
The density of air it experiences at altitude, as well as the amount of drag it creates, will determine how rapidly the core's orbit continues to decay. These particulars aren't well known.
Our latest prediction for #LongMarch5B CZ-5B rocket body reentry is 09 May 2021 04:19 UTC ± 8 hours along the ground track shown here. Follow this page for updates: https://t.co/p2AU9zVEpA pic.twitter.com/rsE6yzcnHb
— The Aerospace Corporation (@AerospaceCorp) May 7, 2021
While metals with high melting points and other resistant materials will survive to the surface, the majority of the vehicle should burn up as it makes its final plunge through the atmosphere.
A year earlier, piping thought to be from the rocket was discovered on the ground in Ivory Coast, Africa, after a similar core stage returned to Earth.
The odds of being struck by a piece of space debris are very remote, not least because the ocean covers so much of the Earth's atmosphere, and the land has vast swaths of land that are uninhabited.
Latest TIP (as of 2021-05-08 0222Z) for CZ-5B (#LongMarch5B) (48275 / 2021-035B) shows projected re-entry at 2021-05-09 0252(UTC) +/- 360 minutes at latitude -39.4 longitude 180.5.
— Space-Track (@SpaceTrackOrg) May 8, 2021
NOTE: Still not a reliable time or location, given the large window; both will still vary wildly
The trajectory of the rocket stage restricts the possible fall zone even further in this situation. It's heading with a 41.5-degree inclination to the equator. This assumes that any debris falling further north than 41.5 degrees North latitude or further south than 41.5 degrees South latitude can now be ruled out.
