TECHNOLOGY

March’s Long 5B Missile Stage Makes Fiery Uncontrolled Reentry Over Indian Ocean

HELSINKI — Wreckage from a Chinese Long March 5B rocket first stage made a fiery reentry into Earth’s atmosphere over Southeast Asia on Saturday, six days after the launch of a space station module into orbit.

Debris from the approximately 100 feet long, five feet wide empty and approximately 22 tons nuclear stage of the Long March 5B at 12:45 a.m. Eastern (1645 UTC) July 30, US Space Command announced at 1:45 p.m.

“We refer you to the PRC [People’s Republic of China] for more details on the technical aspects of the reentry, such as possible debris dispersal + impact location, “a US Space Command tweet read.

China’s Manned Space Agency announced minutes later, debris from the Long March 5B re-entered the atmosphere around 12:55 p.m. eastern, with a debris landing area of ​​119.0 degrees east and 9.1 degrees north, in the Sulu Sea, close to Palawan Island in the north. west of the Philippines.

Possible images of the return were posted on Twitter by an apparent onlooker in Kuching, Malaysia, matching the ground track during a 20-minute window of the 18th Space Defense Squadron (18 SDS) Tracking and Impact Prediction message from a US Space Force .

Return appears to have been observed from Kuching in Sarawak, Malaysia. Debris would land down in northern Borneo, possibly Brunei. [corrected] https://t.co/sX6m1XMYoO

— Jonathan McDowell (@planet4589) July 30, 2022

While much of the empty rocket stage is expected to burn on reentry, experts say about 20 to 40 percent of a stage normally survives reentry, such as engine components designed to withstand high temperatures.

NASA administrator Bill Nelson commented on the situation via Twitter shortly after return confirmation.

…reliable predictions of the potential risk of debris impact, especially for heavy vehicles such as the Long March 5B, which carry a significant risk of loss of life and property.

This is crucial for the responsible use of space and to ensure the safety of people here on Earth.

— Bill Nelson (@SenBillNelson) July 30, 2022

The Long March 5B rocket launched on July 24 and sent the Wentian space station module into orbit. Wentian is the second module for the Chinese space station and has successfully docked with the already orbiting Tianhe core module 13 hours after launch.

The Long March 5B is a variant of China’s largest missile. It consists of a core stage and four side boosters. Exceptionally, the first and largest stage of this rocket also acts as the top stage and launches the payload into orbit.

Since the rocket’s YF-77 liquid hydrogen-liquid oxygen engines cannot apparently restart once in orbit, the large first stage is derailed from orbit due to atmospheric drag or an uncontrolled reentry. The vast majority of early rocket stages do not reach orbital speed and fall within a calculated, safe area below launch range.

The Aerospace Corporation, EU Space Surveillance and Tracking (EU SST) and 18 SDS provided regular reentry forecast updates on the Long March 5B as the rocket stage’s orbit fell into disrepair.

China’s manned space agency followed the stage, providing daily updates on the Long March 5B’s basic orbital parameters, but did not provide estimates for its return time.

Where and when the stage would return is impossible to predict with certainty, due to atmospheric fluctuations, the challenges of modeling and unknown aspects of the rocket’s design. Forecasts, however, narrowed possible ground tracks as the runway fell into disrepair and closed the window of uncertainty. The first predictions and margin of uncertainty issued two days after launch were plus or minus 24 hours.

“It is an international custom for the upper stages of rockets to burn up in Earth’s atmosphere,” China’s Foreign Ministry spokesman Zhao Lijian said at a press conference on July 27.

The Aerospace Corporation noted in a press conference on July 27 that about 50 objects weighing more than a ton re-enter randomly each year. However, the exceptionally large tonnage of the Long March 5B means that the missile’s debris posed a relatively high threat.

Ted Muelhaupt stated that the odds of anyone being harmed by this return range from one in 230 to one in 1,000. This does not include the risk of material damage. Muelhaupt added that this was more than an order of magnitude greater than the internationally accepted threshold for uncontrolled missile return of one in 10,000, stated in a 2019 report issued by the US Government Orbital Debris Mitigation Standard Practices.

Meanwhile, the Shenzhou-14 astronauts aboard China’s orbiting space station first entered Wentian at 10:03 PM.

The new module has a series of cabinets for conducting scientific experiments. Wentian will also provide backup life support and propulsion for Tianhe, which launched in April 2021, as well as new work and living spaces and an EVA hatch for astronauts.

“This is the second work and living module we have in the space. The construction of the Chinese space station has taken another big step. We couldn’t be prouder and happier,” Shenzhou-14 mission commander Chen Dong said, according to Chinese state media.

China plans to launch a third module in October to complete the three-module T-shaped space station Tiangong. The mission will again rely on a Long March 5B rocket.

Both Wentian and Mengtian will be transposed from the front docking port of Tianhe to the respective lateral docking ports using a 10-meter robotic arm launched with Tianhe.

China plans to operate the station for at least ten years, with crews of three astronauts lasting six months. It will also launch an orbiting optical telescope module called Xuntian in late 2023 or 2024. It will be able to link to Tianhe for repairs, maintenance, refueling and upgrades, and aims to survey 40 percent of the sky in a decade.

Officials from the China Aerospace Science and Technology Corporation (CASC), the country’s top space contractor, have previously suggested that Tiangong could be expanded to six modules.

China has stated that it welcomes international participation in Tiangong, including payloads through an initiative with the United Nations Office for Outer Space Affairs (UNOOSA), as well as international astronauts and possibly additional modules.

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