The White House has called for “responsible space behaviours” as a debris from a Chinese rocket, thought to be out of control, is expected to crash back to Earth on Saturday, US time. The US Space Command is tracking debris from the Long March 5B, which last week launched the main module of China’s first permanent space station into orbit. The roughly 30-metre (100ft) long stage would be among the biggest piece of space debris to fall to Earth. The non-profit, federally funded Aerospace Corp has said it expects the debris to hit the Pacific near the Equator after passing over eastern US cities. The orbit covers a swath of the planet from New Zealand to Newfoundland. The US defence department expects it to fall to Earth on Saturday though where it will hit “cannot be pinpointed until within hours of its re-entry”, the Pentagon said. The White House press secretary, Jen Psaki, said on Wednesday: “The United States is committed to addressing the risks of growing congestion due to space debris and growing activity in space and we want to work with the international community to promote leadership and responsible space behaviours.” China’s space agency has yet to say whether the rocket is being controlled or will make an out-of-control descent. But the Global Times newspaper, published by the Chinese Communist party, has claimed the rocket’s “thin-skinned” aluminium-alloy exterior will easily burn up in the atmosphere, posing an extremely remote risk to people. Jonathan McDowell, astrophysicist at Harvard University, has predicted some pieces of the rocket will survive re-entry and that it would be the “equivalent of a small plane crash scattered over 100 miles”. “Last time they launched a Long March 5B rocket they ended up with big long rods of metal flying through the sky and damaging several buildings in the Ivory Coast,” he said. “What’s bad is that it’s really negligent on China’s part. Things more than 10 tonnes, we don’t let them fall out of the sky uncontrolled deliberately.” The Long March 5B rocket carried the main module of Tianhe, or Heavenly Harmony, into orbit on 29 April. China plans 10 more launches to carry additional parts of the space station into orbit. Holger Krag, the head of the European Space Agency’s space debris office, said an Austrian laser station was able to track the falling rocket. The latest data shows it is in an elliptical orbit ranging from 165km to 292km from Earth. It is hard to pinpoint when and where the rocket will come down, but current ESA estimates are between 8 May and 10 May. The rocket’s trajectory means that any parts that survive re-entry will land between 41 degrees north and 41 degreessouth, a strip of Earth that runs from southern regions of Spain, Portugal and Italy down to Australia. Krag said it was not possible to predict how much of the rocket would survive re-entry without having design details of the Long March 5b first stage. “A rough rule of thumb derived from the more detailed analysis of known objects, but not necessarily comparable, suggests that between 20% and 40% of the dry mass can survive,” he said. For the Chinese rocket body, that would be the equivalent of several tonnes. About 150 tonnes of space hardware fall back to Earth each year and so far there have been no casualties. The vast majority plunges into the Pacific. ”This particular case combines quite some of the mass in a single event which is remarkable, but it will not alter the annual risk profile too much,” Krag said. In May 2020 another Chinese rocket fell uncontrolled into the Atlantic off west Africa. It was the heaviest debris to fall uncontrolled since the former Soviet space station Salyut 7 in 1991. China’s first space station, Tiangong-1, crashed into the Pacific in 2016 after Beijing confirmed it had lost control. In 2019 the space agency controlled the demolition of its second station, Tiangong-2, in the atmosphere. In March debris from a Falcon 9 rocket launched by US company SpaceX fell to Earth in Washington and on the Oregon coast.