Why Is Helium Causing Problems with Spacecraft?
2024-09-13
LRC
TXT
大字
小字
滚动
全页
1Helium leaks have been a major problem for spacecraft and rockets.
2Recent reports about Boeing's Starliner and SpaceX's Polaris Dawn mission have involved problems controlling helium.
3Recently, the Starliner had a helium leak in a propulsion system.
4Polaris Dawn also had helium issues on its ground equipment.
5Helium leaks have affected past missions including the Indian Space Research Organization's Chandrayaan 2 and the European Space Agency's Ariane 5.
6Recently, Reuters news agency explored why spacecraft and rockets use helium, and why it can cause problems:
7Helium is inert, meaning it does not chemically react with other substances.
8It also does not burn. Helium's atomic number is 2, making it the second lightest element after hydrogen.
9Rockets need to reach exact speeds and altitudes to maintain their orbits.
10Heavier rockets need more energy to fly and use more fuel.
11They also require more powerful engines, which are costlier to develop, test, and maintain.
12Helium has an extremely low boiling point of -268.9 degrees Celsius.
13This means that it remains a gas even in extremely cold environments like space.
14That is an important quality because many rocket fuels are stored at low temperatures.
15Helium is not toxic.
16But it cannot be breathed on its own because it displaces oxygen.
17Humans need oxygen to live.
18Because of its special qualities, helium is used to pressurize fuel tanks.
19It helps ensure fuel flows to the rocket's engines without stopping.
20Helium is also used for cooling systems.
21As fuel and oxidizer are burned in the rocket's engines, helium fills the resulting empty space in the tanks, maintaining the correct pressure inside.
22Because it is non-reactive, it can safely mix with other contents in the tanks.
23Helium's small atomic size and low molecular weight mean its atoms can escape through small spaces or seals in storage tanks and fuel systems.
24However, because there is very little helium in the Earth's atmosphere, leaks can be easily detected.
25This makes the gas important for identifying possible problems in a rocket or spacecraft's fuel systems.
26In May, hours before Boeing's Starliner spacecraft made its first attempt to launch an astronaut crew, sensors inside the spacecraft detected a small helium leak.
27The American space agency NASA spent several days studying the leak before deciding it was low risk.
28Additional leaks were detected in space after Starliner launched in June.
29Such discoveries played a part in NASA's decision to bring Starliner back to Earth without its crew.
30As a result, two NASA astronauts who flew to the International Space Station aboard a Starliner capsule will need to return to Earth on a SpaceX vehicle early next year.
31The frequency of helium leaks across space-related systems, some engineers say, has shown an industry-wide need for innovation.
32Innovation is needed in the design of valves and the mechanisms that tighten them.
33A valve is a mechanical device that controls the flow of a gas or fluid.
34Some rocket scientists have experimented with gases such as argon and nitrogen, which are also inert and can sometimes be less costly.
35Helium, however, is much more common in the space industry.
36In Europe's new Ariane 6 rocket, designers replaced the helium that was used in the rocket's predecessor Ariane 5.
37The Ariane 6 has a new pressurization system.
38The new system changes a small amount of liquid oxygen and hydrogen propellants to gas, which then pressurizes those fluids for the rocket engine.
39That system failed in space, however, during the final part of Ariane 6's otherwise successful launch in July.
40The failure of the new system added to the international rocket industry's list of pressurization difficulties.
41I'm John Russell.
1Helium leaks have been a major problem for spacecraft and rockets. 2Recent reports about Boeing's Starliner and SpaceX's Polaris Dawn mission have involved problems controlling helium. Recently, the Starliner had a helium leak in a propulsion system. Polaris Dawn also had helium issues on its ground equipment. 3Helium leaks have affected past missions including the Indian Space Research Organization's Chandrayaan 2 and the European Space Agency's Ariane 5. 4Recently, Reuters news agency explored why spacecraft and rockets use helium, and why it can cause problems: 5Why is helium used on spacecraft? 6Helium is inert, meaning it does not chemically react with other substances. It also does not burn. Helium's atomic number is 2, making it the second lightest element after hydrogen. 7Rockets need to reach exact speeds and altitudes to maintain their orbits. Heavier rockets need more energy to fly and use more fuel. They also require more powerful engines, which are costlier to develop, test, and maintain. 8Helium has an extremely low boiling point of -268.9 degrees Celsius. This means that it remains a gas even in extremely cold environments like space. That is an important quality because many rocket fuels are stored at low temperatures. 9Helium is not toxic. But it cannot be breathed on its own because it displaces oxygen. Humans need oxygen to live. 10How is helium used in rockets? 11Because of its special qualities, helium is used to pressurize fuel tanks. It helps ensure fuel flows to the rocket's engines without stopping. Helium is also used for cooling systems. 12As fuel and oxidizer are burned in the rocket's engines, helium fills the resulting empty space in the tanks, maintaining the correct pressure inside. 13Because it is non-reactive, it can safely mix with other contents in the tanks. 14Is helium more likely to leak? 15Helium's small atomic size and low molecular weight mean its atoms can escape through small spaces or seals in storage tanks and fuel systems. 16However, because there is very little helium in the Earth's atmosphere, leaks can be easily detected. This makes the gas important for identifying possible problems in a rocket or spacecraft's fuel systems. 17In May, hours before Boeing's Starliner spacecraft made its first attempt to launch an astronaut crew, sensors inside the spacecraft detected a small helium leak. The American space agency NASA spent several days studying the leak before deciding it was low risk. 18Additional leaks were detected in space after Starliner launched in June. Such discoveries played a part in NASA's decision to bring Starliner back to Earth without its crew. 19As a result, two NASA astronauts who flew to the International Space Station aboard a Starliner capsule will need to return to Earth on a SpaceX vehicle early next year. 20The frequency of helium leaks across space-related systems, some engineers say, has shown an industry-wide need for innovation. Innovation is needed in the design of valves and the mechanisms that tighten them. A valve is a mechanical device that controls the flow of a gas or fluid. 21Can another gas be used? 22Some rocket scientists have experimented with gases such as argon and nitrogen, which are also inert and can sometimes be less costly. Helium, however, is much more common in the space industry. 23In Europe's new Ariane 6 rocket, designers replaced the helium that was used in the rocket's predecessor Ariane 5. The Ariane 6 has a new pressurization system. The new system changes a small amount of liquid oxygen and hydrogen propellants to gas, which then pressurizes those fluids for the rocket engine. 24That system failed in space, however, during the final part of Ariane 6's otherwise successful launch in July. The failure of the new system added to the international rocket industry's list of pressurization difficulties. 25I'm John Russell. 26Nivedita Bhattacharjee reported on this story for Reuters. John Russell adapted it for VOA Learning English. 27______________________________________________ 28Words in This Story 29propulsion - n. the act of driving forward or onward 30mission -n. a flight by an aircraft or spacecraft which has a specific goal 31altitude - n. the vertical elevation of an object above a surface (such as sea level or land) 32toxic - adj. containing or being poisonous material 33detect -v. to discover or find 34frequency -- n. the proportion or percentage of items in a particular category in a set of data 35innovation - n. the introduction of something new 36predecessor - n. one that precedes or comes before 37propellant - n. something that drives forward or onward