理工学术英语阅读资源库-Reading 7-Passage One

Please read the following passage and choose the correct answer from the four choices.

The International Space Station (ISS) is a multi-nation construction project that is the largest single structure humans ever put into space. Its main construction was completed between 1998 and 2011, although the station continually evolves to include new missions and experiments. It has been continuously occupied since Nov. 2, 2000.

As of January 2018, 230 individuals from 18 countries have visited the International Space Station. Top participating countries include the United States (145 people) and Russia (46 people). Astronaut time and research time on the space station is allocated to space agencies according to how much money or resources (such as modules or robotics) that they contribute. The ISS includes contributions from 15 nations. NASA (United States), Roscosmos (Russia) and the European Space Agency are the major partners of the space station who contribute most of the funding; the other partners are the Japanese Aerospace Exploration Agency and the Canadian Space Agency.

Current plans call for the space station to be operated through at least 2024, with the partners discussing a possible extension until 2028. Afterwards, plans for the space station are not clearly laid out. It could be deorbited, or recycled for future space stations in orbit.

Crews aboard the ISS are assisted by mission control centers in Houston and Moscow and a payload control center in Huntsville, Ala. Other international mission control centers support the space station from Japan, Canada and Europe. The ISS can also be controlled from mission control centers in Houston or Moscow.

The space station flies at an average altitude of 248 miles above Earth. It circles the globe every 90 minutes at a speed of about 17,500 mph. In one day, the station travels about the distance it would take to go from Earth to the moon and back.

The space station can rival the brilliant planet Venus in brightness and appears as a bright moving light across the night sky. It can be seen from Earth without the use of a telescope by night sky observers who know when and where to look.

The ISS generally holds crews of between three and six people. But crew sizes have varied over the years. The space station has also housed as many as 13 people several times, but only for a few days during crew changeovers or space shuttle visits.

The space shuttle fleet retired in 2011, leaving Soyuz as the only current method to bring people to the ISS. Three astronauts fly to the space station in Soyuz spacecraft and spend about six months there at a time. Sometimes, mission lengths vary a little due to spacecraft scheduling or special events. If the crew needs to evacuate the station, they can return to Earth aboard two Russian Soyuz vehicles docked to the ISS.

Astronauts spend most of their time on the ISS performing experiments and maintenance, and at least two hours of every day are allocated to exercise and personal care. They also occasionally perform spacewalks, conduct media/school events for outreach, and post updates to social media.

The ISS is a platform for long-term research for human health, which NASA bills as a key stepping stone to letting humans explore other solar system destinations such as the moon or Mars. Human bodies change in microgravity, including alterations to muscles, bones, the cardiovascular system and the eyes; many scientific investigations are trying to characterize how severe the changes are and whether they can be reversed.

Astronauts also participate in testing out commercial products – such as an espresso machine or 3D printers – or doing biological experiments, such as on rodents or plants, which the astronauts can grow and sometimes eat in space.

Crews are not only responsible for science, but also for maintaining the station. Sometimes, this requires that they venture on spacewalks to perform repairs. From time to time, these repairs can be urgent — such as when a part of the ammonia system fails, which has happened a couple of times. Spacewalk safety procedures were changed after a potentially deadly 2013 incident when astronaut Luca Parmitano’s helmet filled with water while he was working outside the station. NASA now responds quickly to “water incursion” incidents. It also has added pads to the spacesuits to soak up the liquid, and a tube to provide an alternate breathing location should the helmet fill with water.

NASA is also testing technology that could supplement or replace astronaut spacewalks. One example is Robonaut. A prototype currently on board the station is able to flip switches and do other routine tasks under supervision, and may be modified at some point to work “outside” as well.