1 . Space is where our future is — trips to the Moon, Mars and beyond. Most people would think that apart from comets (彗星) and stars, there is little else out there.     1     Scientists are now concerned that if we don’t clean it up, we may all be in great danger.

The first piece of space junk was created in the year of 1964, when the American satellite Vanguard I stopped operating.     2     However, since it kept orbiting around the Earth without any results, scientists became increasingly comfortable abandoning things that no longer served any useful purpose in space.

    3     The junk varies from tiny pieces of paint chipped off rockets to cameras, huge fuel tanks, and even odd items like the million-dollar tool kit that astronaut Heidemarie Stefanyshyn Piper lost during a spacewalk.

The major problem with the space trash is that it may hit working satellites and damage travelling spaceship. In addition to this, many pieces of junk may crash with each other and break into pieces which fall back to the Earth.     4     Ground stations have been built to monitor larger pieces of space trash to prevent them from crashing into working satellites or space shuttles.     5     They will stop littering in space and to clean up the trash already there.

2 . Do you think alien beings exist somewhere in the universe? It seems like Mars, our closest neighbor, has inspired the most science fiction as the place where aliens are most likely to come from. Recent Mars probes (探测) have shown us that there is no life on that planet—at least not now. But that does not mean that life does not exist elsewhere—after all, the universe is really big. A lot of scientific research is going on in the search for “extraterrestrial life”.

Think about it—why should the seven billion people on this little planet be the only living beings in the universe? It would, in fact, seem logical that this is not the case. So scientific research in this matter is based around the idea of finding other planets that have environments that can support life —environments similar to the Earth. The search is on for the evidence of the existence, or earlier existence of life: from very wise beings to simple organisms (有机物).

So far, there have been a number of theories as to which planetary bodies may have an atmosphere that can support such life and therefore deserve closer attention. As for places within our own Milky Way Galaxy, it has been assumed over the decades that Mars and Venus, as well as some of the moons of Jupiter and Saturn, may have been hosts for life. Now, as technologies have improved and we can obtain measurements of the composition of the atmosphere on extra-solar planets, the chances of finding “alien” life forms are increasing.

There has been a theory that some of the planets in the habitable zone of the red dwarf star Gliese 581 may be able to support life. In 2007, scientists discovered exoplanet Gliese 581c—and felt that its atmosphere was most suitable for supporting life. But further research revealed that it would not. Now, attention has been turned to Gliese 581d, at the outer edge of the star’s habitable zone. The main standards for deciding whether a planetary body can be life-supporting are atmospheric conditions which allow the existence of water. Gliese 581 is about 20. 4 light years away from the Earth, so even if life does exist there, the distance would mean that communication would be unlikely.

Having said this—who says alien life forms (if they exist) need water?

3 . A new study suggests that dark markings on the planet Mars represent sand — not water. The research in 2015 suggested that lines on some Martian hills were evidence of water. Yet American scientists now say these lines appear more like dry flows of sand. If water is present, it is likely to be a small amount. Water in liquid form would be necessary for microbial (微生物的) life.

NASA, the American space agency, said more research is needed. Michael Meyer is the lead scientist for NASA’s Mars exploration programme. He noted that the latest study does not reject the presence of water. But he admitted, “It just may not be as exciting as the idea of rivers going down the sides of cliffs (悬崖).”

The new findings come from a team led by Colin Dundas of the United States Geological Survey. His team measured 151 of these lines in 10 areas. Most of the lines end with slopes (倾斜) between 28 degrees and 35 degrees. These measurements are similar to active sand dunes (沙丘) on both Mars and Earth. A small covering of dust that moves and sometimes becomes lighter might help explain the markings. They usually appear in the Martian summertime, and then disappear until the next year. If these lines are dry, this suggests that recent Mars bas not had large amounts of liquid water. Dundas and his research team say that many questions remain.

“I still think that Mars has great potential for having had life early on in its history,” Meyer said. “As long as that’s true, we also have a reasonable possibility of life still being on Mars. It just happens to be cryptic or well hidden.”

NASA currently has no robotic — either on Mars or in development — with the ability to climb steep slopes. The lack of such equipment has engineers coming up with ideas like Martian helicopters or planes without pilots.

6 . US Space Agency Returns to Mars with InSight Lander

The American space agency’s lander InSight is to arrive on Mars at the end of November, 2018. Unlike NASA’s Curiosity rover, InSight will not move across the planet’s surface. Instead it will become the first spacecraft (航天器) used only for exploring underground. It will study the geography of Mars, searching for signs of Martian (火星的) quakes.

InSight is a project of U.S. and Europe. It is 6 meters long and 1.5 meters wide. It weighs 360 kilograms. InSight’s 1.8-meter robotic arm will put two experiments in place. Both are designed to explore underground of Mars to learn about the inside.

Bruce Banerdt is the lead scientist for InSight. He viewed the spacecraft as a robot that can take care of itself. “It’s got its own brain. It’s got an arm. It can listen and feel things. It pulls its own power out of the sun,” he noted.

Thomas Zurbuchen, one of the heads in NASA, said the results of the InSight project could “change the way we think about the inside of our earth.” But, first, InSight will have to land on Mars undamaged. Since Mars exploration started in the 1960s, only about 40 percent of the explorations have succeeded.

Tom Hoffman is InSight’s project manager. He said earlier successes do not lessen the concerns for each new exploration. “That we’ve done it before doesn’t mean we’re not nervous and excited about doing it again,” he said.

InSight will enter the Martian atmosphere (大气层) traveling at 19,800 kilometers an hour. It will slow for landing on a wide flat area on Mars. If all goes well, InSight could carry out its experiments in about 10 weeks. The InSight project is expected to continue for one Martian year, about two years on Earth.

Water doesn't currently exist on Mars' surface, but it used to. About 4 billion years ago, something happened to Mars' atmosphere, and most of the liquid water     1    （disappear） due to harmful radiation. But some of     2     may still be underground. Could those ancient water holes contain life?

China's Tianwen-1 mission will search     3    the existing water by radar fixed on the rover （月球车）.The European Space Agency's spacecraft found evidence for subsurface water,     4    （use） radar from space, but this will be the first time a rover has searched from the ground.

Tianwen-1 will also give China     5    （value） Mars experience and lay foundation for a sample return mission planned for     6    end of the 2020s. Getting Martian samples back to Earth is a top priority for the scientific community. Despite the impressive advances     7    （make） in placing science instruments on spacecraft, only the technology on Earth,     8    can test samples accurately, is to verify the presence or absence of life in a sample.

As of 2020, only NASA has landed and operated spacecraft on Mars     9    （successful）. More countries exploring Mars means more     10    （opportunity） for global cooperation. Space exploration brings out the best in us all. When more nations work together, everyone wins.