After two years of circling Bennu, an ancient asteroid (小行星) hundreds of millions of kilometers away, a NASA spacecraft made its way to the rocky surface and collected samples.
NASA spacecraft OSIRIS-Rex was launched in 2016 with the goal of getting samples from the asteroid. On Oct 20, 2020, it was confirmed that 60 grams of rocks had been collected, marking the biggest haul (一次性收获) from beyond the moon.
The spacecraft dropped out of its 750 meter-high orbit and took about four hours to carefully and slowly make it to just above the surface. The OSIRIS -Rex’s 3.4 meter arm, which is responsible for collecting samples, reached out and touched Bennu for about 10 seconds. During the brief touch-down, the spacecraft blasted Bennu’s surface with nitrogen (氮) gas. This stirred up dirt and rock that could then be collected by the arm’s sampling head.
The work behind this process was much trickier than expected. Before OSIRIS-Rex’s launch, data from multiple telescopes showed the asteroid’s surface looked like a beach, full of tiny particles (颗粒) that could be easily collected. However, when OSIRIS-Rex got close enough to take a close-up of Bennu, scientists were surprised by how rough it was and how large the rocks were. The rocky terrain (地形) brought unexpected risks for the spacecraft, so they had to adjust the original plan. The scientists had to add extra software to the spacecraft. Also, they extended the mission time and spent extra time creating a 3D map for Bennu’s surface.
They didn’t have a lot of room for mistakes since OSIRIS -Rex only has three bottles of nitrogen gas. Luckily, after two drills, the spacecraft managed to successfully collect over 60 grams of material.
The sample seems like a small piece of Bennu, but it is a big step for mankind. Bennu was chosen for a reason. The big, black, round, carbon -rich asteroid, which was formed about 4.5 billion years ago, witnessed the solar system’s entire history. With the sample, scientists will explore deeply in labs to find out more secrets about our solar system.
【小题1】The 3rd paragraph is mainly developed _________.| A．by example | B．by process |
| C．by comparison | D．by statistic |
| A．more convenient. | B．more necessary. |
| C．more challenging. | D．more surprising. |
| A．The rocky terrain brought risks for the spacecraft to adjust the original plan. |
| B．It is meaningful for the spacecraft to collect samples successfully from Bennu. |
| C．The carbon-rich asteroid must have witnessed the existence of ancient life. |
| D．We have found some secrets about our solar system by analyzing the sample. |
| A．Asteroid Investigation | B．A Space Exploration |
| C．Making Our Way To Bennu | D．Secrets About The Solar System |
