A high level of methane (甲烷) gas on Mars was found by NASA's Mars exploration vehicle. The discovery is exciting because the presence of methane gas could support the case for life on Mars:

NASA's Curiosity vehicle recently recorded the largest level of methane ever measured during its seven-year Mars mission.

Methane has no color or smell. A special instrument on Curiosity's Mars Science Laboratory recorded the increased gas level. Besides methane, the instrument can record levels of water and carbon dioxide.

Nearly all the methane gas found in earth's atmosphere is produced by biological activity. It usually comes from animal and plant life. But it can also be formed by geological processes, such as interactions between rocks and water.

It was not the first time Curiosity has found methane gas in the Martian atmosphere.. About a year ago, NASA announced that Curiosity had discovered sharp seasonal increases in the gas. This time, NASA said the measured methane gas level was clearly larger than any others observed in the past. NASA officials even temporarily stopped Curiosity's other activities to investigate further.

However, Curiosity's team carried out a follow-up methane experiment that showed a sharp drop in levels of the gas. The rise and fall of the methane gas levels left NASA scientists with more questions than answers. The scientists are continuing to study possible causes for the sudden increase.

Curiosity does not have instruments that can exactly identify whether the source of the methane is biological or geological. One leading theory is that methane is being released from underground areas created by possible life forms that disappeared long ago. Even though Mars has no active volcanoes, scientists believe it is also possible that methane is being produced by reactions involving carbon materials and water.

The night sky has been an endless source of fascination since the start of human history. For example, the mysterious large-eyed, bronze statues of the ancient Shu Kingdom, discovered at the Chinese archeological site at Sanxingdui, were believed to have been able to look across great distances into the stars. In reality, humans can see very little of the night sky with the naked eye. And, for a long while, people were unable to understand what they could see. 【小题1】

Our power to investigate and thus understand space changed dramatically when the first telescope (望远镜) was angled at the night sky, increasing as it did the power of the human eye and enabling us to understand that the universe is far larger than was previously imaginable. The planets were seen to be worlds similar to our own, many of them even having their own moons.     

【小题2】 Some 300 years later, we learnt that the Milky Way itself was just one galaxy among billions of others, spread across the blackness of space like great islands of light and matter floating in a vast cosmic ocean.

Almost 400 years after the first Earth-based telescope was invented, the Hubble Space Telescope was launched into orbit, giving astronomers indeed all of us — the first breathtakingly beautiful images of our universe taken from beyond Earth. 【小题3】 It has also helped us to work out the age and nature of the universe, and discover the incredible fact that the universe is expanding at an ever-increasing speed.

【小题4】 Currently, China operates the world’s largest and most powerful radio telescope, the FAST telescope, completed in 2016. The 500-metre dish of the “Eye of Heaven”, as it is known, is being used in the search for dark matter. This vast dish also has the ability to explore regions of space billions of light years away, right at the edge of the visible universe.

Astronomers have examined the stars that a new space telescope might target, to prepare for one of the most advanced searches for life on other planets. They found out which star systems might be more suitable to hunt for potential life.

In the 2040s, NASA plans to launch the Habitable Worlds Observatory(HWO). Its big goal is to image about 25 Earth-like planets in the habitable zones of sun-like stars-where water and even life could exist. Before building the HWO, scientists are working on significant challenges it will face.

One of those is choosing stars within around 100 light years from Earth that the telescope might target. Caleb Harada at the University of California, Berkeley, and his team analyzed 164 potential stars to determine their characteristics. These stars could become some of the most studied stars ever.

Harada and his team discovered that 102 of the stars are binaries(双子星), which could make the search for life more complex. The HWO telescope will use a tool to block out the stars’ light to attempt to image planets in orbit and study the gases in their atmospheres. “If binaries are too close together, the light from the unblocked star will be so bright that it’ll cover up the planets and make them hard to see,” explains Bruce Macintosh from the University of California Observatories.

Out of all the stars, 33 have dust rings that could make it hard to see planets clearly. “This makes exploring harder,” says Harada. “Some stars also sometimes burst into bright flames, like our sun’s flares, which aren’t always deadly. But we need to check closely that they’re not too strong, because these can affect life and living conditions,” explains Harada.