【推荐1】    1     They create carbon dioxide and shade. They provide shelter to animals and insects. The wood they provide is used for buildings and other products we humans use and need.

Trees are so important that some people have made it their goal to protect them. We can call these people ‌“tree hugger”. It describes people who support the protection of forests. Today, the term ‌“tree hugger” describes a person who is an environmentalist.     2     For example, someone who wants to save a rare butterfly species or cut greenhouse gases could also be described as a tree hugger.

However, calling someone a ‌“tree hugger” is not always seen as a praise.     3     ‌“Tree hugger” described someone who was overly concerned about protecting trees, animals and other parts of the natural world.

Some tree huggers do go to extremes to protect trees. Take, for example, an American woman named Julia Lorraine Hill. For 738 days from December 10, 1997 and December 18, 1999, Hill lived in Luna, a Redwood tree in northern California’s Humboldt County. Luna is huge, measuring nearly 61 meters tall and about 12 meters across, which has stood in Humboldt County for more than 1,000 years.     4     So, Hill did what any extreme tree hugger would—she moved in! As the website explains, Hill’s main goal was ‌“to bring international attention to the importance of protecting and restoring natural resources.” So, we can safely call Hill a tree hugger.     5    

【推荐3】This year, why not think of Earth Day as being like New Year’s Day?     1     Make a plan to do things differently and do something for our mother Earth. Keep on doing one of these for a year and see how it affects your health and the world.

Send your kids out to play. Sign up for the 1,000 hours challenge, where families accumulate (积累) 1,000 hours of outdoor play in a year.     2    Your children will be happier, healthier, and more connected to nature.

Learn how to cook five easy main dishes well. By promoting your kitchen skills and developing some of your own recipes, you won’t be so much interested in take outs and all the related packaging waste.    3    

    4     Download the Poshmark app onto your phone or visit the ThredUp website before ordering new clothing or shoes online. There are so many companies that there’s a good chance that you’ll find exactly what you need. Visit Facebook Marketplace, local exchanging sites, and more to find what you need in your daily life.

Walk or bike, don’t drive.    5     It will require making time adjustments, but if you view that time as an investment in mental and physical health, it’s not so hard to schedule. If you can sell a car, you might be able to justify purchasing an e-bike, which makes low-carbon travel even more accessible and fun.

【推荐1】China welcomed three heroic astronauts home on April 16. The re-entry module (返回舱) carrying Zhai Zhigang, Wang Yaping and Ye Guangfu touched down safely at the designated Dongfeng Landing Site in Inner Mongolia autonomous region. This ended the Shenzhou XIII astronauts’ six-month space mission.

This return marks a major breakthrough for China’s efforts in space. Let’s look at some of the technical details of the mission.

Speed record

The mission set a new speed record. The Shenzhou XII return capsule revolved around the Earth 11 times over 24 hours, before returning on Sept 17, 2021. This time Shenzhou XIII shortened the time to about 9 hours, orbiting the Earth five times.

The Shenzhou XIII mission was simplified to only five orbits and was designed to return more efficiently, according to the Chinese Academy of Space Technology (CAST).

This approach required more precise control of the spacecraft and more accurate orbital calculations. This meant that when the spacecraft separated, it could quickly target the landing area, calculate the return path, and adjust its altitude, Wang Ya’nan, editor-in-chief of Beijing-based Aerospace Knowledge magazine, told the Global Times.

“Having the ability to adopt such a fast return method indicates that China’s return technology for manned missions is very mature and reliable,” Wang added.

Temperature control

Another challenge for astronauts returning to Earth is traveling through the atmosphere. After the re-entry capsule enters the atmosphere, there is fierce friction with the air. The surface temperature of the capsule can reach thousands of degrees.

To solve this problem, the researchers designed a heat-resistant coating on the surface of the Shenzhou XIII return capsule. They also laid a layer of ablative material (烧蚀材料) that sublimated (升华) and fell off when the temperature reached a certain level, taking a lot of heat with it, according to People’s Daily Online.

Landing

Landing upright is the ideal way to land, ensuring astronauts have the softest landing, Pang Zhihao, a spaceflight researcher in Beijing, told Science and Technology Daily.

【推荐3】Moon dust is the absolute worst. Not only does electrostatics (静电) cause it to stick to virtually everything, but it also has the consistency and feel of finely ground fiberglass. It was a genuine problem for the six Apollo crews who visited the moon’s surface — moon dust covered their suits, worked their way into engines and electronics, and even ruined a few of their extremely expensive spacesuits.

These are all serious issues to consider ahead of NASA’S planned return to the moon’s surface in 2025, but a team of college undergraduates at Washington State University just developed a solution to moon dust — spraying liquid nitrogen (氮) onto moon dust. The team developed a new spray that takes advantage of the Leidenfrost effect. Named after its discoverer, an 18^th-century German doctor Johann Gottlob Leidenfrost, it occurs when a liquid comes into close contact with a significantly hotter surface, causing it to quickly form a protective layer of vapor (蒸汽) that briefly keeps it from evaporating, such as when water forms into drops and runs across a very hot frying nan. The same principle works similarly in space. In this case, a liquid nitrogen spray (typically around -320℉) comes into contact with a surface’s relatively warmer lunar dust coating, causing the particles to turn into things like drops and float away on the nitrogen vapors.

To test their spray, the research team first dressed a Barbie doll wrapped with a material used to make spacesuits. They then sprayed it with liquid nitrogen in a normal atmospheric condition as well as the circumstances similar to outer space. Not only did the liquid nitrogen spray perform better in the latter circumstances, but also it only resulted in minimal damage to the spacesuit material. In past lunar missions, astronauts’ specialized brushes for the moon dust task often caused damage to spacesuits after a single use. In comparison, the liquid nitrogen spray took 75 uses before similar issues occurred.

Going forward, the team hopes to further research the complexity that makes the cleaning process so effective, as well as secure funding to construct testing rooms more closely resembling the lunar surface’s gravity. With any luck, maybe a can of their Moon-Dust-Gone will be aboard a future Artemis mission, ready to help astronauts avoid one of the lunar surface’s annoying things.