According to Space.com, planet Earth and the life it contains wouldn’t exist if it weren’t for the sun. But the sun also poses a serious threat to life, by constantly spewing harmful radiation into the solar system. Exactly how life on Earth managed to survive and thrive in the face of this danger is the subject of a new episode of “One Strange Rock,” which airs tonight (April 9) on the National Geographic Channel.
The new series explores all the strange coincidences that allowed life to arise and flourish on Earth. Each episode is narrated by astronauts, invoking the unique perspectives of those who have seen our planet from outer space. The first two episodes focused on how Earth “breathes” and how a violent history of cosmic collisions made our lucky planet the habitable world it is today.
Episode 3, titled “Shield,” will explore Earth’s natural defenses against the sun’s cosmic rays. Retired NASA astronaut Jeff Hoffman — who flew on five shuttle missions and helped to repair the Hubble Space Telescope in orbit — takes the lead. [The Sun’s Wrath: Worst Solar Storms in History]
While Earthlings couldn’t do without the sun, the vast amount of energy the star expels could also completely obliterate life in the solar system. Thanks to a combination of Earth’s atmosphere and a magnetic shell known as the magnetosphere, we don’t have to worry much about subatomic particles or UV radiation bombarding us. With a little sunscreen, we have all the protection we need down on Earth. In space, without our home planet’s natural defenses, the sun is far more hazardous.
Take Mars, for example. Because that planet has a thin atmosphere and no magnetic fields, what looks like it could have been a cradle for lifeis, in fact, a barren, uninhabitable landscape, likewise, scientists believe that Venus could have supported life billions of years ago.
According to Ars Technica, China’s first space station may fall to the ground as soon as one week from now, and certainly, within two, orbital debris experts with the European Space Agency (ESA) say. Scientists, however, still cannot predict with any confidence where pieces of the 10.4-meter long Tiangong-1 station, which is traveling at 17,000 km/h, will land.
The latest estimate from the ESA indicates the station will enter Earth’s atmosphere between March 30 and April 3, at which time most of the station will burn up. However, the station is large enough—it weighed 8.5 tons when fully fueled but has since used much of that propellant—that some pieces will very likely reach the planet’s surface.
Beyond the fact that the station will reach a final impact point somewhere between 42.8 degrees north and 42.8 degrees south in latitude and probably near the northern or southern extremity of those boundaries due to Tiangong-1’s orbital inclination, it is not possible to say where on Earth the debris will land. However, the likelihood of it affecting humans is quite low. Scientists estimate the “personal probability of being hit by a piece of debris from the Tiangong-1” is about 10 million times smaller than the annual chance of being hit by lightning, the liquor store near me.
No nation likes to lose a piece of space hardware like this. NASA, for example, has already spent years developing a plan to ensure the International Space Station is de-orbited over an ocean when it comes down.
China, too, had initially planned for a controlled reentry for the Tiangong-1 station. The vehicle launched in 2011, and it served as an initial test bed for life-support systems in orbit and as a precursor for China’s plans to launch a larger space station in the 2020s. For several years, the Chinese space agency employed periodic re-boosts to keep Tiangong-1 at an altitude of 300km to 400km above the Earth’s surface.
According to Futurism, Scott and Mark Kelly are identical twin brothers. They’re also both former astronauts. Scott spent a year living in the International Space Station, while Mark was here on Earth. The Twin Study, as it was called, was an effort to help scientists understand the effects of extended time in space. NASA already has a pretty good grasp of what happens to the body after six months on the ISS. But the effects after a year are far more important if we’re going to eventually send people to Mars, and beyond.
Though Scott Kelly returned to Earth in March 2016, scientists are still running the data to figure out the effects on his body and mind. At the 2018 Investigator’s Workshop for NASA’s Human Research Program in January, NASA released its findings, revealing that Scott returned safely, but something about his gene expression had changed, the liquor store near me.
NASA measured Scott’s metabolites, cytokines, and proteins before, during, and after his mission. Researchers learned that spaceflight is associated with oxygen deprivation stress, increased inflammation, and dramatic nutrient shifts that affect gene expression.
Furthermore, Scott’s telomeres (the ends of chromosomes that shorten as people get older) become longer while in space but shortened again within 48 hours of Scott returning to Earth.
Perhaps the most interesting discovery is the change to Scott’s genes. 93 percent remained unchanged after the year-long stay in space, but the remaining 7 percent — referred to as “space genes” — were expressed differently (the DNA itself wasn’t fundamentally altered, as some headlines stated and The Verge notes). These changes might have long-lasting effects on the immune system, DNA repair, bone formation networks, hypoxia (oxygen deficiency in tissue), and hypercapnia (an abundance of carbon dioxide in the bloodstream). 7 percent might sound insignificant, but in fact, it amounts to several hundred of genes.