字幕列表 影片播放 列印英文字幕 Mars is our next-door neighbor, and yet... we almost never visit. We sent the InSight lander in 2018, an orbiter and lander combo in 2016, and two orbiters before that in 2013. Basically one or two missions every couple of years or so. But in July of 2020, humans are launching four separate missions to Mars. What is going on up there? Why all at once? Is there some incredible black Friday sale going on or something? Sadly, no – no amazing TV deals are to be had on Mars. But the July 2020 launch window does offer great savings… on rocket fuel. The reason all these missions are launching then is because that is the ideal time to get a craft to Mars while using the least amount of fuel. But it’s not when the two planets are at their closest, as you might expect. The most efficient way to send a spacecraft to Mars is using something called a Hohmann Transfer Orbit. This orbit is elliptical, and uses the sun as one focal point. The spacecraft’s launch is at the closest point to the sun, or perihelion, and it crosses Mars’ path at its farthest point from the sun, or aphelion. It is very important, I cannot stress this enough, that Mars is actually there when the spacecraft arrives. No duh, right? But for that to happen the spacecraft has to be launched at just the right time. The time it takes a spacecraft to travel from perihelion to its aphelion in Mars’ orbit is about 259 days. During that time Mars will move about 136 degrees, since Mars is farther from the sun than Earth and takes longer to move the same angular distance. So in order to sync up the 180 degrees the spacecraft will travel while Mars moves 136 degrees, the spacecraft needs to launch when Mars has a 44 degree head start. This happens for a few weeks once every 26 months, and the next time it will happen is, you guessed it, mid-July of 2020. And this time around a lot of space agencies are geared up for launch. First up, with a scheduled launch window of July 17th to August 5th is another Mars Rover from NASA, named Perseverance. The latest car-sized bot is landing with the goal of searching for signs of microbial life, and determining if Mars’ environment was more hospitable to it in the past. It will also collect and cache samples of rock and regolith, and test oxygen production in the atmosphere. The rover will also touch down with an autonomous helicopter on board. That’s right: it’s bringing a drone to Mars, though this one is specially made for the thin Martian atmosphere. It will carry no scientific instruments; its only goal is to test if this is an awesome or dumb idea. Next on the docket is a joint mission from the European Space Agency and Russia’s Roscosmos. The mission’s rover, provided by ESA, is named Rosalind Franklin, after the pioneering English chemist and x-ray crystallographer whose work was instrumental in discovery of the structure of DNA. She basically took a picture of the double helix. Franklin died unrecognized for her contribution in 1958. It’s good to see her get a nod from ESA more than 60 years later. Rosalind Franklin (the rover) will explore what scientists think may have been an ancient ocean. Like the NASA mission, the rover will search for signs of life past and present. It will use a camera attached to a drill to study the soil it brings to the surface and I can’t think of a much better tribute to Rosalind Franklin than a camera searching for signs of life on another world. Finally, the remaining two missions are important milestones for two different space agencies. The United Arab Emirates will launch its Hope orbiter sometime in July, with the goal of studying Mars’ fading atmosphere. If it goes as planned, the UAE will claim the title as the first Arab nation to send a spacecraft to Mars. China is also planning to send an orbiter and rover combo named HX-1 to Mars. This will be their second attempt, after their first Mars orbiter was stranded in Earth's orbit and then destroyed by our atmosphere back in 2012. With this stellar lineup of missions, July 2020 will be an exciting time for Mars exploration. Hopefully all goes as planned, and 259 days later we’ll have a new squad circling the red planet and kicking up regolith. Because if not, we have to wait 26 months for another shot. And you thought waiting a year between TV show seasons was hard. ESA and Roscosmos’s mission is launching in 2020 after missing its original planned window in 2018 due to technical setbacks. The 26-month wait has helped make this summer one of busiest seasons of Mars launches yet. Thanks for watching. If you want more Mars videos, check out this one I did on why the Mole on NASA’s InSight lander can’t seem to burrow beneath Mars’ surface. Be sure subscribe, and I’ll see you next time on Seeker.