字幕表 動画を再生する 英語字幕をプリント NASA's rovers on the surface of Mars are revealing answers to some of the biggest questions about our nearby planetary neighbor. And driving this rover – that is, on average, 225 million kilometers away from Earth – requires robust technology and years of development. And it's about to get even more advanced with Mars 2020. VANDI: Even though the rovers do so much, the computing power we have on board is actually fairly limited. The average phone a person carries has far more computation than we have onboard the rover. And the reason is because there's a lot of radiation, so we have to use computers that are radiation-hardened. Dr. Vandi Verma has worked for over eleven years developing and operating Mars rovers at NASA's Jet Propulsion Laboratory. VANDI: To send the commands to the rover, we send a fairly compacted set of instructions. When we uplink the sequence to the rover, everything goes through the Deep Space Network. And to get the data back, we transmit it to orbiters, which are actually just in Mars orbit. And then those orbiters transmit it through the Deep Space Network. In fact, we actually have programs on our phones so that whenever the data comes down, you get a little summary. We have a lot of different ways we parse the data, summarize it and depending on what happened, we may dig into a particular area more or less. While we're doing all this, the science team is having a discussion on what to do next. Given the distance between Mars and Earth, NASA can't joystick the rover's every move. So rover planners like Dr. Verma have to map the rover's entire day of sequenced movements perfectly. VANDI: The biggest concern is, 'is the rover going to be safe?' There's imprecision in the data, and in the positioning. So you have to take into account that, 'I am placing this delicate lens within proximity of this other rock. If it was off by five millimeters, is that a hazard? That's sort of what we look for, are those situations. It's a lot of fun. Over the last 20 years, each mission has built on its predecessor, enhancing the critical engineering and design of rovers like Sojourner, Spirit, Opportunity, and Curiosity. And Mars 2020 will be no exception. VANDI: With Opportunity, we were coming across sand a lot more on Mars. We had a situation where the rover was driving along, and by the encoders, as you measure, it's thinking it's covering all this distance and it kept on moving but it's just embedding itself deeper and deeper and deeper. Based on that, we developed the visual odometry technique, which allows us to use cameras to take an image, take another image, and if the rover hasn't moved we'd be able to see that the features have not moved between those images. For 2020, we wanted to be able to drive even more precisely, and we needed to do visual odometry even faster. So we now have a dedicated computer, so that it's so fast that we don't have to think about it. Now this allows scientists to get into more challenging terrain. Mars 2020 will also include a series of major firsts. VANDI: After we land, we're going to deploy this helicopter which is as large as the size of a softball. It'll fly for short durations and it's solar powered, and we'll be able to get data from it. So this is the first time we've had a helicopter on Mars, and that will be really exciting as well. And perhaps the most exciting step will be bringing extraterrestrial samples back to Earth. So what's really incredible with Mars 2020 is that we're going to collect a core this time of the sample. The rover will store the sample cores in tubes and deposit them at precise coordinates, known as sample cache depots. Detailed maps will be provided for future missions to retrieve them and return to Earth. VANDI: And once we get that sample on Earth, it's going to be quite incredible. And then they will actually be sent to labs all over the world and it'll probably be decades that they will be analyzing that. Mars exploration has come a really long way. We now know about seasons on Mars; we know how methane migrates. So there's so many ways in which the history of Mars and Earth are so intertwined. What is it that caused Mars to today be this arid environment, and how does that relate to Earth, which is teeming with life and this beautiful blue planet? And that has opened up a whole new area of science and understanding and allowed us to analyze these details very carefully. Humans are definitely someday going to be on Mars, and the rovers are making discoveries that will make that possible and make decisions on how we do that. This episode was presented by the U.S. Air Force. Learn more at airforce.com. For more episodes of Science in the Extremes, check out this one right here. Don't forget to subscribe, and come back to Seeker for more episodes. Thanks for watching!