00:00Mars is the Earth's space cousin. It's the fourth planet in our solar system, about half the size of the Earth.
00:07It also has two small moon buddies, Phobos and Deimos. These moons are shaped like potatoes.
00:13Phobos is the drama king, moving closer to Mars and planning a crash landing in about 50 million years.
00:20Deimos is much calmer though, hanging out farther away from Mars.
00:25Mars got a cool nickname, the Red Planet, thanks to its rusty red surface.
00:30This color was so bright that it was spotted by astronomers many years ago.
00:35Even you can sometimes see it in the sky with the naked eye, a small scarlet dot.
00:40And maybe it has hot vibes, but in reality, Mars is a very cold desert.
00:45The temperatures there can drop as low as minus 240 degrees Fahrenheit.
00:50But was Mars always nothing more than a rusty-looking desert? Actually, no.
00:55Scientists believe that perhaps many years ago, this planet was similar to ours.
01:01Meet Curiosity, the detective rover made by NASA's Jet Propulsion Laboratory.
01:07Scientists want to know all about the Martian weather, landscape, and other stuff like that.
01:12Curiosity is a pretty heavy car-sized robot. It weighs about 1,985 pounds.
01:19It embarked on its journey on November 26, 2011.
01:24The rover pulled off a landing on Mars on August 6, 2012.
01:29Originally, Curiosity's mission was supposed to last for two years, but it's still going strong.
01:35Curiosity is basically a space lab on wheels.
01:39It's packed with cameras, spectrometers, radiation detectors, and sensors to sniff out the Martian environment.
01:46As Curiosity roams around, it rewinds Mars' history.
01:51And during its mission, the rover discovered something incredible.
01:55Signs of lakes and rivers from long ago.
01:59You see, Curiosity's favorite spot to play around is Gale Crater.
02:03It's a prehistoric Martian oasis where water might have hung out.
02:07There's this huge mountain in the middle called Mount Sharp.
02:11This place is taller than ten Eiffel Towers stacked on top of each other.
02:15And it's got layers of rocks that hold Mars' ancient secrets.
02:19Recently, scientists spotted something great when studying Curiosity's data.
02:24Mud tracks! What's so surprising about that?
02:28Well, these aren't just any old tracks. They're like messages from the past.
02:33They mean that the Martian ground used to get wet and then dry out again.
02:38The mud on the ground would shrink and crack during the drying phases, making these T-shaped junctions.
02:44Moreover, it seems like the ground on Mars went through several wet-dry cycles.
02:49It happened maybe up to ten times. This made the junctions turn into Y-shaped cracks.
02:55When a bunch of Y-shaped cracks got together, they made a super cool pattern.
02:59Something like a patchwork of hexagons.
03:02It looks just like honeycombs or even a dragon's skin.
03:06Each of these hexagons are the size of candy.
03:10Similar cycles have happened on Earth, and they're linked to the birth of life.
03:15When water dries up, it leaves behind concentrated stuff that's great for chemical reactions.
03:20And these reactions might be the same ones that kick-start life.
03:24These hexagons have been hanging around for a really, really long time. Billions of years.
03:29That means that Mars once had a climate kind of like Earth's, and maybe even life.
03:36In fact, the Red Planet even has some signs of water right now, in the form of hidden ice at the poles.
03:43Mars has the North and South Poles, and just like with the Earth, they're Red Planet's ice caps.
03:49Picture the North Cap as a big icy pancake about 620 miles wide.
03:54The South Cap is a bit smaller, about 220 miles wide.
03:59But it's got a thicker ice layer, almost like a snowball with a strong shell.
04:04When it's winter at the poles, it's an incredibly long nighttime.
04:08No sunlight, just chilly darkness.
04:11During that time, around 30% of the air turns into frozen CO2.
04:16It's dry ice, the same stuff that's often used in horror movies.
04:20But when the poles wake up to sunlight, the dry ice turns back into gas.
04:25All this freezing and thawing makes clouds and frost, just like on Earth.
04:30One time, a rover named Opportunity even caught some clouds made of water ice.
04:36But it doesn't necessarily mean Mars was once thriving just like the Earth.
04:41Life needs more than just wet-dry cycles to pop up.
04:44It needs the right atmosphere and other special ingredients.
04:48We're not sure if Mars had all of those.
04:50And even if it did, there's no guarantee that life actually happened.
04:55But this raises another very important question.
04:58Has Mars ever hosted tiny living creatures?
05:02Curiosity isn't the only robot that tries to find the answer to that.
05:06There's also a rover called Perseverance.
05:09It's trying to find clues about Martian life.
05:12It's digging into an old Martian crater once filled with water.
05:16And like a space archaeologist, Perseverance is searching for fossilized signs of ancient critters.
05:23And here's the funny thing.
05:25Some scientists think that we've stumbled upon it almost half a century ago.
05:29The only problem is we might have accidentally destroyed it.
05:33It happened even before Curiosity started rolling around Mars.
05:37Back in the 1980s, two cool NASA's landers, Viking 1 and Viking 2, made a pit stop on the Red Planet.
05:45These landers took a selfie.
05:47And then they also did some funky experiments on the Martian soil.
05:51All in the name of finding signs of life.
05:54What they found is some weird organic stuff called perchlorate.
05:58It's a compound that we use in fireworks or rocket fuel.
06:02But most results didn't seem that promising.
06:04They even mixed up some soil with water and nutrients, hoping that if there were Martian microbes,
06:09they'd snack on the goodies and return radioactive gas as a result.
06:13But unfortunately, that didn't happen.
06:17Now, here's the problem.
06:19Some scientists think that maybe the water they added back then actually destroyed those tiny Martian critters.
06:26Poor microbes were just hanging out and suddenly got soaked by a bunch of weird liquid.
06:32Something like this wouldn't be very pleasant for the Earth microbes.
06:35They live inside rocks, and they're sucking water from the air.
06:39Pouring water on them would result in a total disaster.
06:42So, of course, giving them nutrients after that wouldn't do anything.
06:46If you've just barely survived a water bath, you're probably not in the mood for a feast.
06:52Perhaps these Martian buddies might have something called hydrogen peroxide in their cells.
06:57It helps them live in an extreme environment.
07:00If that's true, it could explain all the results from the experiments.
07:04You see, the instruments heated up the samples.
07:07So, if there was hydrogen peroxide, it would have gone boom,
07:11wiping off the little guys and turning their cozy homes instantly.
07:15Imagine how ridiculous it would be if it turns out that we accidentally destroyed the only signs of life on Mars.
07:21Ideally, we need a new mission to Mars to test this theory.
07:25Let's hope it's not true.
07:27In any case, the journey isn't over.
07:30There are more missions planned for Mars, and humans might even visit this planet someday.
07:35The next mission is the Mars Sample Return.
07:38It's a super cool teamwork project between NASA and ESA.
07:43They're teaming up to bring back souvenirs from Mars, collected by NASA's trusty Mars Perseverance rover.
07:50There's going to be a whole bunch of spaceships.
07:53They'll work together to bring these precious Mars samples back.
07:57The samples are planned to arrive on Earth in the early to mid-2030s.
08:02And the fun doesn't stop at Mars.
08:05Our Mars missions are a warm-up for an even bigger adventure, exploring icy moons around Saturn and Jupiter.
08:12These moons have hidden oceans beneath their icy surfaces, and who knows what kinds of space secrets they're hiding.
08:19But whether it's Mars, icy moons, or beyond, our quest to find extraterrestrial life continues.
08:25In addition, we are slowly starting to find more and more organic materials on Mars.
08:31And maybe one day, we'll finally find some microbes in our solar system.
08:35Let's hope for it, and stay tuned.
08:43That's it for today.
08:44So, hey, if you pacified your curiosity, then give the video a like and share it with your friends.
08:49Or if you want more, just click on these videos and stay on the Bright Side.
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