Talk Description to Me

Episode 38 - Landing on Mars

February 18, 2021 Christine Malec and JJ Hunt Season 2 Episode 38
Talk Description to Me
Episode 38 - Landing on Mars
Chapters
2:07
The Perseverance Rover
11:03
The Ingenuity Helicopter
14:48
The Martian Landscape
21:50
Entry, Descent, and Landing
Talk Description to Me
Episode 38 - Landing on Mars
Feb 18, 2021 Season 2 Episode 38
Christine Malec and JJ Hunt

It's all about Mars and the Perseverance Rover on Talk Description to Me this week. To enhance the commentary and resources that come directly from NASA, Christine and JJ describe the look of mission hardware, discuss the compelling visuals of the Martian landscape and landing site, and break down NASA’s cinematic representation of a perfect entry, descent, and landing.

For more information, including details on the rover's onboard microphones, check out the mission's official website: https://mars.nasa.gov/mars2020/


Support the show (https://www.patreon.com/TalkDescriptionToMe)

Show Notes Transcript Chapter Markers

It's all about Mars and the Perseverance Rover on Talk Description to Me this week. To enhance the commentary and resources that come directly from NASA, Christine and JJ describe the look of mission hardware, discuss the compelling visuals of the Martian landscape and landing site, and break down NASA’s cinematic representation of a perfect entry, descent, and landing.

For more information, including details on the rover's onboard microphones, check out the mission's official website: https://mars.nasa.gov/mars2020/


Support the show (https://www.patreon.com/TalkDescriptionToMe)

JJ Hunt:

Talk description to me with Christine Malec and JJ Hunt.

Christine Malec:

Hi, I'm Christine Malec.

JJ Hunt:

And I'm JJ Hunt. This is talk description Me with the visuals of current events and the world around us get hashed-out in description rich conversations.

Christine Malec:

If you like me, are a space geek, February 18th 2021, big historic day, the NASA Mars Perseverance rover is going to be landing. And there's lots of coverage and information and excitement and enthusiasm about this. And NASA has its own website crammed full of resources. And some of them are accessible, some of them are not. But NASA definitely has its own context for covering the event. And so what we want to do today is not to try to reproduce that or even to talk alongside that what we want to do is give the background so that all of those things will make a lot more sense, after you've listened to, to our episode today if you're someone who's blind or low vision. And so we're going to start by talking about what some of the things involve look like. And then we're going to use some of NASA's resources to walk through the process. And so, JJ, why don't we start with the vehicle itself? What can you tell us about what that looks like?

JJ Hunt:

So the Perseverance rover is based on the Curiosity Rover's configuration. So if you're familiar with curiosity, it's quite similar. This rover is bigger. So perseverance is about 10 feet long, not including the arm, about nine feet wide and about seven feet tall. So it's the physical size of a big car, but it's relatively light, only 2260 pounds. So it's actually about the weight of a compact car. So it's relatively light for its size. And NASA's website has this amazing 3d image of the rover so you can flip it and turn it and zoom in and zoom out. So I was able to kind of really get into the nooks and crannies to to explore this thing. It's a pretty cool little vehicle. So the rover has a boxy rectangular body. I've seen it painted white, but some images seem to show it as an unpainted aluminum body. And it's this body is like a platform. So picture, like a family sized cereal box, lying on its front, right? So it's wider than it is tall. It's it's boxy and like a platform. And it's of course, covered with doodads and doohickeys, which are, of course, the official NASA terms for all the technology.

Christine Malec:

Stop overwhelming us with this technical language. It's very daunting. We've already lost half the listeners already, because you've just over spoken.

JJ Hunt:

Ha ha! Oh my god, I can't get on board with the doohickeys.

Christine Malec:

Ha ha.

JJ Hunt:

So it's like a platform for all of the tech. And then there's another box. Kind of a shorter, more square box that's sticking up off of the back of the main platform, the main body at a 45 degree angle. This is the power source. And this box is open on the top and bottom. And what it reveals is there's a cylindrical fan inside. So this is the power source at the back at the front of the rover. So this would be the front right like the passenger side for an American or Canadian car. There's a mast and it sticks straight up from the top of the body. And on top of the mast is a series of cameras in a box that looks something like a shoe box with the wide side facing forwards at the front. So right on say this was the grille of a car, the front of the car or the front of the of the body. There's a folded arm, and this arm can kind of pull in and bend and tuck right in again. The front of the rover. And on the the what would be the hand, the there is a drill on the end of it. And that drill when the arm is folded in, it sits on what would be the driver's side when it's not extended. There are three wheels on each side of the vehicle. It's an ingenious, intriguing balancing suspension system. So three wheels on each side. And you might expect each wheel to be connected to the body of the vehicle in the way that most cars are like that, right, you've got two wheels at the front, two wheels at the back on a car, and they are connected to the body. But that's not the way these wheels are connected here. The three wheels on one side are each connected to each other using suspension tubes that are flexible and have joints in them so that they each wheel can move independently. So those connected units of three are only attached to the body with one joint. So on each side, three wheels on each side, those suspension systems are connected on one joint per side. And they call this a rocker bogie suspension system because it can tip back and forth like a teeter totter, as the wheels are moving it along. Because it's only connected at one pivot point. The tires themselves, they look like they've got thin rubber treads around like barrel shaped wheels. So very wide wheels with open spokes. But in fact, there's no rubber involved. The wheels are a thin machined aluminum that are painted black, and they're only as thick as seven sheets of paper. And when the aluminum is that thin, it becomes as flexible as rubber. So it's got a bit of a spring to it. But it's much more durable than rubber would be. And these this the rover is six wheel drive. So all six wheels can spin independently. And with that means you can spin on all four corners, you can literally spin on the spot. So let's break down some of the specifics that we just talked about. So like the arm, for example, the arm at the front of the vehicle, it can extend up to about seven feet. And it has a shoulder joint near the near the vehicle. It's got an elbow joint in the middle, and a wrist joint near the tools at the at the hand. And the hand is known as either the hand or the turret. And my understanding is that NASA actually refers to these as the shoulder joint, the elbow joint and the wrist joint. And what that configuration does, as you know your arm can do, you can do all kinds of things you can reach up, you can go to the side, you can twist and turn. So it's a very maneuverable series of joints. And then the device that's on that that's the hand of the turret has sensors, it has cameras, there's a drill here looks a bit like a if you're into tools, it's like a router. It's got a casing and there's a drill in the middle it can switch drill bits and then drill into the ground and get core samples. A major part of this entire mission is the ability to get core samples. Then there's the mast that we talked about. The mast elevates the camera system to provide a human scale perspective. So it's about seven feet tall. It also interestingly gives the rover a little bit of a humanoid look because of this boxy head. There's a single lens to one side, a big large lens. That's a laser micro imager, and it can identify chemical composition of rock and soil from a distance. And then below that, there are two side by side lenses that are smaller, and they've got boxy black frames. So it really looks like thick rimmed eyeglasses. These are the mastcam Z's or the mastcam zeds. And these two cameras are zoomable panoramic cameras that can take 3d images. So the zoom on this is apparently incredible. It can spot something as the size of a house fly from 350 feet away.

Christine Malec:

Tee hee!

JJ Hunt:

So that's the length of a soccer field. And it can create 3d images, panoramic images, very, very cool. And then the way this thing moves, so the way the rover moves, it's very, very slow. Like it crawls along at something like a few centimeters per second. And the suspension setup means that the tires can roll over rocks or dip into small holes independently and keep the main body level. So if you want to bit of help kind of conjuring that movement, just take your arms, put them at your sides with bent elbows, forearms parallel with the floor. So kind of like you're sitting in a in an arm chair and your arms are resting on the arms of an arm chair. And now very gently, quite calmly, start to move your arms up and down a little bit. You bend your wrists, bend your elbows, shrug your shoulders, and they don't have to be moving together, they can move independently. So each arm each joint very slowly rolling up and down, moving independently, but your body in the middle remains stable. And that's kind of how the rover looks when it's moving. With these slight rolls up and down as the tires, each individual tire rolls over a rock or dips into a hole in the body in the middle is remaining stable. That's how this rover looks as it's slowly moving along.

Christine Malec:

So that's just the outside. So there's other things inside too!

JJ Hunt:

Yeah, so tucked away in this rover is a helicopter; Ingenuity. The name of it is the Ingenuity helicopter. This is the first aircraft on Mars. And it's little, it's smaller. It's a little drone, basically. I don't know exactly how it gets unpacked, I haven't seen any images of how it gets unpacked. But they've got test footage, and they've got animations on their website, NASA shows the look of it once it's assembled and ready to go. So the needs for this helicopter, in order to get a helicopter moving on Mars, you need a very light vehicle and rotors that spin very, very, very fast. So the rotors on this helicopter on ingenuity, they spin at like 2 to 3000 revolutions per minute. Most helicopters on Earth, their main rotor spins at about 450 to 500 revolutions per minute. So it's a very fast.

Christine Malec:

Wow!

JJ Hunt:

And the vehicle has to be fully autonomous during its flight. So all of the computer equipment that is on board has to be really light, and it's got to be able to generate a lot of power. And it has to be smart, it has to be able to fly, you know, on its own. And the plan is to fly this helicopter at about three to five meters high, a three to five meters off the surface and travel horizontally at only a few meters per second. Maybe they'll go as far as 50 to 70 meters. If that goes well, maybe they'll they'll you know, they'll go further and then come back. It's really amazing, I think mostly they're going to be taking some pictures and testing the the technology. But if it goes well the the missions for this type of helicopter will be expanded. So the look of the helicopter, of ingenuity; The body really looks like a box made of tin foil. Just a very simple box made of tin foil. Rising up from that box in the center is a mast. And it has two stacked horizontal propellers. And each blade is a twin blade, meaning the mast is in the center and there's one blade on one side and one blade on the other. And there are two of those one on top of the other and they spin in opposite directions. And then above the propellers on the top of the mast is what looks like a flat solar panel. And there's a little short wire antenna that sticks up from that solar panel. It's a you know, just very straight stiff wire and there are a couple little zigzags in it. I'm sure those zigzags have some kind of function, but for me, it just adds personality. It's really cute. Heh heh.

Christine Malec:

Ha ha ha!

JJ Hunt:

So a little antenna coming up the top. The helicopter stands on four legs. And these four legs extend out from the top corners of the tin foil box at about a 45 degree angle. And they look a bit like golf clubs with the heads as the feet that are standing on the ground. And then they the shafts come back up toward toward this tin foil box and the spread of the feet and the length of the propeller blades. They're very similar there you know that that that's more or less the footprint that it's taking up is the same as the space that's required for the rotors to spin around. And that's the helicopter. It's like a little drone. It's really cool.

Christine Malec:

If you're a science fiction fan, you've probably read books set on Mars and I actually just did a reread of the Martian by Andy Weir. And so I feel like I was just there. I totally recommend it, amazing book. But I feel like it would be really nice to talk about the landscape or the view of the landing site. Can we do that?

JJ Hunt:

Yeah, so there's some really interesting images coming in of Mars right now. Mars is the hotspot right now. There are two or three other crafts that are orbiting Mars right now sending back amazing pictures. So the images of Mars itself have never been better, they've never been clearer. So Mars really does look red. Now not a solid red, right? I've got a couple of images here that more or less fill the screen of my laptop. If this was an object sitting in your hand, it would be somewhere between the size of a grapefruit and the size of a cantaloupe. So at that distance, at that perspective, Mars is reddish in color, but like a coppery color of red, like a brick red. And even from this distance, it looks dusty, there's a dull quality to the color. And it's mottled. So it's not a solid ball of uniform color. It is mottled; some places are darker, some places are lighter. And it looks kinda like a bowling ball! With something like the planet Earth, which is of course, that's what everything is compared to; Earth, with us being Earthlings and all! We've got continents, we've got water, we've got cloud, we've got deserts, we've got forests. There's all sorts of color variation. There's all sorts of land shape variation. Not as much with Mars, it's uniformly desert, all surfaces. There are canyons, there are planetary scars, there are there are rings (which are craters), there are volcanoes, there are cracks and rents in the surface. And some of those areas are quite dark. But it's still all desert. It's all this dusty color of coppery red. And then when you get closer to the landing site, the landing site is Jezero crater. And this is a crater that once held a lake. That's why they're going there. And I've seen some concept art [artist's interpretatins] of the lake as well as some satellite images. And in the concept art [artist's interpretations] they show this this crater filled with water, it's a lake that is hemmed in by the raised lip of the crater. And there are two winding rivers or streams that are connected to the main crater toward the distant like there, there are marshy areas or smaller bodies of water at the far ends of these winding rivers or streams that lead to and away from the main lake. So there's an inflow channel, at we'll call it 12 o'clock. And then there's an outflow channel at four o'clock. And you can see that both in the concept art - the artist's interpretation. As well as in satellite images, you can still see the dry channels that would be coming in at 12 o'clock and going out at four o'clock. And there's a Delta deposit at the mouth of the inflow channel.

Christine Malec:

Gasp!

JJ Hunt:

So this is a land form where sediment has been deposited by moving water as it arrives at this larger body of water. And this is the place to live if you're a micro organism. That's why Jezero crater is the place where they want to land because they've got access to this delta.

Christine Malec:

Oh my god, you got me with the delta. So when you're looking at the image that is not the the artist's conception but the actual image. Does your eye see Lake, River, Delta?

JJ Hunt:

Yeah, absolutely. Especially once you know what's there. If you see this image, and there's a caption at the bottom that tells you, that gives you some scientific information, informs you that this is a picture of a dry lake bed with an inflow and outflow it's clear as day. You can see the channel and you can see where there would have been a marshy area, and then when you zoom in closer you can see this delta deposit. They highlighted it in some of their images, but even without highlighting it, you can see that there's something there. That this deposit is different. The texture appears different, the topography of the Delta appears different than the rest of the inside of this crater which is relatively flat and smooth.

Christine Malec:

I have goosebumps! So I know that I'm a bit more like excitable about this than you. But does it affect you to look at that? Because I know you're not a big science fiction or space geek. But when you look at it, you see that it was land, do you see that it used to be something else it does that have an emotional impact on you? Or is it just scientifically interesting?

JJ Hunt:

For me, it definitely does. When you you know, when you look at the images like some of the images I first described of the planet, and I say there are rents and there are cracks, and there are creases, and there are these pock marks on it. You know, that's interesting. When you take a moment, and you say yeah, but that crack, that was from an earthquake! Oh, earthquakes, I know those! We have those. That's real, that's tangible. And that winding line that's a little bit pale, that looks like a thin scar running through a desert area. Oh, wait a minute; that's a that's a dry riverbed, or maybe it's a canyon, depending on how big it is. Oh, wait a minute, we have those on earth! And so suddenly, when I when I make those visuals real, when I compare them to what I know, thaings that are tangible, that are terrestrial, to me, it tells a story of a place that has changed, that has evolved over time, that has become this red ball in the sky that is a place that science fiction writers will turn that into a home. But it's the fact that it's real, tangible, it has changed. What is the history?

Christine Malec:

Yup.

JJ Hunt:

Every one of these marks has a history to it. What is the history of all of that? That's what gets me.

Christine Malec:

NASA prepared a video of the so-called seven minutes of terror! We thought we would talk about it at our leisure. So NASA, again, obviously has their own ways of covering this, and again, our intent is to give give some background and filler that as a non sighted person you wouldn't have. So we thought we would walk through the NASA construct of the seven minutes of terror. So lay it on us, JJ.

JJ Hunt:

Yeah. So what what they did was they they condensed it into three minutes; a three minute computer animated video that showed the planned landing for perseverance. And so this is a very cinematic take on this landing. They change camera angles, so to speak, they give different perspectives from the spacecraft and from the ground. And it's very dramatic. This is the landing as it would be seen if you had a professional film crew that had cameras floating in space and on the ground. This is what they would hopefully film as the landing craft was coming on. So I'm just gonna, I'll give kind of a summary description. I think this is the clearest visual that we're likely to get of this landing. So there are five key components of the entry descent and landing phase. There's the cruise stage, the back shell, the descent stage, the perseverance rover, and then the heat shield. And now the two stages, the cruise stage and the descent stage, the stages can be a little confusing, because the word "stage" I think, can mean both the phase but it's also the physical stage, the platform that is enabling this moment, right? So as the cruise configuration, which is what it's in right now, as the cruise configuration approaches Mars, the spacecraft resembles a squat spinning top with a rounded tip and a capped ring on top. The capped ring that's on the top, that's the cruise stage. It's got a flat top covered in solar panels, and then the underside (which is protected by the ring) is packed with electronics and what looks like wires inside rigid copper pipes. That's the underside of the cruise stage. And as the spacecraft approaches Mars it is released; separated. So the spinning top continues the descent on its own, and the cruise stage fades away. At this point, the outside of the craft is really just two components, the back shell and the heat shield. And together that's known as the aero shell. And again, it looks more or less like a spinning top with a with a smooth, pointed tip. So that smooth tip, the rounded point, the rounded tip, that's the heat shield. It's gold in color and it kind of looks a bit like Captain America's shield, but it's got a little bit more of a conical shape. And then the back shell behind it is also conical, but it's a little bit taller. Okay, that's the aero shell. The heat shield cuts through the atmosphere, so the Areoshell goes toward the planet heat shield first. And as it cuts through the atmosphere, small bursts of [what looks like] steam begin to puff out of the back shell, these are little jets that are helping to maintain the course. So they go PFFFT PFFFT! And that'll help steer and keep the heat shield pointed into the atmosphere. In the NASA animated video you get views from the surface of Mars as this streak of orange flame, like a comet, cuts across the dusty yellow sky that's above this desert planet. There are distant mountains in the background and you see what looks like a streaking comet. That's, that's the aero shell, that's this spacecraft coming in. At this point, we then cut back to of a close up of of the aero shell. And what looks like white hot flames are whipping past the aero shell. It looks like they're emanating from the rounded tip of the heat shield. And of course what this is, is the heat shield dissipating the energy that's caused by the friction of the spacecraft cutting through the atmosphere. Then the video gives us a little glimpse inside this shell that's around the important stuff. This is where the rover is. And inside the rover is the helicopter. So we get just a little glimpse inside, at this tucked-in rover. The wheels are kind of tucked up and folded up. And it's rumbling as the spacecarft goes through the atmosphere. And as we get closer to the planet, we pass few, just a very few wispy clouds. And then the topography of the planet's surface becomes clear. And we see there's a crater ring in the distance in front of us. And we're getting closer and closer to the surface of Mars. Now, there's a nub at the top of the back shield. At the top of this conical back shield, and from that nub a parachute on a very long cable suddenly ejected. It shoots up and it opens up. The chute opens and immediately the speed slows dramatically. This chute that opens up is round. It's mostly white, there's orange trim, it looks kind of like a knit cap like a toque or a beanie. And we get an overhead view of this tiny white dot, this parachute, dangling a cord and the rest of the back shield. That's hanging down from it, zipping across the surface of this sandy planet. That's from this overhead view. And then the heat shield separates, it drops away toward the surface. And inside, you now have the exposed rover. So the rover that's still inside the back shell is exposed to the air. And apparently at this point, the rover is going to start taking pictures. It's gonna start taking images of the surface. And the rover itself will use those pictures to determine where it's safe to land. This will allow the vehicle to land near interesting things but not on top of dangerous things. So moments after the heat shield drops away the images have been taken by the rover, the descent stage inside the back shield drops down. And the descent stage is both a name for this stage when it's descending further, and the stage as a literal platform. And now everything is exposed. There's no casing on anything. You have the rover tucked into the descent stage, and in this configuration, it's kind of Puck shaped. The descent stage looks a little bit like a rounded robotic turtle shell with four landing jets instead of legs, and then the rover is tucked underneath it. So one way to imagine this is imagine getting on your hands and knees to protect a child with your body. So there's a child kind of underneath you and you're on your hands and knees. That's kind of what this looks like, with your arms as these landing jets. And the back, your back, is the back of the descent stage. The jets quickly fire up, they burst with flames, and this enables the stage to gain control. With these four jets, flames shooting out from the corners, that's how the descent stage maintains control. Now, I've been watching the Mandalorian a lot lately, I've been binging the Mandalorian.

Christine Malec:

Ohhh.

JJ Hunt:

And I have to say, this descent stage really reminds me of the Mandalorian, it's a little bit near future tech. The back of the stage is open so you can see the framework, you can see the electronics, it's all exposed, there's no cover on it. And the landing jets are just spewing fire. It's very mechanical, very elemental. It's not like laser beams and, you know, pulse engines. It's fire, it is framework, there's something very tangible about it. And reminds me of what the Mandalorian and early Star Wars stuff does very well, which is make the make the tech, the androids, the ships look real. Sometimes dirty and sometimes broken, you know, this is very real, tangible looking equipment. So once the descent is controlled, the descent stage steers a bit, it adjusts course by you know, firing one jet hotter than the other. And the flat dusty surface of Mars starts getting closer and closer as the descent stage continues its descent. And when it's about 20 meters off the ground, the rover drops away from the descent stage, lowered on cables. They call this the sky crane. So from about 20 meters off the ground, the rover drops down on a cable, and it is slowly lowered to the ground. It unfolds, the rover unfolds a little bit so that the wheels and suspension system are all in order, so it's in like proper driving configuration. The descent stage drops closer to the surface until the vehicle touches the ground. It actually just lands, it settles down on its wheels. And once it's done, once it's landed, the cables are cut, and the descent stage soars off to a safe distance. I imagine it just kind of lands or crash lands somewhere else. And it's done. There's something very simple and straightforward about this moment of the landing. It's almost like a drone from Amazon delivering a package to your front lawn.

Christine Malec:

Huck huck huck!

JJ Hunt:

It's really deceptive, it looks really simple. But when you realize that the wheels of this vehicle are also the landing gear - that's remarkable.

Christine Malec:

Whistle.

JJ Hunt:

That's really cool. And then this video gives us a final cinematic closeup of the rover on the surface of Mars. And again, everything looks very, very real, very tangible. The treads on the tire, the recognizable machinery. There are the words Perseverance, and NASA 2020 on the folded arm in the trademark NASA font that a lot of us are familiar with. There's a shadow that falls on the cracked floor, the cracked desert floor. It's all again very terrestrial. It's all very real, it's recognizable. And then we pull back further and further as you can only do in a computer animation. We pull back further and further and further until the rover is just a tiny little speck all alone with nothing around but this copper- olored desert, a rocky ridge distant mountains. It's left a l on

Christine Malec:

Oh, Oh, that is so cinematic.

JJ Hunt:

They do a very good job with this video, I gotta say. So if all goes according to plan, that's what this'll look lik . That's the entry, descent a d landin

Christine Malec:

Oh my gosh, that was epic. That was epic. I want to mention something very, very cool, which is that there are two microphones on board for mainly for scientific purposes. But we will definitely have a link to this in our show notes. But if you just Google Mars Perseverance microphone on board, you'll you'll get an article and it's it's possible we might even get to hear the wheels crunching down on the surface of Mars!

JJ Hunt:

Heh heh heh.

Christine Malec:

I'm so excited! We love making this podcast. If you love hearing it, perhaps you'll consider supporting its creation and development by becoming a patron. We've set up a Patreon page to help cover the costs of putting the show together. You can contribute as a listener or as a sponsor to help ensure that accessible and entertaining journalism continues to reach our community. Visit patreon.com slash talk description to me that's pa t ar e o n.com slash talk description to me. Have feedback or suggestions of what you'd like To hear about here's how to get in touch with us. Our email address is talk description to [email protected] Our Facebook page is called talk description to me. Our website is talk description to me.com and you can follow us on Twitter at talk description.

The Perseverance Rover
The Ingenuity Helicopter
The Martian Landscape
Entry, Descent, and Landing