InSight into Mars

They marked the eighth time the United States has managed to land a mission on Mars successfully. So we're gonna take a look at this lander, what it does, and what it's mission parameters are. Before I get into Insights specifically, it's a good time to chat about the logistics of just getting to Mars in general. You may have heard that if we were to send people to Mars, they need to stay there for about two years before they could return. So why is that, Well, it's because of

the respective orbits of Earth and Mars. Mars is further out from the Sun than the Earth is, and a Martian year lasts six hundred eighty seven Earth days or six hundred sixty nine souls or Martian days compared to an Earth year, which has of course three hundred sixty

five days, unless it's a leap year. So there are times when Earth and Mars are relatively close, and by relatively I mean nearly thirty five million miles or fifty six million kilometers apart, and there are other times when they are opposite each other with the Sun in the center, they're bout as far apart as they possibly can be. Space travel is expensive and it requires a lot of fuel.

Fuel ways a lot, and the heavier year spacecraft gets, the more fuel you need, so you end up in this sort of cycle up to a point where you have to keep adding fuel to lift not just the spacecraft but the fuel you are already have in it. So that means you get to be super careful with how heavy your spacecraft is so that you can be very efficient with the amount of fuel you're going to

need to get to your destination. So that includes playing your trips so that you travel the shortest possible distance between two points, taking the least amount of time to get from point A to point B. So you want to set a launch date in advance of a time when Earth and Mars are going to be relatively close to each other. That's the launch window we want to look at. But of course Mars is moving the whole

time as his Earth. So really you're setting a launch window to aim at the point in space where Mars is going to be in several months after the launch. It's actually pretty complicated stuff. I mean, they do call it rocket science. Even when you take advantage of orbital paths, you're still talking about a trip that will take between six and eight months using conventional rockets, So you have

to settle in for a long trip. Now, once you get to Mars, you won't be able to leave right away if you have a method of leaving in the first place, you would have to wait around for Earth and Mars to be nearing one another again. And a launch window for the minimal amount of energy needed to get between the two comes around only every two Earth years and two Earth months, So you need enough fuel to make the trip home, or you need some way to make the fuel at your destination, such as Mars,

so that you can make the return trip. Now, you could make going to Mars a one way trip, and considering how hostile the planet is and how hard it would be to get back. That's probably not entirely unrealistic, if I'm being honest. We'll talk more about that in our next episode, but before we decide to shove someone off into space for a life sentence on Mars, we can send other craft to the red planet, and in fact we have that includes orbiters, which, as the name suggests,

orbits the planet and gathers information about it. Landers, which has the name suggests, lands on the planet and gathers information about it. And rovers, which, again the name tells you everything you need to know. It roves about on the planet, gathering information and you know, doing sick donuts, and the name is pretty much tell you everything you need to know about them, at least in a general sense. So landing on Mars, particularly if you want to do

a soft landing, is pretty challenging as well. That's because of several factors. One is that the Martian atmosphere is much thinner than Earth's, so stuff like parachutes are less effective. They do work, but they don't slow down to scent quite as effectively as they would if you were using them on Earth. However, the atmosphere is thick enough to

cause heating problems. Upon entry of the atmosphere, the spacecraft starts to come in at a very high speed, it hits the atmosphere, starts to compress the atmosphere in front of it, and it begins to heat up rapidly. So whatever your spacecraft is, you need some really good heat shielding to take care of that problem. That of course adds to the weight of the spacecraft. And while gravity on Mars is less intense than on Earth, the gravity on Mars is about point three eight times out of

Earth's gravity. Descending from Martian orbit still means you're going at a speed that's plenty fast enough to cause serious damage when you hit the ground, So you have to have a way to slow your descent. One way to offset that incredibly fast descent is to have special retro rockets on the landing craft and to fire those before you land so that you have a nice and gentle touchdown. That really would help slow the descent. But here's the thing with these craft that we're sending the landers and

the rovers. For the ones that we're using for a soft landing, they have to rely upon a fully automated system. Because the distance between Mars and Earth is such that it takes several minutes for radio signals to pass back and forth between the two. Radio signals move at the speed of light, but the distances involved are so great that even light requires a few minutes to get the

job done. So if you were looking at a video feed from the spacecraft, let's say that there's a live camera feed and it's able to send video back to Earth. This would be unrealistic, But let's say it's happening. What you would actually be looking at would be video from several minutes ago. The video footage would be several minutes old, because that's how long it took for the information to travel from the the lander or rover on Mars to get to you on Earth. Sending a message to the

lander would obviously take more time. So let's say you see a picture and you think, oh, well, that's that rock over there is interesting. I want this thing to go grab that rock, and you send a command to the device. Well, keep in mind the picture you're looking at it several minutes old. When you send the message, it takes several more minutes for it to get back.

The device then has to react to it, and it will take even more minutes for you to know that anything actually happened, so there's no way to make any adjustments in real time at all. So that's why the system has to be fully automated. When it's landing, there's no way to step in and take control of it as a remote pilot, because the distances are so great that by the time you're sending commands, the thing you're trying to command has already crashed into Mars. So you

have to create this automated system. The landing process for this lander would take about six and a half minutes from the point it enters the Martian atmosphere to the point that it landed on the surface. NASA would call this the seven minutes of Terror. That six and a half minutes would include every single thing that would have to happen in this process of entering the atmosphere all the way to the point of firing the retro gets

at settling down on the surface of Mars. If anything were to go wrong at any stage there, whether it maybe it's a parachute that fails to deploy, a thruster that fires a second too late, whatever it would be, all would be lost. Chances are you would have a

total loss of the spacecraft. In addition, that distance between Earth and Mars would mean we wouldn't even know that something had gone wrong until about eight minutes after it had gone wrong, So if the lander were to crash and be destroyed, it would have been destroyed for eight minutes before we knew about it. Also, it meant that picking a landing site is incredibly important. You want to find the best possible site to target so that your lander or rover, whatever it may be, has the best

possible chance of survival. NASA had to find a spot that not only would be optimal for whatever the mission objectives happened to be. In this case, it's all about measuring various uh features of Mars, but it also has to be geographically favorable for that successful landing and for a continued operation. Sou with the case of the Insight, it also meant that having to pick a spot that would be favorable for solar panels, because that's how the

the Insight lander recharges its batteries. So for that reason, they chose a spot near the equator because that would maximize solar exposure, and because you're relying upon automated systems to guide the landing craft to the surface. You also have to pick a location that's relatively flat and free of large rocks or boulders that could cause the craft to topple over after touchdown. That is a tough thing

to look for on Mars. Mars is very very rocky and uneven in many places, but the team in NASA eventually chose a region of Mars called the Elysium Planetia. That was way back in when they made that choice. That first, NASA had more than twenty potential landing sites identify light. Then the team directed the Mars Reconnaissance orbiter to gather images of those sites so that they could choose the best candidates. Each potential site measured eighty one

miles by seventeen miles in an elliptical shape. That's a hundred thirty kilometers by twenty seven kilometers. The insight landing location is about three d seventy miles or six hundred kilometers away from where the curiosity rover is, so it's probably not going to get a visit from its fellow robot anytime soon, and a monitor the progress of the actual landing. NASA sent up a pair of small satellites

called cube SATs. Along with the Insight These were the first two cubes AT spacecraft to journey into deep space. They are communications relay satellites. These particular cube SAT satellites are the Jet Propulsion Laboratory designed and built them. The basic unit of a cube sat is a box about ten centimeters or four inches to a side, and CubeSats can be made up of multiple units, and the two that were hitching a ride with Insight were each six

units large. The job of those two satellites involved flying by Mars and listening for Insights signal that would indicate a successful landing. The CubeSats both have UHF capabilities, though they can only receive UHF radio signals and X band capabilities,

which meant they could receive and transmit over those frequencies. Interestingly, those satellites separated from the launch vehicle that was an Atlas five rocket, and they did so independently of the Insight cruise spacecraft, and so they flew to Mars on their own trajectories and with their own course adjustments in order to get to where they needed to be for

the actual landing procedure. The satellites also served as a pilot program to test the viability of a bring your own communications relay with a short development cycle into deep space, and it worked. Now I have a lot more to say about INSIGHT and what it does, but before we get to that, take a quick break to thank our sponsor. The full name for INSIGHT is the Interior Exploration using Seismic Investigations, GEO Daisy and Heat Transport. And I have

a sneaking suspicion. This is another case of a mission getting a fun name and then a project team tries to work backward to make that name into an acronym. But I don't know that for sure. The purpose of the mission is to deduce how celestial bodies that have a rocky surface are formed, how do they come to be. This would include planets like Earth, as well as satellites

like our Moon, and of course planets like Mars. The Lander is going to do this by using several scientific instruments to study the deep interior of Mars, and then the team back on Earth is going to take the information and form hypotheses to explain the formation process. The Lander will also gather data that will allow scientists on Earth to make educated guesses about Mars's core. So this

is really cool. This is all about observing planet's behavior in a way and then drawing conclusions about what that means for the planet, what how the planet is made up, you know, what sort of core it has, that kind of stuff, and it's all about working backward based upon these observations. I love this kind of science. Insight is kind of like the Phoenix Lander, and that both of those are stationary robotic platforms, so it's not like the Spirit,

Opportunity or Curiosity rovers. Those are all robots with wheels that can move around the surface of Mars. Actually, the Opportunity and Curiosity rovers are still in operation to this day. Opportunity landed on Mars in two thousand four and Curiosity landed in two thousand twelve, and there's still kind of roaming around. But insights job is to monitor conditions from a set location over the course of a Martian year plus forty or so martian days. Insight is a pretty

large lander. NASA describes it as being about the size of a big nineteen sixties convertible. That's a quote, but this is tech stuffs. Let's get technical. What are the specs for the Insight Lander, well, it is six ms long. That's about nineteen ft eight inches, assuming you're measuring it when it's solar panels are deployed. Again, we'll talk about the solar planel panels in just a minute. It's got a width of one point five six ms that's about

five ft one inch. Uh. The deck height, so the the top surface of the main portion of the lander ranges from eighty three centimeters to one centimeters tall or thirty three to forty three inches. The whole thing weighs in at a smelt three d sixty ms. Technically that's its mass. Uh we If we're expressing it in pounds, it would be seven pounds here on Earth. Remember, on Mars the mass is the same, but it weighs less because again, mars Is gravity is a little more than

one third that of Earth's gravity. The lander has a lot of cool gadgets attached to it. It draws power through batteries that are recharged by those solar panels I had mentioned. Those actually had to deploy after Insight touched down, before they were all folded up and tucked away on the sides of the platform for safety. About an hour after touchdown, they began the deployment phase and this involves unfolding and then they can start catching the sun's rays.

And there's a great website for the lander over at NASA's Jet Propulsion Laboratory that shows animations of the solar panels deploying as well as the other tools and how those get deployed. The animations are fantastic, they really help a lot, So I highly recommend if you're interested in the Insight Lander checking out the interactive web page over at the Jet Propulsion Laboratory because it's it's fantastic and it looks super cool. Uh. The panels, the solar panels

are decagonal. That means they have ten straight sides and angles. You know, an octagon is eight sides and eight angles. A decagon is ten, so they're kind of circular in shape, but they have those flat edges. The panels measure about seven feet or two meters across, and there are two of them. Has a pair of these solar panels. According to one NASA web page, the combined surface area of the two solar panels is quote as large as a ping pong table end quote. So you know, some light

recreation on Mars. If you if you decide that it's served its purpose, I guess they're able to generate about three thousand what hours of electricity every martian day. Another important component on this lander is its robot arm. The arm has three degrees of freedom and those roughly translate to a human shoulder, elbow, and wrist joint. The arm has four motors to control the movements of the arm and those joints. And at the end of the arm, instead of there being a hand or like a claw,

there's actually a grapple. It's attached by a cable. It dangles at the end of the arm, and this is used to grasp the various tools on the platform deck in order to lift them up and deploy them onto Mars' surface. So it kind of looks like one of those claw games you see in arcades or in the Toy Story film. It kind of looks like that, except that the claw does not descend and ascend. The cable doesn't unwind and wind. It stays the same length, so the arm itself will

tilt up or down. But the claw does dangle from a cable. It just the cable itself is stationary. It's also got a firm grip, which also means it's not really like a claw game because those things are rigged I tell you, stupid Teddy Bear. Anyway, it's a super cool way of manipulating objects on the lander, and again

the animations are really fun to watch. There's a camera mounted on this arm it's actually between the elbow and wrist joints that can provide NASA images of Mars and help the team make sure that the instrumentation that's attached

to the platform is properly deployed. In fact, it's called the Instrument Deployment Camera or i d C. So the main purpose for the arm is to place the two of the three main sensors on the platform, two of the three main scientific experiments really on the surface of Mars. More on those two experiments in just a moment. The lander actually has a second camera. That one is mounted

just below the surface of the deck. This one is called the Instrument Context Camera or i C SEE, and it has a fish eye perspective with a field of view of about hundred twenty degrees. It's aimed at the ground near the lander that serves as the landers work space. So both cameras have a resolution of one thousand, twenty four by one pixels, which is not quite a two megapixel image. And in an interesting analogy, NASA has compared the mission to a human getting a medical check up.

The Insight Lander is going to check Mars's vitals, which includes the planet's pulse, temperature, and reflexes. So what was that all about. Well, these are all kind of cute ways to talk about the main instruments and scientific projects connected to the Insight Lander. So let's start with the pulse, the pulse of the planet in this case. In this context,

it refers to the seismological events on Mars. So things that make the earth shake, or I guess I should say Mars shake, it's not the earth there so, or as my former co host Crispalett would say, stuff what makes the ground shake. One of the instruments inside has is a special seismometer with a super cool wind and thermal shield. The seismometer has a cable tether that connects it back to the Insight Lander, and the cable's purpose is twofold. It contains both the power line and the

data line for the seismometer. So this is the way that the lander can provide electricity to the seismometer, and the seismometer can feed data back to the lander. The illustrations I've looked at make it a little like the insight lander is kind of walking a weird, lumpy robot dog. The lander's robotic arm is responsible for lifting the seismometer off the platform and placing it on the surface of

Mars near the lander itself. Then it has to put the uh the thermal and wind shield over the seismometer. The purpose of the shield is pretty much what sounds like. It's meant to protect the seismometer from gusts of wind, primarily that would possibly cause the seizemometer to register false readings. If the wind pushes the seismometer around that it's going to start registering as if there's an earthquake or Mars quake.

I guess this way, the shield blocks that wind and the seizemometer just keeps on, you know, monitoring the movement of the ground beneath it. The wind and thermal shield is made out of aluminum. The main shielding part on the top anyway, is made out of aluminum. It looks like a dome with little lander legs almost like a little ufo. It also has a metallic skirt that hangs down beneath the dome. It's the thermal skirt. It's actually

made out of gold. And then this gold skirt has a bottom edge made out of and I am not making this up, honest to goodness, the edge is made out of chain mail, like the stuff that nights used to wear back in medieval times. How cool is that? So this chain mail actually serves a couple of different purposes. For one, it's it's heavier than the skirt is, so it helps pull down on the skirt while the little arm is lifting the shield up off the deck of

the lander. The chain mail provides the weight to help pull the skirt straight so that it goes down all around the sides of the seismometer. Also, the chain mail is flexible, so it can drape over any small pebbles or rocks to allow a pretty good seal of the shield over the seismometer. The shield itself is about fourteen inches or thirty five centimeters tall, twenty seven inches or sixty nine centimeters in diameter, and has a mass of twelve kilograms, which means here on Earth it would weigh

about twenty six and a half pounds. I'll finish up this section by giving a quick overview of how seismometers work, and then we'll talk about the other two experiments in the next section. So typically we would pair a seismometer up with some sort of recording device, which would mean that we would have a seismograph. That's when you have

the two components together. So a simple version of this one that you might see here on Earth uh, an old school simple mechanical version of a seismometer would be a frame that has good contact with the ground. So you've got a frame that is set on whatever surface you're measuring. Suspended from the top of that frame would be a weight on a spring, and the weight would

hold some sort of writing utensil, like a pen. That pen the end of it would rest against a strip of paper that could be rolled or pulled in such a way that the pen is drawing a line on that strip strip of paper as the paper moves past it. If there's a trimmer, the frame is going to move along with the ground, but the suspended weight will tend to remain motionless as it is largely isolated from the ground and the frame and an object at rest tends

to stay at rest. So you can think of it as the frame and the earth and everything else is moving up and down. The weight is kind of just staying where it was, and that means that the paper is going to be moving up and down against the pen. Not the pen against the paper. The paper itself is moving up and down because the ground is moving up and down. And that means that the pen is gonna

start drawing squiggles on this paper. And so you could look over the paper and wherever you saw squiggles, you'd say, all right, well that was where there was an earthquake or an aftershock, or maybe a large truck drove by

or whatever. The seismometer on the insite works on a similar principle, except instead of holding a pen, instead of it being mechanical, the relative motion between the weight and the frame would create an electrical voltage, and changes in that voltage are recorded by a computer system on the insite and transmitted back to Earth, and those are interpreted as the various quakes. I have a lot more to say about the experiments aboard the Insight, but first let's

take another quick break to thank our sponsor. So the second vital sign Insight is going to monitor is temperature. The deck of the lander has a temperature censor of its own to give surface readings. But what I think is super interesting is what is called the HP three instrument. HP three stands for heat flow and Physical Properties probe.

It's another tethered instrument that connects back to the lander, and like the seismometer, the robotic arm has to lift up the HP three and then place it on the surface of Mars in the work space in front of the lander. Inside this instrument is a probe. It looks like almost like a spike, and it's called the mole and it's tied. It's a type of pine traumater. I didn't even know that was a word until I did this research, but that essentially is a tool designed to

pay to trate a surface. That's the name pentatrometer. In this case, we're talking about the Martian soil. So inside this spike, which again is is got a cable out the back of it that goes back up into the instrument. The cable is held in a way where it can be fed out gradually, so that as the spike is digging down it can continue to have enough slack to do this. But inside the spike, inside the penta traumeter is a weight on a spring. Essentially, that's a hammer.

It's inside the spike. So imagine you've got a nail or a railroad spike or something like that. But the hammer for this nail or spike is actually inside the spike or the nail itself, so it's a self hammering nail. The mechanism draws power from the lander to pull back the weight that compresses a spring, and then you latch it into place. When it's completely compressed, you can unleash

this weight. The spring will expand rapidly, pushing the weight down so that it collides with a little section at the very tip of this probe, and it's like a hammer knocking a nail, and it starts to hammer the spike down. This is actually a pretty slow process. It does not happen super fast. It's not like one, uh one bash and suddenly the spike is several feet in the soil. That's not the way it works. It's very gradual.

So by keeping a careful tension on the cable so that the spike is properly positioned, and by doing this several times, you start to drive the spike down into the soil. It's gonna take months, but ultimately this mole is going to dig down to a depth of about five meters or sixteen feet, which is deeper than anyone has dug on Mars up to this point as far as we know anyway. But obviously this instrument is doing

more than just digging a hole on Mars. I mean, that's super cool the way they're doing it, but that's not the only thing it's doing. The probe and the tether that's trailing behind it contains temperature sensors, and those sensors will monitor the heat flowing from the interior of Mars, which will help tell scientists what the inside of Mars is like. It could inform scientists about how active Mars is and whether it's made out of similar stuff as Earth.

The probe isn't just listening either. As the probe digs down at certain stages, it will occasionally stop and it will put out a pulse of heat of its own. Then it will monitor how that heat flows through the material around the probe. So if that material happens to be a good conductor like metal, like coppers. A great conductor of heat, the heat will decay very quickly, it'll move outwards through this conductive material. But if it's a poor conductor, more like glass, the heat's going to stick

around a lot longer. The HP three probe weighs in at about six point five pounds at least it would here on Earth. That means it has a mass of about three kims and it only consumes to watts max as the probe starts to dig down into the Martian soil. The last of the three big experiments would be a pair of RISE antennas on the deck of the lander. These would not be removed from the deck and placed on the Martian soil. They will stay on the lander.

RISE stands for Rotation and Interior Structure Experiment. These antennae will track Mars's motions as it rotates, so essentially, it's all about detecting that wobble. So how much does Mars wobble around? Knowing how much it wobbles around will tell scientists valuable information about Mars's core. How big is Mars's core, Is it a solid core, is it a liquid core? What elements besides iron might be in the core. Well,

the way Rise works is actually pretty darn simple. It listens for an incoming signal from Earth, and then it sends the signal back to Earth. This will reveal the precise location of the lander, well precise location from a few minutes in the past. Because again the signals can only travel as fast as light, it may take a few minutes for that to happen, depending upon where Earth and Mars are in their respective orbits. But back on Earth, computers will take this this return signal and analyze it

for changes and looking for evidence of Doppler shift. I've talked about Doppler shift many times on this show, but just so you remember, if you've got something moving in a wave, whether it's a radio wave or a physical wave, whatever it may be, h it has a certain frequency. And if the wave is coming from a stationary object and then it hits a different state stionary object, any reflective waves. Reflective waves that come back to the source

are going to be unchanged except for their direction. Right that you're gonna get back the same frequency of wave if both objects are stationary, But if the objects are moving closer to each other, the returning wave is going to be compressed, so it's going to be at a higher frequency. If the two objects are moving away from each other, the wave is going to be elongated to

a lower frequency. And by measuring these changes, scientists will be able to figure out how much Mars is wobbling around as it orbits the Sun. Now, Earth wobbles every eighteen years thanks to the Moon's pull on us, and we already know that Mars does in fact wobble, In fact, it wobbles over the course of a single Martian year, but we don't know to what degree how much does it wobble. We know it does, we just don't know

how uh intense that wobble is. So the Rye his instruments will provide more information to fill in this knowledge gap. And the amount of wobble planet has depends partly on what is in the delicious neugute center of that planet. So, as NASA points out in a really helpful web page, a hard boiled egg is going to spend faster than a raw egg. Also, planets that have liquid cores will

wobble more when they spend. Planets with a solid core will wobble less, and this in turn can help us make other hypotheses about why Mars has a very weak magnetic field in comparison to Earth's magnetic field. So it's all about learning more about why is Mars the way it is and more about how Mars actually is. There are other instruments on the lander that aren't getting quite the same level of coverage. The lander has an atmospheric

pressure sensor, for example. It also has a uh F antenna to allow the lander to communicate to satellites that are in Martian orbit, which includes the Mars Reconnaissance Orbiter and the Mars Odyssey Orbiter, both of which pass over in Sight two times every Martian day. And there are other satellites that can chat with as well, like the European Space Agencies Trace Gas Orbiter or NASA's Mars Atmosphere

and Volatile Evolution Orbiter also known as MAVEN. It can talk to those in a pinch if it needs to. So Insight will stand on Mars doing its thing for at least a Martian year plus some change, maybe longer things continue to work out properly. Sometimes these missions can go well beyond their initial projected phase, and if NASA can figure out other things to do with the material that's already there, then that is incredibly helpful. There's some

other elements on it as well. There's a reflective surface, for example. They could be used to locate the precise position of the lander. You just direct a laser at it and look for the reflection. I'm sure we'll learn tons of interesting things about Mars using this device, and probably a lot about Earth as well, which pretty exciting stuff. Now, in our next episode, I'm gonna stick with Mars for

a little bit. I'm gonna talk about the various proposals to send people to Mars and what that would entail, and we'll talk about why it would be super hard to do and why some people like Bill and the Science Guy are skeptical that we're ever going to actually go there for a prolonged stay. And maybe we'll also talk about why Elon Musk thinks there's a decent chance he's gonna end up there. So tune in tomorrow to

hear that episode. If you guys have any suggestions for future episodes of tech Stuff, whether it's a specific technology, that type of of gadget that you've always wanted to know more about. Maybe it's a company history that you want to know more, or a person in tech let me know. Send me an email. The addresses tech stuff at how stuff works dot com. Don't forget to go

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