There is no sound in space.
on 08 Jun 2015 20:46
on 09 Jun 2015 09:56
on 09 Jun 2015 10:36
apotheosis wrote:Did Matt Damon just walk off the set of Interstellar and straight onto this one wearing the same suit?
And Tech, stop with the 'no one else likes this but me' stuff. Makes you sound like an insufferable coont.
on 09 Jun 2015 11:19
Ares 4 will be landing at the Schiaparelli Crater, 3,200km away. In fact, their MAV is already there. I know because I watched Martinez land it.
It takes 18 months for the MAV to make its fuel, so it’s the first thing NASA sends along. Sending it 48 months early gives it plenty of extra time in case fuel reactions go slower than expected. But much more importantly, it means a precision soft-landing can be done remotely by a pilot in orbit. Direct remote operation from Houston isn’t an option; they’re anywhere from 4 to 20 light-minutes away.
Ares 4’ s MAV spent 11 months getting to Mars. Using less fuel and taking a longer route, it got there around the same time as us. As expected, Martinez landed it beautifully. It was one of the last things we did before piling in to our MDV and heading to the surface. Ahh, the good old days, when I had a crew with me.
I’m lucky. 3,200km isn’t that bad. It could have been up to 10,000km away. And because I’m on the flattest part of Mars, the first 650km is nice, smooth terrain (Yay Acidalia Planitia!) but the rest of it is nasty, rugged, crater-pocked hell.
Obviously, I’ll have to use a rover. And guess what? They weren’t designed for massive overland journeys.
This is going to be a research effort, with a bunch of experimentation. I’ll have to become my own little NASA, figuring out how to explore far from the Hab. The good news is I have lots of time to figure it out. Almost 4 years.
Some stuff is obvious. I’ll need to use a rover. It’ll take a long time, so I’ll need to bring supplies. I’ll need to recharge en-route, and rovers don’t have solar cells. I’ll need to steal some from the Hab’s solar farm. During the trip I’ll need to breathe, eat, and drink.
Lucky for me, the tech specs for everything are right here in the computer.
I’ll need to trick out a rover. Basically it’ll have to be a mobile Hab. I’ll pick Rover 2 as my target. We have a certain bond, after I spent two days in it during the “Great Hydrogen Scare of Sol 37.”
There’s too much shit to think about all at once. So for now, I’ll just think about power.
Our mission had a 10km operational radius. Knowing we wouldn’t take straight-line paths, NASA designed the rovers to go 35km on a full charge. That presumes flat, reasonable terrain. Each rover has a 9000Wh battery.
Step one is to loot Rover 1’ s battery and install it in Rover 2. Ta-daa! I just doubled my full-charge range.
There’s just one complication. Heating.
Part of the battery power goes to heating the rover. Mars is really cold. Normally, we were expected to do all EVAs in under 5 hours. But I’ll be living in it 24 ½ hours a day. According to the specs, the heating equipment soaks up 400W. Keeping it on would eat up 9800Wh per day. Over half my power supply, every day!
But I do have a free source of heat: Me. A couple million years of evolution gave me “warm blooded” technology. I can wear layers. The rover has good insulation, too. It’ll have to be enough; I need every bit of power.
And because I need to bundle up anyway, I can deactivate the heater outright and use all the power for motion (minus a negligible amount for computer, life support, etc.)
According to my boring math, moving the rover eats 200Wh of juice to go 1km, so using the full 18,000Wh gets me 90km of travel. Now we’re talkin’.
I’ll never actually get 90km on a single charge. I’ll have hills to deal with, and rough terrain, sand, etc. But it’s a good ballpark. It tells me that it would take at least 35 days of travel to get to Ares 4. It’ll probably be more like 50. But that’s plausible, at least.
At the rover’s blazing 25kph top speed, it’ll take me 3 ½ hours before I run the battery down. I’d like to charge the battery up during the rest of the day. I can drive in twilight, and save the sunny part of the day for charging. This time of year I get about 13 hours of light. How many solar cells will I have to pilfer from the Hab’s farm?
Thanks to the fine taxpayers of America, I have over 100 of square meters of the most expensive solar paneling ever made. It has an astounding 10.2% efficiency, which is good because Mars doesn’t get as much sunlight as Earth. Only 500 to 700 watts per square meter (Compared to the 1400 those spoiled Earthlings get).
Long story short: I need to bring 28 square meters of solar cell. That’s 14 panels.
I can put two stacks of 7 on the roof. They’ll stick out over the edges, but as long as they’re secure I’m happy. Every day, after driving, I’ll spread them out then… wait all day. Man it’ll be dull.
Well it’s a start. Tomorrow’s mission: transfer Rover 1’ s battery to Rover 2.
Weir, Andy (2012-09-27). The Martian (Kindle Locations 974-1020). . Kindle Edition.
LOG ENTRY: SOL 95 Today was all about repairs!
The Pathfinder mission ended because the Lander had an unknown critical failure. Once they lost contact with the Lander, they had no idea what became of Sojourner. It might be in better shape. Maybe it just needs power. Power it couldn’t get with the solar panels hopelessly caked with dust.
Setting it on my workbench, I pried open a panel to peek inside. The battery was a lithium thionyl chloride non-rechargeable. I figured that out from some subtle clues: the shape of the connection points, the thickness of the insulation, and the fact that it had “LiSOCl2 NON-RCHRG” written on it.
I cleaned the solar panels thoroughly, then aimed a small, flexible lamp directly at them. The battery’s long dead. But the panels might be ok, and Sojourner can operate directly off them. We’ll see if anything happens.
Then it was time to take a look at Sojourner’s daddy. I suited up and headed out.
On most landers, the weak point is the battery. It’s the most delicate component, and when it dies, there’s no way to recover.
Landers can’t just shut down and wait when they have low batteries. Their electronics won’t work unless they’re at a minimum temperature. So they have heaters to keep the electronics warm. It’s a problem that rarely comes up on Earth, but hey. Mars.
Over time, the solar panels get covered with dust. Then winter brings colder temperatures and less daylight. This all combines into a big “fuck you” from Mars to your lander. Eventually it’s using more power to keep warm than it’s getting from the meager daylight that makes it through the dust.
Once the battery runs down, the electronics get too cold to operate, and the whole system dies. The solar panels will recharge the battery somewhat, but there’s nothing to tell the system to reboot. Anything that could make that decision would be electronics, which would not be working. Eventually, the now unused battery will lose its ability to retain charge.
That’s the usual cause of death. And I sure hope it’s what killed Pathfinder.
I piled some leftover parts of the MDV into a makeshift table and ramp. Then I dragged the Lander up to my new outdoor workbench. Working in an EVA suit is annoying enough. Bending over the whole time would have been torture.
I got my toolkit and started poking around. Opening the outer panel wasn’t too hard and I identified the battery easily enough. JPL labels everything. It’s a 40 Amp-hour Ag-Zr battery with an optimal voltage of 1.5V. Wow. They really made those things run on nothin’ back then.
I detached the battery and headed back inside. I checked it with my electronics kit, and sure enough it’s dead, dead, dead. I could shuffle across a carpet and hold more charge.
So I knew what it needed. 1.5 volts.
Compared to the makeshift crap I’ve been gluing together since Sol 6, this was a breeze. I have voltage controllers in my kit! It only took me 15 minutes to put a controller on a reserve power line, then another hour to go outside and run the line to where the battery used to be.
Then there’s the issue of heat. It’s a good idea to keep electronics above -40C. The temperature today is a brisk -63C.
The battery was big and easy to identify, but I had no clue where the heaters were. Even if I knew, it’d be too risky to hook them directly to power. I could easily fry the whole system.
So instead, I went to good old “Spare Parts” Rover 1, and stole it’s environment heater. I’ve gutted that poor rover so much, it looks like I parked it in a bad part of town.
Bringing the heater to my “workbench,” I hooked it to Hab power. Then I rested it in the Lander where the battery used to be.
Now I wait. And hope.
Weir, Andy (2012-09-27). The Martian (Kindle Locations 1656-1688). . Kindle Edition.
on 19 Jun 2015 14:41
Gizmodo wrote:The Most Important Thing We Will Need to Survive In Space
None of us would be alive today without plants, and if humans want to survive beyond Earth long-term, we’ll need to bring our leafy greens with us. Eventually, astronauts are going to have to become space farmers.
The Martian wrote:LOG ENTRY: SOL 25
Remember those old math questions you had in Algebra class? Where water is entering a container at a certain rate and leaving at a different rate and you need to figure out when it’ll be empty? Well, that concept is critical to the “Mark Watney doesn’t die” project I’m working on.
I need to create calories. And I need enough to last four years. I figure if I don’t get rescued by Ares 4, I’m dead anyway. So that’s my target: four years.
I have plenty of multivitamins; over double what I need. And there’s five times the minimum protein in each food pack, so careful rationing of portions takes care of my protein needs for at least four years. My general nutrition is taken care of. I just need calories.
I need 1500 calories every day. I have 400 days of food to start off with. So how many calories do I need to generate per day along the entire time period to stay alive for 1400 days total (the time till Ares 4 arrives)?
I’ll spare you the math. The answer is a cool 1000. I need to create 1000 calories per day with my farming efforts to survive until Ares 4 gets here. Actually, a little more than that, because it’s sol 25 right now and I haven’t actually planted anything yet.
With my 62 square meters of farmland, I’ll be able to create about 288 calories per day. I need to bring that up to 1000. I need four times my current plan’s production to survive.
I need more surface area for farming, and I need water to hydrate the soil. So let’s take the problems one at a time.
How much farmland can I really make?
There are 92 square meters in the Hab. Let’s say I could make use of all of it.
Also, there are five unused bunks. Let’s say I put soil in on them, too. They’re 2 square meters each, giving me 10 more square meters. So we’re up to 102.
The Hab has three lab tables, each about 2 square meters. I want to keep one for my own use, leaving two for the cause. That’s another four square meters, bringing the total to 106.
I have two Martian rovers. They have pressure seals, allowing the occupants to drive in ease, without spacesuits, as they spent long periods traversing the surface. They’re too cramped to plant crops in, and I want to be able to drive them around anyway. But both rovers have an emergency pop-tent.
There are a lot of problems with using pop-tents as farmland, but they have 10 square meters of floor space each. Presuming I can overcome the problems, they net me another 20 square meters, bringing my farmland up to 126.
126 square meters of farmable land. That’s something to work with. Not nearly enough water to moisten the soil, but like I said, one thing at a time.
The next thing to consider is how efficient I can be in growing potatoes. I based my crop yield estimates on the potato industry back on Earth. But potato farmers aren’t in a desperate race for survival like I am. Can I get a better yield?
For starters, I can give attention to each individual plant. I can trim them and keep them healthy and not interfering with each other. Also, as their flowering bodies breach the surface, I can replant them deeper, then plant younger plants above them. For normal potato farmers, it’s not worth doing because they’re working with literally millions of potato plants.
Also, this sort of farming annihilates the soil. Any farmer doing it would turn their land into a dust bowl within 12 years. It’s not sustainable. But who gives a shit? I just need to survive four years.
I estimate I can get 50% higher yield by using these tactics. And with the 126 square meter farmland (just over double the 62 square meters I have) it works out to be over 900 calories per day.
That’s real progress. I’d still be in danger of starvation, but it gets me in the range of survival. I might be able to make it by nearly starving but not quite dying. I could reduce my caloric use by minimizing manual labor. I could set the temperature of the Hab higher than normal, meaning my body expends less energy keeping its temperature. I could cut off an arm and eat it, gaining me valuable calories and reducing my overall caloric need.
No, not really.
So let’s say I could clear up that much farmland. Seems reasonable. Where do I get the water? To go from 62 to 126 square meters of farmland at 10cm deep, I’ll need 6.4 more cubic meters of soil (more shoveling, whee!) and that’ll need over 250 liters of water.
The 50L I have is for me to drink if the Water Reclaimer breaks. So I’m 250L short of my 250L goal.
Bleh. I’m going to bed.
Weir, Andy (2012-09-27). The Martian (Kindle Locations 263-302). . Kindle Edition.
on 12 Nov 2015 11:51
on 12 Nov 2015 16:21
on 24 Jun 2016 14:00
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