Maps page

I’ve decided that, since I’ve been more serious about the map-drawing lately, that I would take my generic photography/art web page and focus it specifically on my maps as a little online showcase. This qualifies as an update to my web presence, so here I go, writing about it on the blog.

It’s here, on my main site: http://www.josephshoer.com/personal/images.html

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Let’s go to Europa already!

I’ve been thinking I should write something about the recent discovery of geysers from Europa’s subsurface ocean, but Casey Dreier at the Planetary Society blog basically said everything I want to already.

Europa appears to have all the ingredients for life as we know it: liquid water, energy sources, organic molecules. Scientists have known these things since the Galileo mission to Jupiter. But we haven’t gone back to look for life under the ice – because designing and mounting a mission to do so would be a multi-year, expensive effort. It’s much simpler, and less expensive, to think about smaller missions to Mars, which could launch at a cadence of once every couple years. However, the scientific, societal, psychological, educational, inspirational, and public reward of discovering extraterrestrial life certainly would make a multibilliondollar Europa mission worthwhile.

What the new discovery gives us is easy access to Europa’s subsurface material. Perhaps we can sail a probe through these geyser plumes, testing for biological components. Perhaps we can trawl a few space squid while we’re at it. The easy access, while not up to the same level as Mars, certainly makes a Europa mission easier to think about than one that has to drill through a hundred kilometers of ice!

 

Posted in Science, Space | 1 Comment

This one has a sob story

New map! Here it is, in my studio:

“Archipelago”

This map depicts an island chain, with no particular raison d’être. Hence, no labeled place markers or accompanying glyphs.

I like this one because it contains some of the most careful, subtle, and successful color-shading work I’ve done yet. I think I got more – in terms of both cartographic significance and artistry – out of the coloration than I’ve done with line in many other maps. I spent a good time blending and brushing the watercolors.

Shady islands

In “Archipelago” (because, hey, I think I’ve got to start naming these maps) I spent a significant amount of time on the water, too. Not as much as on the land, mind you, but still – a good fraction of the coloring phase effort went into adding depths to the water and blending the surface together. I wanted to hint at shallows, deeps, and reefs. The lines enhance the effect, with additional shoreline markings hinting at ranks of breakers where beaches slope gently into the sea. The extra coast markings give the impression that you could walk from island to island, getting only your feet wet.

Hopping from place to place and color to color

Many of the same colors that are in the land are also in the water, and vice-versa. Both the mesa tops and the deepest part of the sea have purple in them. The arc of the ocean includes some red and orange – and the grasslands have some blue. In some places, only an ink line and a change of texture (from smoothly blended terrain to the more roughly and unevenly applied waves) distinguishes land from water. There’s a lot of small variation in the colors, bringing out the forests, grasslands, beaches, and stone. There are some lighter ink icons showing regions of thicker vegetation or adding texture to rocky terrain, but for the most part, it’s color doing the lion’s share of the work. This is a bit new: though I’ve been coloring the maps all along, several of my previous maps used color as an enhancer to the ink lines; so far only Zarmina has a similar level of color shading in addition to the ink. I am very pleased with the effect and I think that the map makes a great addition to my growing collection. (I’m up to one in a nice frame, one tacked to the wall in a poster frame, two gifted away, two completed and idling about here somewhere, four works in various stages of slow or rapid progress, and three at the conceptual stage.)

And then I ruined it.

I decided that I needed something else to add focus to the grasslands on the largest island, since most of those regions are yellow and open, and I didn’t want them to appear as deserts. I diluted some india ink to produce a lighter gray ink shade, took out my super-fine pen, and happily added a few regions of hatch marks, with the intention of denoting tall, grassy plains. Amber waves of grain, and all that. Perfectly logical. I was a bit hesitant when I started, but recalling the tremendous success of the inkwash map in a similar situation, I took a deep breath and committed pen to paper.

Plains of sticks? The ground has patchy five o’clock shadow? I don’t know.

Live and learn.

 

Posted in Art, Maps | 3 Comments

“Gravity”

I’ve been a delinquent spacecraft engineer, and didn’t see “Gravity” until today.

In short: it was awesome. It’s a tremendous story about courage, fear, perseverance, the human spirit, our ability to solve the most insurmountable problems, and triumph in the face of adversity. It’s also visually, sonically, musically, and generally aesthetically breathtaking. The integration of the stunning visuals, physically accurate sound, camera movement through space and spacecraft, and music was extraordinarily well integrated into a complete artistic whole.

And, although the events depicted in the movie would not (or could not) play out exactly as shown, they are all plausible from a physics standpoint.

Everyone should go see it. And, yes, see it in 3D – because this is the first movie I have ever seen in which the 3D adds to the visuals and the drama.

Don't let go.

Don’t let go.

Before I read any other physicists’ reviews, I’m going to go through some of the concepts and sequences in the movie, make a few points about the physics involved, and then explain why I am totally fine about it all.

Spoilers ho!

Continue reading

Posted in Science Fiction, Space, Wow | 6 Comments

Orbiting magnetic balloons

I recently got the following question:

Let’s say I have a 500kg balloon floating in the stratosphere at fixed altitude with solar cells collecting 10kw from the sun, then my computation shows that if this energy can be converted to horizontal magnetic propulsion by repelling against the earth’s magnetic field at 100% efficiency then it could reach escape velocity in about one month. This is possible because at this altitude the air resistance is quite small so it is almost like pushing at an air hockey which does not require much force to get it to speed up horizontally. … My question for you here is that in reality how close to practicality is the design of this ‘spacecraft?’

Launch costs are one of the big drivers in the space industry, and the propellant required to get a spacecraft up to orbital speed is a major part of that cost. If we could use some sort of “propellant-less” means to get a vehicle into orbit, we could revolutionize the whole space industry. In fact, this is an idea that my grad school research group once brainstormed about during a lab meeting: push on the Earth’s magnetic field. If we start pushing from high altitude, where air resistance is small, then we just have to wait long enough to accelerate our spacecraft up to at least low Earth orbit speed (about 7 km/s). Launches might take a long time, but they would be far cheaper and easier.

As long as we can push on the spacecraft with a net force in the direction of its velocity, then it will accelerate. So, the first question we come to is this: how much drag force do we need to overcome? That force will provide us with an estimate of the minimum force our electromagnetic device needs to produce.

Air resistance causes a force in the opposite direction to an object’s velocity. For a sphere moving through the air, this force has a magnitude equal to 1.1 d A v2, where d is the air density, A is the cross-sectional area of the sphere (pi r2), and v is the object’s velocity. Let’s suppose we mount our 500 kg spacecraft on a high-altitude balloon that can get all the way up to 30 km altitude before we engage the magnetic propulsion device. At that altitude, the atmospheric density is in the ballpark of 0.02 kg/m3. (I’m reading off of the 1962 US Standard Atmosphere graph on Wikipedia, since I can’t look at NASA’s web resources. Thanks, Tea Party!) Now we have d.

Next question: how big is the balloon? Way back in Ancient Greece, when Aristotle had the original “eureka!” moment, he realized that objects float in a fluid when they displace a weight of fluid equal to their own weight. (Equivalently, they displace a mass of fluid equal to their own mass.) So, our 500 kg balloon-based vehicle has to displace 500 kg of air – and if it’s floating at a level where the air pressure is 0.02 kg/m3, then that means the balloon takes up a volume of at least 25,000 m3. That’s a sphere 36.3 m in diameter. (Note that here I’m assuming that the mass of the vehicle includes the mass of the balloon and of the gas we pumped in to inflate the balloon. What finally gets to orbit will be less than 500 kg.) So: A is about 1035 m2.

Now we have an estimate for the drag force magnitude on our electromagnetic launch vehicle at 30 km altitude, of about 22.77 v2. If we start our electromagnetic devices pushing, the spacecraft will start to move – but it will eventually settle on a steady-state speed at which the drag force and propulsive force balance each other. Here’s the bad news: even though the atmosphere is not very dense 30 km up, that v2 in the drag equation will really get us as we reach higher and higher speeds. If the balloon gets going at 1 m/s, the drag force will be 22.77 N. If we reach 10 m/s (about normal human sprinting speed), the drag force is 2,277 N. If we tried to accelerate the balloon all the way up to 7 km/s at this altitude, putting the vehicle in orbit, then the drag force will get to over one billion newtons! It’s not feasible to build a compact device that could push on the Earth’s magnetic field and generate this kind of force.

You might get the idea that as we accelerate, we can also gradually increase the balloon’s altitude. After all, if the air gets less dense, that drag force will decrease. With less resistance opposing our spacecraft, we don’t have to work as hard to accelerate it.

There are two problems we’ll run into if we follow this idea. First, while going up in altitude makes our spacecraft encounter less atmospheric density, it also has a weaker magnetic field to work with. At these high altitudes, atmospheric density is very much like an exponential decay. But the magnetic field from a dipole (like the Earth’s) falls off with distance from the dipole as 1/r3. How do the two functions compare?

 

This is good news. While at first, the magnetic field is lower than the density, eventually we come to a point where the magnetic force will be stronger than the drag force for fixed velocity. (This makes sense, because some spacecraft use magnetic forces to orient themselves when they are well above the levels of appreciable atmospheric density.) Suddenly, this idea doesn’t seem so crazy.

The second, problem, though, is tougher. Remember buoyancy? Once we get up to about 34 km altitude, according to that graph, the air will be about half as dense – which means our balloon will need to take up twice as much volume in order to stay afloat. The higher up our spacecraft goes, the bigger than balloon has to be. Eventually our balloon is going to need to be kilometers in diameter, since we won’t yet be up to orbital speed and gravity will just pull the spacecraft down unless we keep our spacecraft buoyant. (This is why high-altitude balloons always eventually pop!)

Because our vehicle has to solve both problems simultaneously – staying afloat and accelerating – I don’t think it’s feasible to get a large satellite into orbit this way.

However, if we move to a size scale where some of the physics behave differently – say, if we make our spacecraft very small – then perhaps we won’t run into this problem with the balloon. A few years ago, one of the researchers in my old lab took a look at some of these very questions of drag and magnetic forces on tiny spacecraft, though not with the goal of launch in mind. But one could, theoretically, make tiny spacecraft capable of accelerating to high speed by interacting with a planetary magnetic field. One could also, theoretically, make spacecraft tiny enough to flutter down through an atmosphere unharmed. Combining and reversing these ideas would be an interesting long-term research challenge!

 

Posted in Concepts, Space | 9 Comments

First spacecraft from my graduate lab launched!

Just a quick note to share some exciting news: the first spacecraft to come out of my graduate research lab – Cornell University’s Space Systems Design Studio – launched with the SpaceX Falcon 1.1 debut yesterday. SpaceX says that the CUSat technology demonstrator vehicles deployed nominally. You can read more about the launch here. I did only a tiny bit of work for CUSat, but I know other students who did a lot more! Congrats to the CUSat team. It’s been a long wait.

The next launch out of my old stomping ground lab will be KickSat, going up on the next Falcon to carry supplies to the International Space Station.

Posted in Graduate school, Space | 5 Comments

The inkwash map

I have finally finished off a new map to share with everyone!

The inky islands

This is entire ink and ink washes, applied with both pens and brushes. It’s mostly black ink, with a bit of brick red for those cryptic labels.

These mountains are in a new style, too. Their shapes are more blocky and angular, and I provided all the relief with ink wash rather than hatching. The coastline also departs from my previous maps, where I favored a double line with a thicker landward line. Here, the line is no different from any other, but I drew in some icons for breakers and focused the washes on the water side of the line.

close-up

The labels have a sort of funny procedural story to them. They don’t consist of much; simply a few random scribbles with suggestions of ascenders, descenders, and diacritics. I always intended to do something tiny and random rather than making precise characters. What’s funny is that I let this map sit for months between when I finished with the black ink and when I sat down for the quarter hour it took to put in the labeling. In all previous cases, I’ve had something very careful in mind with my labels; this time, I went in wanting to scribble randomly on my map. In ink, that scribbling becomes permanent. (I can scrape off ink with an x-acto knife, but that leaves some slight damage on the paper and isn’t feasible on a large scale.) Eventually, I just had to bite the bullet and see what came out the other side of the process.

Then I could call the map done.

Posted in Art, Maps | 6 Comments