Mapping Vesta, or My Descent into Irrational Unease

8 February 2013 by Troy McConaghy, posted in Astronomy

Last week, I signed up with a citizen science project to map the asteroid Vesta. Here are my first impressions.

The Vesta Mappers Interface

The Vesta Mappers interface. Click it to see a full-size version.

The Dawn spacecraft orbited Vesta from July 2011 until September 2012. It captured lots of images of the surface. 6192 of those images were put into a database for the "Vesta Mappers" project. You can see one of those images above. The idea is to get lots of people to mark the craters and other features, with the goal of making a map. Below you can see what I marked.

A Vesta image with markings

(Click to see a full-size version.)

It's exciting to be one of the first people to see close-up images of the surface of Vesta. Unlike the Moon, most of the big craters and ridges don't have names yet. (Some do.)

The experience is like I got a pile of random photos from someone's crazy vacation, but they're out of order, most are missing, and there's nobody to tell you how they relate to each other. Still, it's pretty cool.

One of my first impressions is surprise: I had no idea that there could be such variety on the surface of Vesta. I mean, it's an asteroid! There's no wind, no rain. And yet… How did it get all these weird features?

Sharp ridge

A sharp-edged ridge. The rim of a giant crater?

Crater chain maybe?

A crater chain? Or what?

Sinuous gully?

Is that a sinuous gully in the lower left corner?

A ridge with downhill flows?

A ridge with downhill flows?

The main activity is marking craters: you click on the center, drag to the edge, and let go. If it's off a bit, you can adjust the center, or you can delete it and try again. It's straightforward. sometimes the craters aren't completely round, but most are.

You don't have to identify all the craters, just the bigger ones. It won't let you draw a circle smaller than a certain size.

There's a checkbox to check if "Image has misshapen [craters]" and you can also mark a crater (feature) as an "odd shaped feature".

Sometimes something looks vaguely circular, but is it an impact crater?

Other Features

Then there are the other features you can mark…

  • Light albedo feature
  • Dark albedo feature
  • Boulder field
  • Bullseye (concentric) crater
  • Crater chain
  • Odd shaped feature
  • Odd albedo feature
  • Unknown

They provide a tutorial and a "Surface Features Glossary" to explain what those mean.

You can also check a box if the "Image has crests or troughs." That's fairly easy to do. Sometimes I wonder if a crest is just part of a huge crater that won't fit in one image.

I look for boulders. I really do. But I don't think I've ever found one. There are lots of tiny craters. In principle, you can tell the difference between a tiny crater and a boulder: the light/dark sides are reversed on boulders.

Sometimes a linear feature might be a "crater chain" but I always wonder if that's what it is. Maybe it's just a crack full of regolith? Sometimes crater chains have their craters so close together that they look like a length of rope.

You can mark a feature as "unknown" but it's only for marking single points, not linear things. Sometimes I mark the linear things with a bunch of "unknown" markers. I don't know if that's against the rules.

How's the Project Going?

I wish there was more feedback on what's going on with the project overall. We do get some overall numbers, and there's a forum with some postings, but I wish I had a better sense of the big picture. How many others are mapping Vesta right now? How many images were examined in the last day? Can I see an overall map, or 3D model of Vesta, indicating the areas that have been examined, and the areas that still remain?

Here are some of the overall statistics as of February 7, 2013:

Total Vesta images in database: 6192

Total Vesta images left: 4830

TroyMc's images: 35

I'm pretty sure I've marked more than 35 images! Maybe twice that.

Sometimes I see the same image a second time, or even a third time. Why?

Maybe my web browser's plugins are deleting cookies, so it can't remember which images I've seen before? I tried a different browser with no plugins. But I continued to see repeats.

I noticed that some images are of the same general area, but shifted or rotated. I guess that might account for some of the "repeat" images.

I know they sometimes show standard test images, to see if I mark things similar to an expert. Do they also sometimes show non-test images more than once to the same person? I don't know. I suppose they could do that to test for consistency.

If I'm not consistent, do I get punished? Is that why I keep seeing the same images over and over again? Is it a form of slow torture to scare away the inconsistent people?

Is one of the scientists or developers trying to encourage me to quit? If so, why? So they don't have to spread credit too thin? Because they don't trust amateurs?

It's not like there's a shortage of images! Or that's what they say. Maybe it's all a hoax and I've really been looking at images from the asteroid Eros? (I wouldn't know.)

I've read about psychological experiments where they tell the participants that they're studying one thing, but they're really studying something else.

And then there's the plot twist in Ender's Game, the novel by Orson Scott Card. I dare not say anything more.

Suggested Further Reading and Viewing

JPL's official Dawn mission website.

Vesta Mappers is a CosmoQuest project. CosmoQuest got started with a similar project to map craters on the moon.

Image Sources

The images of Vesta are courtesy of CosmoQuest and NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

About this Blog

Outer Spacing is a blog about space exploration and development. It's written by Troy McConaghy (@TroyMc on Twitter).


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