Fetch all available/listed NASA images of the day. Can be run through cron, executed by node.

nasa-img-of-the-day.js

var rss_url = 'http://www.nasa.gov/rss/dyn/lg_image_of_the_day.rss';
var directory = '?';

var FeedParser = require('feedparser'),
	request = require('request'),
	fs = require('fs'),
	path = require('path');

var feedparser = new FeedParser(),
	req = request(rss_url);

req.on('error', function(err) {
	throw err;
});
req.pipe(feedparser);

feedparser.on('error', function(err) {
	throw err;
});
feedparser.on('readable', function() {
	var stream = this,
		meta = this.meta,
		item;

	while (item = stream.read()) {
		var title = item.title,
			date = new Date(item.pubDate),
			enclosures = item.enclosures;

		if(enclosures != null) {
			enclosures.forEach(function(enc, i) {
				var enc_url = enc.url,
					fetch_req = request(enc_url),
					full_title = title + ' (#' + i + ')';

				fetch_req.on('error', function(err) {
					console.log('Could not fetch ' + full_title + ': ' + err);
				});
				fetch_req.on('response', function(res) {
					var datestring = date.toISOString().substring(0, 10);
					var original_filename = path.basename(enc_url);
					var filename = datestring + '_' + original_filename;

					var full_filename = path.join(directory, filename);
					if(fs.existsSync(full_filename)) {
						console.log("Didn't fetch " + full_title + "; the image did already exist");
					}
					else {
						var writeStream = fs.createWriteStream(full_filename);

						fetch_req.pipe(writeStream);
						fetch_req.on('end', function() {
							console.log('Fetched ' + full_title);
						});
					}
				});
			});
		}
	}
});

package.json

{
  "name": "nasa-image-of-the-day",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "author": "Simon Welker",
  "license": "MIT",
  "dependencies": {
    "feedparser": "^1.0.1",
    "request": "^2.55.0"
  }
}