<?xml version='1.0' encoding='utf-8'?>
<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>E. F. Helin</dc:contributor>
  <dc:contributor>S. L. Gillett</dc:contributor>
  <dc:creator>Eugene Merle Shoemaker</dc:creator>
  <dc:date>1976</dc:date>
  <dc:description>&lt;p&gt;The population of Apollo, Amor and Mars crossing asteroids is studied. With the 18-inch Schmidt camera of the Hale Observatories at Mt. Palomar, four new planet crossing asteroids were discovered. &lt;br&gt;A formal theory relating the probability of discovery of asteroid of a given orbital class to condition of search has been developed. &lt;br&gt;From the estimated populations the flux of the Apollo objects to magnitude 18 near the Earth is of the order of (0.4 &lt;span&gt;±&lt;/span&gt; 0.2) 10&lt;sup&gt;-14&lt;/sup&gt; km&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;. During 3.3 b.y. this flux produces an estimated 60 &lt;span&gt;± &lt;/span&gt;20 craters of 10 km in diameter and larger per 10&lt;sup&gt;6&lt;/sup&gt; km&lt;sup&gt;2&lt;/sup&gt; on the Moon. This number seems to be consistent with the observed crater densities on 3. 3 b.y. old mare surfaces in the eastern Oceanus Procellarum and Mare lmbrium. &lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:language>en</dc:language>
  <dc:publisher>Sapienza Universita</dc:publisher>
  <dc:title>Populations of the planet-crossing asteroids</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>