NASA Shoots for Mach 10 The agency plans to prove that the 40-year-old dream of "hypersonic" flight -- using air-breathing engines to reach speeds above 3,800 mph is a reality. &lt;FONT face="verdana,MS Sans Serif,arial,helvetica" size="-2"\ color="#666666"&gt;&lt;B&gt; -The Washington Post&lt;/B&gt;&lt;/FONT&gt;