Image of one wheel from the Mars Exploration Rovers.
NASA
<a rel="nofollow" class="external text" href="https://mars.nasa.gov/mer/mission/technology/autonomous-planetary-mobility/">In-situ Exploration and Sample Return: Autonomous Planetary Mobility</a> <span style="font-size: 0.95em; font-weight: bold; color:#555; position: relative;">(in en)</span>. <i>Mars Exploration Rovers</i>. NASA. Retrieved on <span class="mw-formatted-date" title="2020-04-08">2020-04-08</span>.