October 20, 2009
Hop, Skip & a Bounce & a Bounce & a Bounce & a Bounce & a Bounce & a Bounce
image from LROC Image Browser, NASA/ASU
The Narrow Angle Camera (NAC) of the Lunar Reconnaissance Orbiter is showing us the Moon at a scale consistent with everyday human experience. The long boulder track seen here is about 8 m wide - about the length of two cars parked in the street. The first bounce pit (at bottom left of left frame) is on the side of a fresh 440 m wide crater out of the image to the bottom right. Apparently the boulder (top right on right-most frame) was ejected during the formation of the crater and bounced roughly 75 times, traveling about 2 km before running out of energy. The long distance is because the 440 m crater is near the rim of the 14 km wide Metius B, so the boulder bounced down that crater's wall until it reached the floor. Notice that each bounce depression is complex, being elongated and often preceded by a circular depression, and sometimes further extended in the downslope direction. The boulder itself is about 12 m long and 8 m wide so it may have tumbled onto its small end and then fell over onto its 12 m long side, perhaps sliding a little, before it took its next hop. Look closely at the full resolution scene and you'll find many other trails, including a narrower but longer one.
Not a detail, just a plea to the LROC team: Please show us more of the Wide Angle Camera images!
Rükl plate 68
Yesterday's LPOD: A Bedtime Story
Tomorrow's LPOD: Not the Moon