Friday, July 27, 2012

"O! say can you see by the dawn's early light..."

LROC's most frequently asked question answered:LRO slewed 19° down-Sun allowing the illuminated side of the still standing American flag to be captured at the Apollo 17 landing site. LROC Narrow Angle Camera (NAC) observation M113751661L, LRO orbit 1897, November 25, 2009; 52.5 cm resolution, angle of incidence 56.73° from 44.87 kilometers [NASA/GSFC/Arizona State University].
Mark Robinson
Principal Investigator
Lunar Reconnaissance Orbiter Camera
Arizona State University

The most common questions to the LROC team before launch concerned what will we see at the Apollo sites? Will we see the Lunar Module descent stage and rovers? What about rover tracks, or the American flags? As we now know, the NAC images clearly show all of the above items (see links to earlier posts at the bottom). Personally I was a bit surprised that the flags survived the harsh ultraviolet light and temperatures of the lunar surface, but they did.

What they look like is another question (badly faded?). Much has been written about the Apollo flags, a comprehensive summary is available at the Apollo Lunar Surface Journal.

Charlie Duke captures John Young saluting the flag while jumping, (twice). A great demonstration of the lower gravity on the Moon. Apollo 16 Lunar Module (LM) Orion and the Lunar Roving Vehicle (LRV) are in the background. View the re-master original indexed at the Apollo 16 Lunar Surface Journal, HERE - MET: 120:25:42 - (AS17-113-18339) "He is off the ground about 1.45 seconds which, in the lunar gravity field, means that he launched himself at a velocity of about 1.17 m/s and reached a maximum height of 0.42 m. Although the suit and backpack weigh as much as he does, his total weight is only about 65 pounds (30 kg) and, to get this height, he only had to bend his knees slightly and then push up with his legs." Video Clip ( 3 min 21 sec 0.9 Mb RealVideo or 30 Mb MPEG ) [NASA].
The opening image was taken early in the mission, and is one of the best views of the American flag because the spacecraft was pointed towards the illuminated side of the flag, and Sun was low enough (56° incidence angle) such that distinct shadows were cast.

The flag was captured in this image of the Apollo 16 site with the spacecraft slewed 15° towards the Sun; the shadowed side of the flag is seen by LROC. NAC frame M175179080L, orbit 10950, November 6, 2011; native resolution 40.4 cm per pixel, angle of incidence 41.91° from 23.56 kilometers [NASA/GSFC/Arizona State University].

From the LROC images it is now certain that the American flags are still standing and casting shadows at all of the sites, except Apollo 11. Astronaut Buzz Aldrin reported that the flag was blown over by the exhaust from the ascent engine during liftoff of Apollo 11, and it looks like he was correct! The most convincing way to see that the flags are still there, is to view a time series of LROC images taken at different times of day, and watch the shadow circle the flag (see movie below; the flag is just above the LM descent stage).

Visit the full resolution NAC of the Apollo 16 site HERE. A full resolution version of the Apollo 12 time series is available HERE.

Explore all the Apollo sites on LROC's new Featured Sites webpage!

Related Posts:
Exploring the Apollo 17 Site
Apollo 11 Low Altitude
Apollo 12 Low Altitude
Apollo 14 Low Altitude
Apollo 15 Low Altitude
Apollo 16 Low Altitude North Ray Crater
Apollo 17 Low Altitude
Apollo 17 Low Altitude Shorty Crater


Anonymous said...

Just curious, has LROC found any of the impact sites of jettisoned LEM ascent modules?

Joel Raupe said...

Officially, no.

Samuel Lawrence at Arizona State assures me a long-anticipated and updated comprehensive list of cataloged and confirmed artifacts, cross-referenced with their observation and coordinates, and originally published April 5, 2010, will be updated later "this summer."

While totally unconfirmed so far, for our own part we suggest a strong "candidate site" for Apollo 12's Intrepid impact (3.6846°S, 21.2565°W), a "Dark Halo" candidate for Shepard's Apollo 14 LMAS (3.4171°S, 19.6380°W) and another "strong candidate" for Apollo 15's ascent stage (26.0372°N, 0.0879°E), as well.

We continue to search for Apollo 17's published impact, west of, on, or south of South Massif, but may be frustrated for reasons similar to the conditions we've encountered while searching for Kaguya's very well-documented and timed 2009 impact. Specifically, the most likely impact site for Kaguya seems to be on a steep slope, a south-facing crater wall. The easiest indicators of a fresh impact, if true, appear to have been subsequently covered by a landslide.

So, we eagerly await an updated "Lawrence List," and find the delays in going out on limb quite understandable.

Dr. Lawrence's original list, by the way, is still at the following link:

(We also incautiously staked a claim last December for having located the elusive, historic and very small Luna 9 vehicle, and we're prepared to stand by that, until humiliated.)

Anonymous said...

Good info. Thanks!