Saturday, September 15, 2012

Corrected close-ups

An oblong boulder left its distinctive impression on the gentle slope of a small crater near the center of Mare Serenitatis (24.64825°N, 18.85852°W). LRO was only 23 km above the Moon's nearside surface when this 31 cm resolution image was captured; LROC NAC M168081909R  orbit 9904, August 15, 2011. Angle of incidence 46.75° [NASA/GSFC/Arizona State University].
Nearly a year has gone by since the record-smashing Lunar Reconnaissance Orbiter had its orbital periapsis reduced dramatically, ahead of having its orbit brought up to a longer duration polar orbit above 100 km. In that time the LROC team at Arizona State University captured a catalog of dramatic close-ups, among these quick surveys of most of the Apollo landing sites of unprecedented clarity. Quite a number of pictures of less interest to the general public were captured as well, as LRO swept down over the Moon's nearside barely 20 km overhead.

Though the Clementine platform and the optically blind Lunar Prospector both completed their missions before the close of the last century (and the Apollo surface experiments were switched off in 1977) new research based on data collected from those efforts still regularly appears in the science journals. It's reasonable to expect new breakthroughs will continue to appear long after the LRO mission is completed, as well.

We are still threading through thousands of LROC Narrow Angle Camera close-ups from late in the summer of 2011, teasing images out while accounting for the distortions in the raw data that arise from the higher-speed with which LRO encountered its surface targets during those low passes.

In appearance much like driveway gravel, these boulders at the bottom of the cobra-head formation of a prominent sinuous rille in the Vera-Prinz region of Oceanus Procellarum would dwarf most houses. By far, the largest of the boulders (26.3353°N, 43.71077°W), isolated at upper right, is 28 meters wide. Full 41 cm resolution mosaic of LROC NAC frames M168488930L spacecraft orbit 9964, August 20, 2011; angle of incidence 43.79° from 26.43 km [NASA/GSFC/Arizona State University].
Belated corrections - Like the Moon, like the geological rate of change in the data in those vast catalogs, many of the posts appearing here have staying power!

Because of a busy season near the end of 2011, not long after the first bulk publication of many of these dramatic close-ups, in the LROC Planetary Data System release of December 15, 2011, we grabbed a quick look at a few of them and failed to return afterward to properly re-sample them.

Even backed away and resampled to 4 meters resolution, revealing the boulder field's location on the floor of the Vera formation (26.32°N, 316.28°E), the cobra head of a sinuous rille in Oceanus Procellarum, the level of detail visible in this LROC NAC frame is remarkable [NASA/GSFC/Arizona State University].
Uncorrected, these images first appeared here in a series of posts in late December, and having had the error pointed out nine months later, right about the time of our 3000th post since 2006, perhaps we can find time over the course of the remainder of our lives to correct all the other embarrassing errors also.

Life is short, but the "inconstant Moon" is just about eternal.

Context is nearly a necessity when presenting LROC NAC derivative imagery. Vera is demonstrated in this simulated perspective from NASA's ILIADS application to be more than merely the cobra-head of a sinuous rille. It appears to be a cobra-head within a cobra-head, emerging as many similar formation on the Moon do, from beyond the rim of a crater that, at some point after its formation, was inundated by fresh melt. Another example is Plato. Perhaps Prinz, now a nearly buried ghost crater, was flooded twice [NASA/GSFC/LMMP/Arizona State University].

1 comment:

Commerce Telecom said...

Hi, interesting post. I have been wondering about this topic, so thanks for posting. I’ll definitely be subscribing to your site. Keep up the good posts.