Saturday, December 3, 2011

"Boy, that sure looks like Luna 9!"

Fig. 1  Idealized Google Earth icon of Luna 9, the first soft-landing on the Moon (the first soft-landing anywhere other than Earth), February 3, 1966. The cartoon Russian spacecraft is pinpointed more than 30 kilometers northeast (8.0°N, 296.0°E) of an 'official' landing site (7.08°N, 295.63°E) because investigators say the 'official' coordinates place the lander well beyond the eastern rise, at left on the horizon above. That location doesn't appear to match the landscape seen in the panoramas returned to Earth. The object identified as a likely candidate, at 7.153°N, 295.630°, is less than 2.8 km north of the official coordinates, but at a notably higher elevation on that same rize, perhaps where fewer obstructions are to be found on the local horizon [NASA/USGS/JAXA/Google].
Joel Raupe
Lunar Pioneer

The problems encountered by the Russian Federation after the launch of Fobos-Grunt on November 9, when compared with the apparent ease NASA is experiencing, thus far, in getting Curiosity through the present Martian launch window, might tempt fools to dismiss Russia's interplanetary skill. Russian morale might be threatened but we're reminded yet again that Space is relentlessly intolerant of cutting corners or under-funding. The Great Galactic Ghoul, that cosmic gremlin supposedly spoiling to ruin Mars and Moon missions alike, spends most of its time here on Earth.

Off-planet, when Institutional Memory is applied efficiently, the Russians are a match for anyone.

Friday, December 2 is the 40th Anniversary of the first soft-landing on Mars, and Russia's Mars 3 lander was successful, though the lander operated on the surface only 20 seconds, back in 1971. Saturday, December 3 is the 12th Anniversary of the loss of America's Mars Polar Lander in 1999. Thus, the success of Curiosity is by no means a sure thing. When space exploration begins to look too easy disaster waits patiently at the door.

A planned Russian return to the lunar
surface may ultimately benefit from a post-
Fobos-Grunt shakeout
The first vehicle soft-landed on the Moon (and the last one landed there, a decade later) were strictly Made in Russia. Embarrassing and often tragic, spectacular failure also often fuels political will, without which governments accomplish nothing.  After a latter-day purge of Russia's unmanned mission contractor NPO Lavochkin, the legacy of Fobos-Grunt may help guarantee eventual success for Luna-Grunt and the other lunar missions Russia has in the works.

If all goes well, beginning next month, the United States will support five spacecraft exploring the Moon simultaneously, the most prominent among them the record-smashing LRO. Following decades of a near total neglect of its hard-won and expensive lunar legacy, America owes a revival of interest in Earth's Moon directly to the loss of Columbia in 2003.

An early priority for LRO was a survey of human artifacts on the Moon. Delivering spectacularly on that assignment were Mark Robinson, principle investigator for the Lunar Reconnaissance Orbiter Camera (LROC), together with his team at Arizona State University. Their most newsworthy success, quite naturally, were many high resolution history-making photographs of the relics and footprints from the Apollo program.

Fig. 2  Planitia Descentus - Latin for Plain of Descent, a human distinction for an otherwise indistinct borderland along the western edge of Oceanus Procellarum, where Luna 9 came to a tilted stop February 3, 1966.  The yellow dot on the rise at center bottom on both maps makes the location of an object that could be Luna 9. These comparative maps of the same 14,300 square kilometer area (centered near 8.48°N, 64.47°W) are (top) LROC WAC DTM  juxtaposed with (bottom) LROC WAC mosaic, each from LROC/ASU QuickMap (250 m/pp resolution). [NASA/GSFC/Arizona State University].
A steady stream of LROC Narrow Angle Camera (NAC) views were released during the LRO Nominal Mission revisiting the remains of a host of U.S. and Soviet spacecraft, both impact craters and the intact sentinel spacecraft themselves following hundreds of lunar days and nights. Each of these Featured Images released by LROC has fired the imagination while calibrating and confirming some very old, often incomplete sets of data.

Finding Lunokhod 1 (38.316°N, 324.996°E), for example, was an overdue accomplishment. It was the first robotic rover on another world, equipped with a laser range reflector that had eluded detection for decades. Its addition to the passive network of reflectors set up by Apollo 11, 14 and 15, together with its French-built twin on Lunokhod 2 allowed the measuring of the Earth-Moon distance to within 3 mm, the missing tolerance needed to test whether a range of physical laws were exclusive to our neighborhood in the universe.

A compendium of LRO's definitive findings, LROC Coordinates of Robotic Spacecraft, put together by Samuel Lawrence at ASU, was released April 5, 2010.

Though the list has not been updated since, it's still spectacular. For the first time, for example, anyone with an Internet connection can see precisely what happened when the third stage of the Saturn V that pushed Apollo 13 around the Moon impacted with the lunar surface. And planetary scientists have a precise date on a fresh impact crater on the Moon, as well; a standard useful for dating optical maturity and space weathering. We no longer have to imagine if the footprints are still there and decades of doubters can precisely see for themselves how the astronaut's surface photography matches the landscapes as seen only 45 (and more recently 25) kilometers away.

Still, the table put together by Lawrence can't yet be comprehensive.

A search for the place where Luna 2 became the first man-made object to impact another world in 1959, for example, is fraught with uncertainty. Those official coordinates are necessarily wide of mark, if only because the precise location of the Moon itself, and its surface, would never again be less well understood than before the Russian measured the time of impact for Luna 2.

A search for Luna 2 using those rounded-off coordinates brings the investigator west of Autolycus, to a 22 square kilometer area where there are at least two, perhaps three, fresh craters with the proper wispy signatures. One of them shows signs of a unique debris field, perhaps dotted with a cluster of the impact-resistant Soviet flag-engraved metal balls reportedly loaded on Luna-2. A surface expedition will be needed, in other words. As amazing as it is, however, even the LROC Narrow Angle Cameras have their limits.

At the very edge of those limits is Luna 9, the 99 kg.lander the Soviets succeeded in soft-landing on the Moon on February 3, 1966. In Multiple NAC footprints covering the target area uploaded to the Planetary Data System, even by April 2010, it was easy to see the LROC team had already earnestly tried to find that historic relic. But Luna 9 wasn't on the list put together by Lawrence.

Fig. 3  A closer look at the Plain of Descent.  The rectangle matches a 2.5 km-wide cross-section of LROC NAC observation M137970706R, the area seen in Figure 6a, below. The small white dot marks a spot less than a kilometer south of the rectangle, the official Luna 9 landing site, and the white dot inside the rectangle marks the location of an "object of interest," something that seems to be a Luna 9, in the two NAC observations detailed below.  The 'mid-morning' view above is a 41-km-wide field of view taken from LROC Wide Angle Camera (WAC) observation M160376850C (604 nm), LRO orbit 8769, May 18, 2011; incidence angle 55.42° with a resolution of 57.55 meters per pixel, from an altitude of 40.49 km [NASA/GSFC/Arizona State University].

As noted expert on lunar artifacts Phil Stooke of the University of Western Ontario put it, finding the very first vehicle soft-landed on the Moon was "problematic," even with the proven sensitivity of the twin LROC Narrow Angle Cameras. 

There is lingering dispute about the true landing site, though the central difficulty in finding Luna 9 is probably the small spacecraft's low profile. Its instrument housing is barely at the half-meter limit to the LROC NAC Nominal Mission resolution. And, because discussing Luna 9 without seeing its mission in the context of the Cold War would be incomplete, a brief comparison with Surveyor, its very real competition, is necessary.

The Russians beat Americans to the Moon in 1966 by only five months. Samuel Lawrence had already written up and released LROC's first views of "Surveyor 1 - America's first soft lunar landing," on September 30, 2009. That observation (M102443995L) swept up the first U.S. lander very early in LRO's Commissioning phase, in orbit 272, when LRO was still flying at twice its Nominal mission altitude, from 102.4 km overhead. That survey of the floor of Flamsteed P was photographed at less than half of the planned LROC NAC resolution; at 1.08 meters per pixel, the Surveyor 1 tripod in profile was barely visible, identifiable mainly in its long shadow at local sunset.The Surveyor design featured a central mast with square solar panels at the top, standing high like a flag. That aided in identifying all five of the successful Surveyor landers, right they sat. 

Unlike its Google Earth icon, seen in Fig. 1, Luna 9 was not standing like an egg, balanced on one hemisphere. After its landing and activation Luna 9 was at tilted, and from slight changes in the background seen in its five photographic panoramas we can tell Luna 9 shifted slightly after deployment.

Fig. 4  Simulated oblique view west by northwest over the area of interest from a point 28 km over the western Oceanus Procellarum. After years of deconstructing the five panoramas captured and returned to Earth by Luna 9, many reliable experts have come to doubt the accuracy of the official landing site (coordinates on the left, at "-1310 m" elevation).  Some believe Luna 9 must have landed somewhere in the plain to the north (on the right, marked "-1640 m").  If the object detailed in Figures 5 and 6 below is Luna 9 then the lander came to rest at a point less than three kilometers and almost due north of the official coordinates ("-1170 m"), and at least 140 meters higher in elevation.  After studying the LROC WAC Digital Terrain Model of the area (Fig. 2) the hills, contiguous with other features surrounding the Plain of Descent, appear to be the highly degraded rim of an ancient, mostly buried crater.  -Image created using ILIADS application, developed by NASA's LMMP project; photography from LROC WAC Global Mosaic with elevations from LOLA altimetry (v.2). [NASA/GSFC/ARC/LMMP/ASU].
The low profile and squat, efficient design of Luna 9 have made it difficult to definitively locate, either somewhere in the expansive plain to the north or near the official position somewhere on a 500 meter high hill, nor on their slopes. All of the area was extensively photographed from LRO, from high altitudes and low, under high Sun and low Sun, with LRO rolled and looking down from directly overhead. If the little vehicle has been captured (which seems certain) what would distinguish its egg shape from thousands of boulders more or less the same size?

It's a safe bet Samuel Lawrence and others on the LROC team encountered this difficulty head-on, with the determination and resourcefulness of a Cold War photo-analyst pouring over U2 photographs of Cuban missile sites. 

In fact, it would be the height of presumption on our part to claim to have done anything more than retraced their steps. It's impossible to believe a candidate object we stumbled on, within their choices of photographic session, hasn't already been considered or scratched off the list. Were it not for something that may turn out to be simply an artifact of digital compression we wouldn't take another look.

Let's just say, "boy, that sure looks like Luna 9!"

What follows are two sets of images, selected from two separate LROC NAC observations, focused on an "object of interest" at sunrise (Figures 5a and 5b), when the Sun was less than 5 degrees over the east horizon, when long shadows allow for depth perception, and then (in Figures 6a - 6d) where, at less than 8° north of the equator, the Sun was high overhead and depth perception gives way to a search for subtle variations in brightness or optical maturity.

Fig. 5a   The full 2.5 kilometer-wide field from LROC NAC M132071202L orbit 4597, June 25, 2010; with resolution greatly reduced from the original 0.48 meter per pixel resolution captured from 40.49 km altitude, incidence angle 85.57°. The yellow rectangle is the area shown at full resolution in Fig. 5b, immediately below. The yellow dot is our "object of interest," so to speak, indicated with an arrow in at full resolution below. The object certainly casts a shadow, as anything with a profile would when caught in naked morning sunshine on the Moon. It is also seemingly brighter than other similarly sized objects in the roughly 238 meter-wide field of view seen below.  [NASA/GSFC/Arizona State University].
Fig. 5b  Full resolution, and very non-definitive rendition of the Object of Interest, again, from LROC NAC M132071202L The object appears to be situated within the west slope of a 10 meter crater, whose interior is very darkened with shadow. Since Luna 9 arrived on the Moon not long after local sunrise, this doesn't help identify the object as Luna 9. The larger, similarly bright object to the southwest is too large to be Luna 9, but its size and location relative to the object of interest makes a case for it being part of the larger lander bus [NASA/GSFC/Arizona State University].
On the 500 meter hills, south of "the plain of descent," under an afternoon Sun:

Fig. 6a  Backing away once again, shifting perspective slightly to the west, with the Sun nearly overhead, this is the field of view within the rectangle back in Fig 3, and slightly west, overlapping the area in Fig. 5a, another 2.5 km-wide area taken this time from LROC NAC M137970706R, orbit 5466, September 1, 2010, from 45.57 km in altitude (incidence angle 29.64°). The area in the white rectangle is the field of view enlarged in Fig. 6b, immediately below [NASA/GSFC/Arizona Sate University].
Fig. 6b  At 40 percent of their original resolution, line 14775 to 15556 by sample 3964 - 4544 from M137970706R. (The dim dark line is an artifact "junction" between line 15000 and 15001). And, like a Russian Doll, the square box above is the roughly 290 meter-wide field of view seen at 100 percent of the original observation's 0.5 meter per pixel resolution seen in Fig. 6c, immediately below [NASA/GSFC/Arizona State University].
Fig. 6c At full resolution, lines 15001 - 15580 by sample 3964 - 4543 from LROC NAC M137970706R. Compare this with Fig. 5b, above and, once again, what is seen under differing lighting conditions on the Moon is clear. When happening upon this candidate object under a high Sun, something catches the eye [NASA/GSFC/Arizona State University].
Fig. 6d  Taking  LROC NAC M137970706R  well beyond its true limit of resolution we stumble upon what might be Luna 9, resting on the west interior slope of a shallow 10 meter crater, perhaps even afterwards sliding slightly between photographic panoramas, February 3, 1966. Under an early afternoon Sun, after being enlarged 400 percent with a super-sampling algorithm, what appear faintly as three of the spacecraft's four instrument-shielding petals (the fourth presumably in its shadow) somehow popped out from the background. No intentional fudging was done to the original brute-force enlargement (See Fig. 7) [NASA/GSFC/Arizona State University].
Fig. 7 A simple enlargement to 400 percent of the half-meter per pixel resolution native to LROC NAC observation M137970706R turned up this object, certainly an oddity if it is not Luna 9. As demonstrated in the hackneyed animated image (Fig. 6d), the object meets the profile, is barely less than 3 kilometers due north of its official landing site, about 140 meters higher in elevation, on a broader slope with presumably less obstructed horizon.

Fig. 8 The view south from Luna 9, February 3, 1966.

Using the popular open-source program Orbital Simulator, "reseferina1" created this interesting simulation of the Luna 9 mission in 1966. Though fun, it too, unfortunately, made the thing look far too easy. The originating YouTube page is HERE.


Phil Stooke said...

Hi - nice article! I am a bit dubious about this because it sits in a small crater, which I think would be obvious in the panoramas.

Phil Stooke

Joel Raupe said...

Thanks, so much Phil. The compliment means a lot coming from you. I know you've mapped the site, based on the panoramas, and I may not have communicated how dubious I am about this "candidate object."

I would think particularly the west wall of that shallow crater would be obvious, too. I can think of a number of ways why it would be more obvious from a height than from the POV of the Luna 9 camera.

I wonder where Samuel Lawrence has marked candidate objects, and yourself, if you've had the time. I wish he's update that list they published in April 2010! Guess they figure these sites won't be going anywhere.

Amazing how elusive some of the impact sites have proven to be. The best site I've found for Kaguya, for example looks like a subsequent minor landslide covered the expected evidence.

Again, thanks for the comment. Best wishes!