Saturday, September 7, 2013

LADEE legacies

LADEE approaches lunar orbit insertion
In planning since 2008, LADEE's reason-for-being emerged from mapping science goals believed essential before any permanent manned presence on the Moon's surface could begin. Fortunately, like LRO, LCROSS and GRAIL, planning and development were well underway and within budget when Congress eventually scrubbed the Constellation brand and manned Altair lander [NASA].
Like "The Blind Men and the Elephant" the most important moving part of many riding along with LADEE to the Moon very much depends on your personal perspective.

What might seem a low-priority mission, accompanied by an appropriate degree of "hype," and has modest fundamental goals under the banner of experimental modular designs and revolutionary high speed communications, - only a 100 day science mission, LADEE has been in development for more than five years. The advanced vehicle also carries with it hopes of some that go back nine times that period, covering a lot of political ground and many changes, even over the relatively short time since its framing and approval.

Gene Cernan's Dusty Spacesuit
Gene Cernan (by Harrison Schmitt) at the close-out of the third and final EVA of Apollo 17, and the last manned visit to the Moon in December 1972. The commander's spacesuit is blackened by exceeding fine lunar dust, more than just a problem of appearances, a real hazard that might have caused hatch and spacesuit seals to fail on a longer surface mission. Constellation planners understood they needed to get a handle on mitigating the hazard posed by omnipresent dust while also gaining an better understanding of the dynamics of a primal airless Moon and its surface before humans return to stay [NASA/JSC].
Few watching the LADEE/Minotaur V launch, critical for Orbital Sciences Corporation, from Wallops Island, are likely to be reminded that the mission owes its existence to the catastrophic loss of Space Shuttle Challenger ten years ago. But it is possible to appreciate the things NASA logically wants emphasized without forgetting LADEE is the beginning of the end of the defunct Constellation program that so many wanted dead and buried in 2009.

LADEE is the last of the unmanned precursor missions once believed essential before "extended human activity" on the Moon could begin. The absolutely remarkable Lunar Reconnaissance Orbiter (LRO) will likely still be orbiting the Moon for a few years after LADEE's mission-terminating guided impact a few months from now, but none of these 21st century American unmanned lunar missions are likely to have have occurred before today without the initial political will put in motion after the report of the Challenger Accident Investigation Board (CAIB).

LRO, LCROSS, GRAIL and now LADEE each owe their reason for being to the loss of a second Space Shuttle and crew in 2003.

LADEE Slides (LEAG 2011 Lunar Exosphere Model (After Halekas))
Very simple schematic of the lunar exosphere. The Moon's surface turned out to be a very dynamic place, after all, with water and exotic metals and volatiles trapped in permanent shadow and also hiding in plain sight [Halekas/LEAG/NASA].
If you've seen the movie footage of Neil Armstrong immediately after setting that first boot on the Moon, backing away from the ladder tethered to the spacecraft then you may have guessed there once was real fear that he might just suddenly disappear in a bog of dust.

Such concern had mostly been dispelled by July 1969, though, after none of the successful unmanned Surveyor landers had encountered anything other than a hard-packed lunar surface. And yet the Moon was correctly presumed to be a very dusty place, constantly "gardened" by micrometeorites (and some not so micro) together with energetic cosmic and solar radiation. Without direct samples, however, no one correctly guessed just how "fine" the dusty powder on the lunar surface could be.

By the time Gene Cernan climbed back into the Apollo 17 lunar module in late 1972 at the end of the program another hazard from this dust had become apparent instead. Rather than sinking into feathery banks of fluffy snowbanks astronauts had to deal instead with a film of electrostatic-charged, clinging and microscopic glassy razor blades. It smelled like gun powder and got into everything, and seemed impossible to clean.

The dark dust of the Moon's immediate surface threatened hatch seals, it scared and tore into spacesuits and, following EVA close-outs became lodged in every conceivable place on an astronaut's body, including up their noses, in their lungs and also lingering in their softest places.

Clearly, "dust mitigation," by then long acknowledged as a real mission and health hazard, came forward as a priority science goal when before new lunar surface expeditions could be carried out. It is accepted as a similar threat to manned travel to Mars, and to the asteroids.

All models of what has become known as a "dynamic" rather than "static" lunar surface include production and trapping of volatile compounds once thought essentially non-existent on the Moon. The speed of this production, it's true dynamics, badly need to be studied before we can return to the Moon with impunity.

Every time an unmanned spacecraft (or a manned lunar module) has landed or taken off from the Moon it's certain some of the dust propelled away by exhaust reaches escape velocity. A larger part of this spiny cloud is put into orbit or on a ballistic path carrying these particles all over the lunar surface. LADEE is designed to establish some natural baseline for this dust before humans start stirring things up. The impact of spacecraft is comparable to the occasional larger natural impact, but hot gas exhaust and its effects is something new.

Painted On Procellarum
The delicate bright dust lanes of the Reiner Gamma "swirl albedo" phenomena, stretching at least 550 km southwest from the dormant volcanic Marius domes to the western frontier of Oceanus Procellarum. Seen here in an LROC WAC mosaic from 2010 under early morning shadows. Detailed laser altimetry confirms little to no topographic component, though it does closely correlate with a well-mapped anomalous crustal magnetic field that must be older than exposure to the Sun and space weathering would allow the surface here to remain so bright. Migration of dust, alternately charged and discharged, dislodged by micro-bombardment is alternately attracted and repelled, here, by the local magnetic field lines, keeping the new dust constantly renewed and gathered no more than a meter or so deep [NASA/GSFC/Arizona State University].
Whether or not this was really a guesstimate or hard science, by the time Congress seriously committed to return to the Moon to stay investigators had acknowledged that a kind of primal state existed there that was worth scientific study for its own sake, before human engaged in any "extended activity." And herein is the compelling interest for funding the LADEE mission. It's one way of discovering the state of the lunar exosphere, its dynamics in and out of Earth's extended magnetic field, under a traveling solar incidence, and through a good sampling of lunar days and nights before things inevitably get busy.

The hyperfast laser-based communications and modular spacecraft design for LADEE will be much talked about in reports about this mission, over the next few days and months. That's "all good," as they say, but it might be worth it to also remember the mission's origins going back before Surveyor or Apollo and also offer at least some thanks to the crew of Columbia. We owe the recent renewed short burst in lunar exploration and our added knowledge of the Moon directly to the loss of that spacecraft and crew.

Lunar Horizon Glow from Clementine (1994)
Another lunar mission (and one of only two American missions to the Moon between 1972 and 2009) was also justified as a test platform for new technologies. Now "lost and gone forever," Clementine (1994) spent a year in lunar orbit operated by both NASA and the U.S. Department of Defense. Here Clementine's star-tracking camera finally definitively photographed the "horizon glow" caught previously in the lunar night from the surface by Surveyor 7 and described by Apollo astronauts in lunar orbit twenty years before. This is the phenomena, believed to be back-lit lunar dust, that LADEE is designed to directly sample [NASA/DOD].
And whenever humans eventually return to the Moon for their inevitable extended stay, they will owe much of their preparation to that spacecraft and crew.

Related Posts:
LADEE Prelaunch Mission Briefing (September 6, 2013)
ESA prepares for LADEE (July 31, 2013)
LADEE arrives at Wallops Island (June 5, 2013)
LADEE ready to baseline dusty lunar exosphere (June 5, 2013)
First laser comm system ready for launch on LADEE (March 16, 2013)
LADEE project manager update (February 6, 2013)
The Mona Lisa test for LADEE communications (January 21, 2013)
Toxicity of lunar dust (July 2, 2012)
Expectations for the LADEE LDEX (March 23, 2012)
The Dust Management Project (August 9, 2010)
LADEE architecture and mission design (July 6, 2010)
DesertRatS testing electrodynamic dust shield (July 5, 2010)
Dust transport and its importance in the origin of lunar swirls (February 21, 2010)
Dust accumulation on Apollo laser reflectors may indicate a surprisingly fast and
more dynamic lunar exosphere
(February 16, 2010)
NASA applies low cost lessons to LADEE (January 18, 2010)
Nanotech advances in lunar dust mitigation (August 19, 2009)
Moon dust hazard influenced by Sun's elevation (April 17, 2009)
LADEE launch by Orbital from Wallops Island (April 14, 2009)
Understanding the activation and solution properties of lunar dust
for future lunar habitation
(March 2, 2009)
Respiratory toxicity of lunar highland dust (January 19, 2009)
Toxicological effects of moon dust (June 25, 2008)
Moon dust and duct tape (April 22, 2008)


kvo said...

Hey, great blog! I noticed your Gene Cernan photo is linking to AS17-145-22204HR.jpg instead of AS17-145-22224HR.jpg.

Joel Raupe said...

Thanks, kvo. Fixed it! Much appreciated!