Conversations with Astronauts

Conversation between Harrison Schmidt, Brian J. O’Brien, and Clive Neal June 2019

  • Harrison Hagan "Jack" Schmitt is an American geologist, retired NASA astronaut, university professor, former U.S. senator from New Mexico, and, as a crew member of Apollo 17, the most recent living person to have walked on the Moon.

  • Professor Clive Neal - lunar research in lunar petrology and lunar geophysics.

  • (Prof.) Brian J. O'Brien - NASA Principal Investigator, Lunar Dust Expert

From: Clive Neal 
Sent: May 21, 2019 9:09 AM 
To: Lunar-L 
Subject: Moon Dust 

Interesting article on about Moon Dust:
See also

Clive R. Neal
Dept. Civil & Env. Eng. & Earth Sciences
University of Notre Dame, USA

From: Harrison Schmitt
Sent: Wednesday, 22 May 2019 5:22 AM
To: Clive R. Neal
Subject: Re: Moon Dust

Thanks, Clive.

As I, Larry Taylor, and many others have often said in many venues, the less than 100 micron dust that makes up about half of the lunar regolith has special physical (fractal shapes, nano-phase iron ) and chemical (unsatisfied electron bonds) characteristics; however, I know of no reason to consider this dust as one of the primary risks of operating on or settling the Moon that has no known means of addressing and managing. Funding and managing the return of the United States to the lunar surface constitutes a much greater risk than dust, absent the proven management environment created for Apollo.

 That said, protecting humans and equipment from any adverse characteristics of lunar dust constitutes clear and addressable engineering and operational approaches, many of which play forward to Mars:
1.         Design pressure (space) suits with with passive and/or active dust rejection surfaces.
2.         Keep suits out of habitats and design for long term with very limited requirements for maintenance or refurbishment.
3.         Bases and settlements should plan for isolated suit and equipment maintenance facilities and for a sufficient number of spare suits and critical modular replacement parts relative to length of missions and final reliability and maintainability of suits.
4.         Take advantage of magnetic properties of nano-phase iron to filter any residual dust from atmospheres.
5.         Use seals and other technology to protect moving parts, computers, switches and electrical sensors (a la the Apollo LM and LRV). 6.         Design more robust dust flaps for the wheels of open and closed cab LRVs than used for Apollo.
7.         Although long term respiratory exposure to lunar dust should be avoided, note that, after up to four inhalations by Apollo 12 astronauts, no evidence has surfaced that any physiological issues resulted.

The above approaches play forward to operations on Mars, although Mars dust will be physically and chemically different from lunar regolith dust.

 With respect to possible levitation of fine lunar dust, note the following:

1.         Both sun-lit and shadowed rock surfaces and open vesicles are clear of fine dust (although some local regolith ejecta splashes exist) even in spite of the extensive churning of the upper surface of the regolith that LROC temporally separated images indicates occurs.
2.         Although the effect of impacts was observed, to my knowledge, no indication of dust levitation was found by LADEE data.
3.         If (big IF) levitation of fine dust occurs at the terminator, it poses no significant operational problem.

Rather than wringing our hands about lunar dust, lets fund and go to work on the engineering of far more mobile, long-life, reliable, maintainable pressure suits and ancillary systems than we had for Apollo (PLSSs, camera systems, HUDs, voice activated data recall, efficient sampling tools and hand-held mineral and chemical sensors, efficient coring systems with solar wind analysis capability, cryogenic sampling systems, etc.). The A7LB Apollo suit and PLSS were great for their time but surely, after 50 years we can do much better.

If we are in error on these conclusions, please comment.


From: Brian J. O’Brien
To: Harrison Schmitt; Clive R. Neal
Wednesday, 22 May 2019
Subject:            RE: Moon Dust


This note responds to your invitation to comment if any of your conclusions on 22 May were in  error. In my opinion there is a pervasive flaw rather than error, by focus on Quote protecting humans and equipment from any adverse characteristics of lunar dust End quote. Combining humans and equipment together unnecessarily distorts and delays addressable engineering and operational approaches (AEOA) to problems with dust. It also detracts from celebrations and marketing in 2019 of research opportunities in both nano-particles and chemistry where the outermost 2cm surface of the Moon offers a nearby laboratory opening windows into Extraterrestrial phenomena of vast potential value to Earth-bound technologies and In-situ Resource Utilization( ISRU) on the Moon. It appears also outdated in this era when commerce has joined Governments in competitive and individual partnerships of lunar expeditions, particularly robotic for some years.

The flaw is clear because all 7 numbered AEOAs address issues of spacesuits or habitats. Most are therefore not relevant to most equipment or to robotic spacecraft, yet many more robotic spacecraft will be launched for lunar landings for six or more years before and after the next human spacecraft has landed. Competitive dust experiments and operations of such expeditions must focus for a time primarily on their own cost effective and successful operations.

Nor do they need operationally to be disadvantaged by putting human needs to one side. Only two of Jim's Gaier's nine categories of dust problems derived from Debriefings on EVAs of all 12 astronauts were related to human frailties, vision and inhalation and irritation ("The Effects of Dust on EVA Systems During the Apollo Missions", James R. Gaier, NASA/TM-2005-213610-REV1). Even so, robotic spacecraft have cameras and optical devices instead of human sight, and visibility problems can still occur.

The other 7 other categories of problems relayed from Apollo debriefings related to equipment, large and small:
(a) false instrument readings;
(b) dust coating and contamination;
(c)  loss of traction;
(d) clogging of mechanisms;
(e) seal failures;
(f) abrasion of materials;
(g) Thermal control problems.

These all apply to robotic expeditions here and now, and certainly until and after an Artemis timeline of 2024.

There is little doubt that modern technologies can develop much more effective seals against lunar dust problems than 50 years ago. However the same problem of proof-testing of seals remains as  it did before Apollo, despite proliferations of varieties of simulated dust.

How closely can dust simulants or old lunar samples, re-activated or not, simulate the physical and chemical complexities of fine dust on the sunlit surface of the Moon, with complex properties as summarised in your very important opening paragraph?

How closely can Dirty Thermal Vacuum Chambers simulate the complex environments of lunar mornings in hard vacuum, raw sunlight - including energetic x-rays - and bombardment by raw nuclei resident in the Sun only a day or so earlier, bombarding the dust particle and the lunar surface with a wide range of speeds, from near-thermal to some 300km/sec.. 

Harrison, you would know the answer to a much-discussed issue, of whether simulants are now available which smell like gunpowder and  also meet all other necessary Figures of Merit.  

We have already discussed possible reasons why Apollo astronauts were not given a small magnet in their geological tools, even on Apollo 17, to capitalise on JPL published discovery and further knowledge of the magnetic properties of dust, in late 1967 long before Apollo 11. 

Shared knowledge of every feature of fine dust that can possibly be measured in situ or deduced is essential for every future lunar expedition, both human and robotic. Agreement that lunar dust causes operational problems for both robotic and human lunar expeditions is a necessary but not sufficient development in progress towards being literate about cost-effective risk-management of hazards from fine dust in expeditions on the Moon. Microsymposium 60 under leadership of Jim Head and the Brown University team largely was successful here. Your note articulating the unique physical features of fine lunar dust particles is also critically important and deserves repetition.

In difficult times for funding, research of the chemistry of lunar dust should include marketing of its Extraterrestrial nature and origin. Combined with the nano-particle nature of fine lunar dust, opportunities for undreamed of expansions of both disciplines and allied technologies in Earthbound technology can surely be promoted and marketed for the Moon. And uniquely for the Moon at this  time.



(Prof.) Brian J. O'Brien
NASA Principal Investigator
Lunar Dust Expert