Author
|
Topic: Artifact retention: risks, hazards, mitigation
|
SpaceAholic Member Posts: 4437 From: Sierra Vista, Arizona Registered: Nov 1999
|
posted 12-14-2016 08:04 PM
For those of us who collect aerospace technology, a note reminding folks that NASA contractors responsible for design and fabrication of components as well as selection of materials, had as their primary focus ensuring optimal form, fit, function, weight, operational suitability/effectiveness and a short term safety/acceptable risk profile compliant with specific criteria to an associated application. Collector ownership was not a design consideration and those same engineers probably never envisioned post mission enduring relationships between the (now) artifacts and cS members. Many biologically incompatible materials are incorporated into space systems. These include substances that are recognized carcinogens or otherwise toxic to the body either immediately or via extended exposure if ingested, through skin contact, proximity. Some examples include heavy metals such as beryllium; perchlorates, hydrazine, fibrous materials (Asbestos and other Silica-based), radio-luminous sources and radioactive components incorporating radium, thorium, promethium — others to numerous to list here. However for anyone who currently owns or is thinking about adding spacecraft or propulsion artifacts to ones collection, it's important to get educated on the types of materials utilized in its fabrication and then to determine if it's a risk that can be mitigated via adoption of specific handling and storage practices. In some instances given the condition of a piece or the nature of the risk a collector may just have to pass on assuming custody. When considering mitigation too, it is always advisable to understand inherent risks of ownership in the context of family members or other cohabitants who may have the possibility of interaction with the piece. As an example, this Gemini/Skylab T002 navigation sextant looks innocuous but merits some attention having been assessed via initial Geiger Mueller survey to be an elevated emitter of ionizing radiation. Note that the sextant is kitted with two lens to support IVA (short relief eyepiece) and suited/EVA (long relief eyepiece). Photos show subsequent measurements taken with Gamma scintillation detector. Image 2 and 3 show isolation of offending component to the installed long relief eyepiece with elevated gamma emissions of approximately five times normal background. Image 4 captures measurement of sextant with installed short relief eyepiece/normal radiation levels (essentially background).The energetic eyepiece lens element (closest to eye when using the assembly) is fabricated in part from thorium oxide (doping with thorium was used to reduce dispersion – its use as an additive was not unique to high end lenses throughout the camera industry, however it's a bit unusual to have it in an eyepiece). As a gamma emitter, even at this relatively low dosage rate, consideration on where/how the eyepiece should be stored to preclude long term exposure risk (i.e. I would not want this lens retained in a location where I spend a lot of time). Radon gas emission from the lens is also a possibility. And if the lens is scratched or chipped, though unlikely, thorium could be ingested increasing the possibility of internal radiation related illness. The yellow canister near the top of the second image is a lead "pig" that will be used to temporarily store the thorium eyepiece until it returns close to background. Given that thorium has a 14 billion year half life, it will be a while but I am a patient guy.
|
David Carey Member Posts: 782 From: Registered: Mar 2009
|
posted 12-14-2016 11:25 PM
Nice piece and interesting write-up, Scott.If you need "off-site storage" for the sextant while the Thorium decays, I'd be happy to help! |
rgarner Member Posts: 1193 From: Shepperton, United Kingdom Registered: Mar 2012
|
posted 12-15-2016 04:24 AM
This is a brilliant post. I have wondered for quite some time about space shuttle tiles and other heat-resistant materials. Some shuttle fabric has what would appear to be, at first glance, cotton inside. This is of course not cotton, but when I first saw it the first thing that came to mind was asbestos. |
GACspaceguy Member Posts: 2474 From: Guyton, GA Registered: Jan 2006
|
posted 12-15-2016 05:07 AM
Very good info here. I keep most artifact type materials behind glass and away from any touching hands. Never thought about coatings though.I am not exactly sure what I am more impressed by, the fact you know all this or that you have the test equipment to verify it. Thanks!! |
SpaceAholic Member Posts: 4437 From: Sierra Vista, Arizona Registered: Nov 1999
|
posted 12-15-2016 05:32 AM
quote: Originally posted by rgarner: I have wondered for quite some time about space shuttle tiles and other heat-resistant materials.
Certainly would not want those fine glass like particles easily generated as a byproduct of possible shuttle silca ceramic tile fragmentation floating around home and entering a young one's lungs. Regarding Thorium... it was also heavily leveraged within alloys to fabricate light weight electronics and structural components. Thoriated Magnesium for example comprised casings for some Gemini and Apollo electronics. These should be recognized and handled accordingly as they are primarily alpha decay emitters and even small abrasion or scratching of the surface can liberate particulates that you would not want entering your body. |
Charlie16 Member Posts: 494 From: Italy Registered: Dec 2010
|
posted 12-15-2016 06:38 AM
Great Job Scott, thanks for sharing. |
rgarner Member Posts: 1193 From: Shepperton, United Kingdom Registered: Mar 2012
|
posted 12-15-2016 06:52 AM
quote: Originally posted by SpaceAholic: Certainly would not want those fine glass like particles...
Of course, one should always be careful with anything "dusty." I frequently work with moon and mars meteorite dust, and you don't want that getting on your chest either!But I do still wonder if there is anything toxic or even carcinogenic in shuttle tiles and foam. |
SpaceAholic Member Posts: 4437 From: Sierra Vista, Arizona Registered: Nov 1999
|
posted 12-15-2016 09:09 AM
Silicosis is the principle risk from exposure to HSRI generated silica particles. U.S. government offers guidelines when handling this material to reduce impact to health. |
rgarner Member Posts: 1193 From: Shepperton, United Kingdom Registered: Mar 2012
|
posted 12-15-2016 09:36 AM
As usual, your help is second to none. |
YankeeClipper Member Posts: 617 From: Dublin, Ireland Registered: Mar 2011
|
posted 12-17-2016 04:25 PM
Great post Scott — very thought-provoking.As regards Foreign Particulate Matter (FPM) in an environment, factors such as particulate composition, mass, shape, electrostatic properties, aerodynamic size distribution and airflow will be key determinants of what is in the air at any given time. Different size particles have different settling rates — larger particles generally settle faster, smaller particles stay suspended in the air for longer. Reintroduce airflow and human or artifact motion and settled particles get re-suspended. If particulate matter deposits on clothing and/or body surfaces it can be carried and redistributed through a home or office as part of every individual's "personal cloud" of particulates. Cross-contamination of other surfaces and people is all too easy. As regards inhalation, particles greater than 5 micron generally impact in the oropharynx and get swallowed. Particles 1-5 micron in size are inhaled, deposit and remain in the lungs, whereas particles less than 1 micron may stay entrained in the air stream and be exhaled. |
hidaleeho Member Posts: 57 From: Denver, Colorado, USA Registered: Dec 2011
|
posted 12-17-2016 09:31 PM
A great post! Assuming "things" are benign is ignorant. I would imagine most of us have been unaware of the hazards of items that have passed through our hands. Probably impossible to know everything, but it sure pays to be aware of possible hazards. Safe collecting everyone. |