There's Something Weird About Lunar and Mars Soil

I put off making this video for years, partly because of how difficult the second half of my PhD was for me, but I wanted to commit to getting this out there. I'm glad I did. To be honest, I actually had fun thinking about this again for the first time in a while. Nature is healing.
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Why I don't recommend doing a PhD • Why I Don't Recommend ...
My PhD thesis: unsworks.unsw.edu.au/bitstrea...
ALRS-1 video • Mining on the Moon
InSight's seismic data from Mars paper: www.ncbi.nlm.nih.gov/pmc/arti...
If you want to hear more about doing a PhD or ask me any questions, I'll be streaming this weekend from 12 am to 2 pm Saturday GMT, which is:
Sydney - 10 am - 12 pm Saturday 25th May
London - 1 am to 3 am Saturday 25th May
Los Angeles - 5 - 7 pm Friday 24th May
Introduction 0:00
Seismic exploration 0:30
Seismic on other planets 1:39
Off-Earth simulants 2:42
Methodology 3:34
Lab results and interesting findings 4:23
Conclusion 7:08

[@spacescienceguy]

If you want to hear more about doing a PhD or ask me any questions, I'll be streaming this weekend from 12 am to 2 pm Saturday GMT. kzbin.infoYFVbW6lRB6E?feature=share Sydney - 10 am - 12 pm Saturday 25th May London - 1 am to 3 am Saturday 25th May Los Angeles - 5 - 7 pm Friday 24th May

[@steveb12]

oo I will have some questions, can you queue it up or something so I can set a notification for it on youtube

[@spacescienceguy]

@@steveb12 I'm not sure how to do that yet but I'll try! That sounds like a good idea.

[@steveb12]

@@spacescienceguy I think the terminology is "Scheduling a livestream"

[@spacescienceguy]

@@steveb12 kzbin.infoYFVbW6lRB6E?feature=share Here's the link. Thanks for the tip!

[@GT_Void]

It is because the moon soil is portland cement in a studio and the Mars soil is EARTH SOIL in the remote part of Greenland. Now you know.

[@adamseaton796]

Enjoyed the video, good amount of technical and general explanation. Subscribed and looking forward to the next one!

[@spacescienceguy]

Awesome, that's what I was going for! Thanks!

[@tamcon72]

This was very interesting to me as someone who can watch footage from rover modules for long periods, completely mesmerized, but who otherwise doesn't think about this stuff at all Thanks for posting!

[@spacescienceguy]

My pleasure! Glad you found it interesting.

[@saumyacow4435]

UNSW? Been there, done that :)

[@RickTheClipper]

The minimum I know, it is vegan

[@spacescienceguy]

I guess eating the soil from anywhere would be vegan 😂

[@justimagine2403]

Question: Is Mars our only option for visits? 1% seems too low to go.

[@spacescienceguy]

Besides the moon, Mars is the planetary body most people consider next in line to send humans to. 1% is too low for us to survive outside of a space suit or habitat, but there's a chance we could make an extended trip to Mars work!

[@sar2908]

I want to see the cat!

[@spacescienceguy]

I think around 1:46 to 2:31 is the best view you get of Gemma, but here is a picture! www.tiktok.com/@spacescienceguy/photo/7367367908135030034

[@tannerfromhighschool1338]

taric top GOAT

[@spacescienceguy]

We win those

[@michaelnoble2432]

The lowest your vacuum pump could get was 3% of Earth's atmospheric pressure? I think there was something wrong with it; even a relatively cheap vacuum pump used by HVAC installers should get down to 0.1% of atmospheric pressure (100 Pascals). Have sound propagation measurements with real lunar soil / regolith ever been performed? The Apollo program did seismic experiments, but the average velocity of sound waves would presumably mainly be determined by the velocity in rock.

[@spacescienceguy]

The vacuum chamber we used was the 12 x 18 inch Laco Technologies model and was advertised as rated for 0.1 Torr, which is less than 0.1% of atmospheric pressure. So, we were a little disappointed that we could only get to 3%. But it does depend on the pump as well. As soon as we stopped pumping, the atmospheric pressure (very) slowly crept up. Our chamber access was partly based on budget and also the fact that we weren't allowed to use the more precise clean vacuum chambers used by JPL for actual mission testing, since the regolith was, well, dirty. I'm not aware of any lab measurements of sound propagation of real lunar regolith, but if you mean in situ on the moon, yes! The below paper details some of the measurements where they were able to distinguish between the P-wave velocities of the surface layer and the deeper layers. link.springer.com/content/pdf/10.1007/BF00578808.pdf

[@michaelnoble2432]

@@spacescienceguy thanks for the response and the link to the paper! Maintaining a vacuum is certainly tricky. When you turned the pump off, did you isolate the pump from the chamber with a valve? If so, then it sounds like the chamber was at fault. Did you bake the soil first to drive off as much water as possible? If not, the outgassing water cold have contributed to this.

[@spacescienceguy]

@@michaelnoble2432 No problem! We did isolate the pump from the chamber via a shutoff valve as soon as we finished pumping. The soil was kept sealed until use, but we did not bake the soil before testing. In hindsight, this was probably an oversight. One additional observation is that if we pumped down as low as possible then left the chamber sealed overnight, it seemed the approach an equilibrium of something like 5-10% of Earth atmosphere. I wish I had done some more testing to see whether repeating this process multiple times eventually resulted in a lower pressure, or whether baking the sample first made a difference.

[@michaelnoble2432]

@@spacescienceguy not sure why KZbin deleted my comment (maybe because it had a link). Anyway, if you look up the Water Saturation Pressure vs. Temperature you will see that at 25C the pressure will be 3% of normal atmospheric pressure. This suggests it was the moisture in the soil that limited how good a vacuum you could achieve.

[@spacescienceguy]

@@michaelnoble2432 My goodness, so it is... Neither myself, my supervisors, nor my reviewers caught this. When I shared this video I didn't expect to learn something new about my work, but I'm so glad I did. Thank you for sharing. I just wish I knew this 7 years ago when I ran that particular experiment. Do you know whether you'd expect the amount of water in the chamber to eventually decrease if you just run the pump indefinitely, or is the amount of water vapour we're actually pulling out of the system negligible?

[@justimagine2403]

The cost?

[@macdmacd7896]

if we put a gigantic half of a sphere in earth orbit, will it behave like the moon?

[@spacescienceguy]

An interesting question. What's the half sphere made of? If it has the same mass as the moon, it might have a similar effect on the Earth in terms of tides, but I don't think it would be a stable shape, especially at the edges.

[@jasonz9902]

I clicked on this video thinking it was a lark "Vegan Space Scientist " and was either gonna leave a snide comment or hit don't recommend channel. I was so very wrong. It takes a lot of effort and years to get a PHD. I subbed even though you have an arbitrary diet reference in your channel name. What if you change your diet? Keto Space Scientist? You can change your channel name up to three times I believe. Think about it because I almost past your video up over the word Vegan not equating with Space and Science.

[@ASMRyouVEGANyet]

Or maybe you can learn something from someone who's different from you and has studied a plantbased diet. It sounds like you have your own biases against people. That's a YOU problem.

[@spacescienceguy]

Thank you for your candor and feedback. I take your point, but the channel name is not so arbitrary in my view. At the time I chose that name, I made videos about two areas important to me: space science and ethics (of which veganism/animal protection is a big part for me). I'm still vegan and animal protection is still important to me, but these days I focus more on the space science on this channel. I find it unlikely that I will ever stop being vegan, because it's more of an ethical view than a diet to me. But you're not the first one to make me wonder if I am missing potential reach because of the channel name which doesn't reflect what I focus on these days. I recently started making videos on Tiktok as well, but chose the name Space Science Guy there. Perhaps that would have broader appeal here on KZbin. I'll think about this some more.

[@P0thila]

Most interesting. Writing blogs such as for hub pages can get you 4x more money than KZbin unless you get tips. Easiest money in short term is Medical trials. Last but not least, most people aren’t vegan because it’s compromising and expensive including for the planet. Discuss, debate, disagree.