Scientists, including one from Indiana, are asking NASA for a chance to examine soil samples taken from the moon more than 45 years ago. Some say it could provide information we need to develop a permanent human presence there.
Astronauts brought sealed samples from the lunar surface back to Earth after the Apollo missions. Many of those samples were opened and examined, but a few were placed in another container and sealed again.
A recent paper proposes that it's time to open those samples up.
We spoke with Clive Neal, a University of Notre Dame Professor and the paper's co-author, about what could come from opening the samples.
This conversation has been edited for clarity and conciseness.
Q: What can you tell me about the samples collected during the Apollo missions?
A: There are certain samples that were collected during Apollos 16 and 17 that were put in special containers. They were sealed on the surface of the moon, and they were brought back for more detailed analysis of the volatile content. These two particular samples – there are two particular sample containers, one from 16 and one from 17, that were never actually analyzed. Shortly after they were brought back, those containers were put in another sealed container.
So they were double-contained, so to speak. And then they've been waiting for analysis, basically for 45 years. We are now at the point where we have the technology and the analytical capability to actually start to pull apart these samples and understand, not only their volatile content. But they're now being treated as new samples from the moon because, well, we've never seen them before. So it is an exciting time. NASA now thinks that this is an important point to make in terms of our nation's return back to the moon, and we'll hopefully have a chance to start opening these samples.
Q: Why has it taken so long to look at them? Why were they left sealed?
A: Why were they left sealed, is a very good question. There's a number of reasons. In the early days, there were a lot of samples that were available. As the interest in the moon has waned a little bit, there weren't so many people requesting samples. Then the corporate knowledge of what was actually there also dwindled as people retired and were no longer active in the field. So it's taken a few of us to dig a bit deeper and find out more about these samples.
We actually knew about them, I'd say, about eight years ago. And we've been trying to get a consortium approach together, so that many people can look at these in order to actually open these samples in a way that we'll be able to understand the volatile content. The volatiles are quite important these days, in terms of understanding how they are bound to the lunar soil, and we're hoping that they may preserve that signature. We're not counting on it, but we're hoping they may preserve that signature. Because as those samples came back, they get shaken in the return capsule, and it may have liberated those volatiles. But in these samples, they may have been contained.
Q: You've mentioned "volatile content" a few times. What does that mean?
A: Well, the surface of the moon is continually bombarded by the sun. And the sun implants different species – hydrogen, nitrogen, carbon and oxygen – to [the soil]. These, we think, are loosely bound to the regolith. We've actually now got instrumentation that was orbiting the moon that could show that hydrogen signature during the changeover between lunar night and lunar day. It seemed to condense there during the lunar night, and some of it got driven off during the lunar day. So we now have a much better understanding, thanks not only to the samples that have been looked at, but also the missions to the moon since Apollo, of how the lunar soil interacts with the sun.
This becomes very important in terms of hydrogen. We actually showed with the Apollo samples, that if you heat up a piece of regolith that's had hydrogen implanted in it by the sun, if you heat it up in a vacuum, you can actually get water to form due to the reduction of some of the minerals. They take the oxygen from those, and it can actually combine with the hydrogen and form water. And as we look forward to actually getting a human presence on the lunar surface, you need oxygen and you need water. This is one way to get it.
Q: What are you hoping to learn from these samples?
A: That's a good question; it depends what is in there. We do know that one of the Apollo 17 samples was taken from basically an avalanche or a debris flow. We have some samples from that. But with the orbital data that we've now gotten, we can now make predictions of what should be in that particular debris flow. We would then be able to test those predictions on the basis of the orbital data with these new samples, or these unopened samples. That is one thing that could be done. That's why we're treating these as new samples that we can actually use to ground truth the orbital data.
Q: How good are the seals on the samples? What are the chances they've been contaminated since they were brought back?
A: They've never been opened. The only contamination would come through leakage. So that's the other point of opening these samples, is we need to prevent contamination. We know that lunar samples are very quick to absorb humidity; that has been shown in some of the early studies. They would have to be opened in a very dry environment in order to test these and look at the uncontaminated volatile content. So actually preparing to open these samples is going to be quite intricate and detailed.
Q: What will that process look like?
A: We have a couple of strawman ideas in terms of the sequence of events that would have to occur. We have to be able to drill into the containers and extract any gas that has been liberated and contained therein. We call it the "headspace gas," and we want to analyze that to get an idea of the bulk composition, if you'd like, of any volatiles that will be liberated.
Once we open up the containers, we would like to preserve them in as pristine a state as possible. Obviously, we can't have a very high vacuum, but we can try and make the atmosphere as benign as possible, or as unreactive as possible. So for example, the other lunar samples are kept in a very dry, nitrogen atmosphere. That's one thing to look at, but we're still working out what would be the most optimal and cost-effective way to do this.
Q: Is there any reason not to open the samples?
A: I would say no, but I could be biased. I'd say now is the time to open it up, with our nation's refocus back on the moon. We also had a lunar science for landed missions workshop at NASA in California in January, that is looking at potential landing sites for commercial-provided landers and potential sample returns using that, as well. There is a very good likelihood that we will be getting fresh samples from the lunar surface very soon. So we need to better understand from these samples that we have that have been contained, the ways to actually preserve that pristine signature. It takes on a whole new emphasis in terms of, are we processing them the right way at the present time? What changes need to be made so that we can better preserve these types of samples in the future? So now is the time to actually look at them. And it may even give us an indication of potential resources that can be used to not only promote human presence on the moon, but also develop a business case for commercial vendors and create jobs for, certainly, the students at Notre Dame.
Q: Is there a timeline for this? What's the next step?
A: So the next step here is that we have to write a proposal to NASA. And NASA is going to supply us with an announcement of opportunity to propose later this year. I am hoping that within two years from now we would have begun the process to actually start to open these samples. We'd have the procedures worked out and would actually be able to understand what these new samples are going to tell us.
Q: Is there anything else you'd like to add?
A: I'd just like to say this is an opportunity. People like to think of space exploration as a massive drain on the nation's resources, but this is the first step in showing how you get a return on investment. I think we have to think of the moon as a job creation place these days, given private sector interest in space travel. SpaceX, Blue Origin, Moon Express, Astrobotic. It's not just within the U.S. There are international companies, such as TeamIndus from India and iSpace from Japan. They are very interested in accessing the moon, they're very interested in seeing what resources are there that they can potentially use as a product, and I think this is a very exciting time not only for the moon but also the future of human space travel. And also for the job prospects for future graduates of our universities.
