In this episode, we discuss Annie Lennox’s research on Mercury and biases in planetary feature naming conventions. Annie Lennox is a planetary science PhD student at the Open University.
Episode Transcript
[00:10] Marissa Lo: Hello and welcome to Geo Conversations, an interview by Geoscientist magazine. My name is Marissa Lo and I’m the Associate Editor of Geoscientist and today I’m joined by Annie Lennox, a planetary science PhD student at the Open University. Today we’ll be talking about Annie’s PhD research on mapping Mercury. During this research, Annie has come across biases in the conventions for naming craters on different planetary bodies, an issue that we will discuss later in the podcast. So thanks so much for joining me, Annie, can you tell us about your PhD research?
[00:45] Annie Lennox: My background is in terrestrial geology, but I now find myself doing planetary science, specifically the planet Mercury. My PhD project involves geologically mapping an area of Mercury. For geological mapping, Mercury is split into 15 areas called quadrangles. Mine specifically is located in the south polar region of Mercury. So my main project has been to map this area. Mercury is a really interesting place to be studying. It’s relatively unexplored: there’s only been two previous missions to Mercury, both of them NASA missions. The first one was called Mariner 10, that was in the 1970s, and that was followed by MESSENGER some 30 years later. And so it’s MESSENGER data that I’m using, imagery from that orbiter mission. This is all happening because the next mission to Mercury, BepiColombo, is already en route. It launched in 2017 – all going well – it should start orbiting the planet in 2026 with the planned science phase in 2027. So my map contributes to a global map that’s being compiled for that mission. And also, I’ve been keeping an eye out for areas of scientific interest that could be targets for BepiColombo.
[02:08] Marissa Lo: What are the main techniques that you use for mapping the surface of Mercury?
[02:13] Annie Lennox: Yeah, it’s been a real shift in perspective from applying what I know about geological mapping on Earth to a whole different planet and seeing the similarities and the differences that those reveal. But we use all remote sensing data. The primary product that I’ve been using is a base map that is a mosaic of different wide and narrow angle camera images. On top of this, we’ve also been using a DEM, a digital terrain elevation model, that shows topographic features. We have different images at different illumination conditions, and that’s really good for highlighting different topographic features, which can be very useful. And lastly, we’ve been looking at a lot of spectral, so colour maps that show different spectral signatures. And so we use all of those in combination to get an idea of what the surface looks like and also the morphology of the features.
[03:16] Marissa Lo: What are the main things that you’ve found on the surface of Mercury?
[03:20] Annie Lennox: For me specifically, the areas I’ve been looking into involve both craters and also effusive volcanism. So I’ll stick with the craters, first of all. The whole of Mercury’s surface is really quite heavily cratered. It’s one of the primary geological processes that shapes the topography. And so I’ve been looking at the south pole and I found a couple of craters that have really interesting ejecta deposits, now, that’s material that, when an impactor hits the surface, that’s the material that gets excavated, so thrown up into the air. It falls following ballistic trajectories and deposits, as it’s sometimes called, a blanket around the crater. Generally, the thickness of that ejecta deposit thins with distance from the crater.
Now, I found a couple really atypical craters at Mercury’s south pole. These are called lobate ejecta deposits, and they differ from normal craters in that they maintain thickness with distance from the crater. And at the end, at the margin of this deposit, it can be lobate and also quite steep. I’d found six within this specific area, the south pole, and before that there had only been around a similar number that had been reported globally. So that was quite unusual in the first instance. In the second instance, there had been a bit of ambiguity as to the timing of formation of these features, whether they formed at the same time of impact or after impact in some sort of mass wasting event. And so, one of the craters I found Nairne crater had pools of impact ejecta that sat on top of this lobate ejecta. So that gave the first evidence for timing of formation of these features. The lobate ejecta must have formed prior to the deposition of the impact melt, which happens fairly early in the crater forming process. That’s been, kind of, the first area of spin-off science, as we were calling them.
The second one is, as I was saying, effusive volcanic deposits. All of Mercury’s surface pretty much is characterised with lava plains, but they didn’t all deposit at the same time. Some of them are considerably older, some of them considerably younger. The youngest widespread ones are around 3.5 billion years old – so when we say young, we don’t really mean young on Earth timescales! And it’s generally accepted that that age of about 3.5 billion years ago is the age at which effusive volcanism stopped. Now, effusive volcanism is a style of volcanism that, instead of being explosive, is more like steady and voluminous outpourings of magma onto the surface. We know, and there’s very good evidence, that explosive volcanism continued into Mercury’s quite recent history. But there hasn’t been as good characterisation of Mercury’s small scale effusive deposits. So I’ve done a global survey looking for these patches. Now, they’re very smooth, they’re usually quite small, they’re always, kind of, hundreds of kilometres along their longest axis, and I have found them globally. Now, these potentially represent a protracted waning phase of effusive volcanism on Mercury.
[06:47] Marissa Lo: For the lobate ejecta, why does that only happen sometimes and not for every crater?
[06:55] Annie Lennox: There are a couple different potential controlling factors there. One thing is there’s almost certainly a topographic control. What I mean by that is the craters that are host to these lobate ejecta deposits are very rarely impacting onto smooth topography. Instead, what is much more common is that they are impacting on the edge of an older pre-existing crater. And so that has a control on the formation of these features, in that the ejecta that’s been deposited preferentially is deposited into this older underlying crater.
[07:35] Marissa Lo: Yeah. Then thinking about the effusive volcanism, you mentioned that Mercury had a period of effusive volcanism earlier in its geological history compared to explosive volcanism. Do we know why that happened? Can that tell us something about like the thermal history of Mercury?
[07:52] Annie Lennox: Absolutely, yes. There are certainly theories that relate to its thermal history. Mercury as a planet is shrinking. That’s because it’s cooling and that cooling induces contraction. And that contraction has the effect of reducing its radius. That is what’s formed all of Mercury’s tectonic features. So that’s the reason that, on its surface, you see these big networks of lobate scarps, so they’re called – but these are all thrust faults, the surface expression of thrust faults from depth. But not only that, it doesn’t just link to tectonism, it’s also linked to volcanism because, in this contraction, the pathways that allow for magmatic ascent are being cut off. And so, magma cannot reach the surface in the ways it used to do. And that’s why I’ve been finding with these small patches, there’s a really strong association between them and tectonic features. Potentially the reason here is that the tectonic features, the fault itself is a structural weakness and maybe this magma can exploit those structural weaknesses to get to the surface despite the global contractions.
[09:03] Marissa Lo: So you already mentioned that you started looking at crater names, when I believe you got to name a crater yourself. Can you tell us a bit more about that?
[09:12] Annie Lennox: Of course, that has probably been one of the most exciting and unexpected parts of my PhD! Yeah, the Nairne crater I was talking about earlier that had these lobate ejecta deposits, that was actually the first crater I got to name. I knew I wanted to name my first crater after a woman because I could see within the area that I was mapping that there was a seemingly poor gender representation within the area. And to give a little perspective, when I started mapping that area, there were 37 named craters. And I counted that just 8% of these were named after women, which is not unexpected, but was pretty disappointing. And so Nairne. The name comes from Lady Carolina Nairne, who was a poet in Scotland whose songs I grew up singing as a wee bairn. She’s a bit of a fascinating case. She didn’t generally publish her poems or songs under her own name in her lifetime. And that’s because she was of quite a well-to-do family and it wasn’t really considered proper at that time for her to be a poet. And so, it wasn’t until she died that the songs were correctly attributed to her. In many instances they were attributed to Robert Burns, who also has a crater on Mercury. So it was a really, I think, a nice circular moment that she didn’t really get the recognition she deserved in her own lifetime and now she’s kind of represented on a whole other planet! I do love that. But the whole process there really brought to my attention the underrepresentation of women in space science nomenclature. But it’s very much not limited to an issue of gender and there is a wider, broader sense of diversity that is lacking in our space science nomenclature.
[11:02] Marissa Lo: What do you think the effect of that is? You know, what are the issues with having that bias in the names of craters on other planetary bodies?
[11:10] Annie Lennox: The whole sector of space science, and science in general is seeing this shift towards being far more inclusive and encouraging all forms of diversity. But we can’t do that just trying to convince people that they should be involved in science. We need to make sure that our scientific systems already in operation are fair and are promoting diversity. And, at the moment, that’s not happening. We have this incredible database, in terms of nomenclature, we have this database of named features on every planetary body that we’ve seen – and there’s not disaggregation of that data. We don’t know the type of diversity that is perhaps overrepresented, perhaps underrepresented, or even missing entirely. And so, without realising that, we are continuing to expand the nomenclature without proper awareness of the social implications or the degree of diversity that’s being achieved.
So when it comes to naming conventions, you can’t just name any feature after anything. But conventions are set and maintained by the International Astronomical Union (IAU). And a common convention, although not exclusive to all features, is that features get named after real people. There are slight issues within those conventions that might actually have a negative effect in terms of diversity. First amongst them, if you’re wanting to represent a real person, that person has to be deceased for a minimum of, I think, three years. They also have to be demonstrably famous for a minimum of 50 years. Now, there are a couple, I think, potential issues with those requirements. Firstly, if we are looking at exclusively a pool of 50 to 60 years ago, you know, when we think of people who are able to achieve fame from that point going back in time, that’s not necessarily a very diverse pool. Additionally, if we’re going to judge them in terms of fame and recognition, well, those are metrics that were very much designed by and designed to benefit the patriarchy. And so people’s stories from marginalised groups are not so well known, they’re not so well preserved. And so if that’s going to be a metric by which you have to demonstrate in order to have representation now, that’s always going to look like we have really poor diversity, which I think is a bit of a problem. So when you submit the request, you present the feature, you explain why it’s scientifically interesting, and why it’s deserving of a name and you get the opportunity to suggest a name. Now, it’s not guaranteed that that name will be selected. That ultimately is down to the International Astronomical Union, the IAU. But provided that your name fits with the convention and the rules and regulations that are in operation, then there’s no reason as to why that shouldn’t be accepted.
The IAU are very vocal about trying to go for, they call it internationality in their choice of names. So they do really consider geographical distribution when it comes to naming features, which I think is great and absolutely should be the case. I do question why it’s kind of only internationality that’s being protected or preserved. You know, there are so many more forms of diversity than just geographical distribution and they don’t have the same support in the legislation, which I think is a little unfair.
[14:50] Marissa Lo: What can planetary scientists do to change these biases? And how have you been trying to tackle these biases yourself?
[14:57] Annie Lennox: I think a really major thing is awareness, because you can’t expect people to assume that the scientific systems that we have are unfair. You know, the more we talk about it and the more we make people aware that we have gender diversity, and yes, we have diversity towards European names – but that’s not the only form of diversity. We need people to know this so that going forward they might consider this when they’re suggesting names themselves. But I’ve obviously looked quite in depth into the gender diversity. Like I said, this is not the only type of diversity that’s lacking. But I have found that considering all of Mercury and looking specifically at craters, because these tend to be named after people, I found that only 12% are named after women. When we look to Mars and the Moon, that shrinks to 1.8 and 2%, respectively, which I think is really pretty poor. Now, part of this is to do with the convention on Mercury: craters are named after artists, so they can be painters, your authors, you know, almost all forms of art are represented here. On Mars and the Moon, it’s scientists and astronauts and careers and areas of work that are historically more exclusionary towards women in marginalised groups. But even with Mercury, with a representation rate of 12% for women, I think that’s pretty poor. I mean, women have always been scientists and artists. It’s just that their stories aren’t so well known or aren’t so recognised and their contributions not celebrated in the same way. So I had identified this gender imbalance and looked into that quite a lot myself. But as I’ve been saying, this is absolutely not limited to an issue of gender.
So I’ve been planning these data entry hackathons. These are open to all people, so we’ve had people join from across the world. They have been both in-person and hybrid online, so you can join from anywhere at any stage. You don’t have to be a scientist, you just have to care about representation! That’s really the only criteria. And with these hackathons, we have been going through every named feature in the entire Solar System and working out the protected characteristics of the eponym. Now, that’s quite hard to do. To break it down, it’s looking into the gender, the sexuality, the ethnicity, and the nationality. It covers a lot of different types of diversity. Of course, there are massive challenges with this, you cannot physically go back in time and ask that person how they identified. And so, a lot of what you’re doing ends up being interpretations from what is preserved about that person’s life. So it’s not going to be 100% accurate. In having this, it’s going to provide the groundwork that we know the kind of levels of diversity as they currently stand. And I think it’s vitally important that we do know that so that we realise going forward who is missing and who we ought to represent better. And hopefully that will have a profound effect on diversity in the nomenclature going forward – that’s the goal!
[18:17] Marissa Lo: So we’ve talked about these conventions that the IAU have. Is it possible for those to change?
[18:22] Annie Lennox: The IAU are very explicit in that naming features after a real person is not done to commemorate that individual, but rather it’s done for scientific needs, which is absolutely true. However, in a way, that person is being represented and it does matter who we name features after. I’ve got two nice little case studies of changes that have been made, which shows that changes can happen and should happen going forwards.
The first revolves around the name Neruda. There was a Neruda crater on Mercury that was named after the Chilean poet, Pablo Neruda, who by his own admission, was a misogynistic sexual abuser. Myself and my colleague, Ben Mann, and our supervisor, David Rothery, brought this to the attention of the IAU: perhaps this isn’t the kind of person that we should be representing. I don’t really advocate for the wide scale renaming of objects. I know that they’ll just confuse the literature and what have you. But we got a nice little solution with this one where they decided to keep the name Neruda but change the origin. So we found two other alternative people who also had the last name Neruda. Both of them, I think, were Austrian, one of them was a composer. And so now that Neruda crater reflects their origins, rather than Pablo Neruda, which I think is a really nice way of getting around that. Also, if we do a bit more of this multiple origins for one name, we might get over an issue of, kind of, de facto male occupation of space. What I mean by that is these names, kind of, come as a first comes, first serve basis. You can’t have name duplication between planetary bodies, so I couldn’t have Mrs. Smith’s crater on Mercury because there was already a Mr. Smith on the Moon. And so we have this male occupation of space in that, because historically space science was dominated by cis white men, these tended to name features after cis white males. So if we could allow for dual origins, perhaps you could get more women represented!
Another bit of change that I’ve experienced recently is, I suggested the name Kngwarreye. Kngwarreye was an aboriginal, Australian painter, really well celebrated, incredible works, who I tried to get a crater named after. And at the, kind of, pre-screening stage, I was suggested by the relevant working group to change that name request to a name that wouldn’t be considered so difficult to pronounce. I think that’s a piece of implicit, perhaps explicit bias in space science. You know, to whom is this hard to pronounce? You know, if you took the time to learn the name, all of those sounds are widely heard in the English language. We kind of went back to the USGS and IAU about this and said that rejection on the basis of pronunciation is discriminatory. And so, I was allowed to resubmit that name. Unfortunately, it got rejected anyway because we didn’t have demonstrable fame that she’d been famous for 50 years. But it did bring about a nice bit of change. And after a wee while I heard from the President-elect of the International Astronomical Union that they were going to change the rules such that rejection on basis of pronunciation should not happen and will not happen going forwards. So I think this really nicely proves that conventions and these rules can be changed. And so long as we build a case as to why they should be changed, that being that there’s a current lack of diversity, I hope that going forward that change will be enacted on.
[22:13] Marissa Lo: Thank you so much, Annie. It’s been such an interesting discussion and all the best with your future research and all the work you’re doing with crater names.
[22:22] Annie Lennox: Thank you so much, Marissa.
