InSight, Mars, NASA, Observation ESFELS2021: Mark Panning
This is the the full list of authors, which is really just the the proposal team right here, this so uh. You can see on the list to hear it theres a lot of uh a lot of seismologists on this list, um and uh um, and also some some some great technical people that are are are going to be delivering this instrument suite to to shredding our crater On the far side of the moon in the prism 1b mission, um lets see here: okay um, so this is kind of the the whole talk in one slide. Um. So, im not going to talk about everything on here, but you know when you go back to the recording and look and see whats whats there, you can see uh the whole story in one slide, uh if youre interested in and so what were doing with our Side, seismic suite is were delivering uh a couple seismometers a vertical component, very broadband seismometer um, which is the most sensitive seismometer to fly on a planetary mission, um and also a capable compact, three component short period seismometer, and these are both based on instrumentation of the Insight mission, which is operating on mars right now, in fact, the very the vbb is actually using a flight spare from from the uh from the insight mission and um and were putting all of these inside a thermal enclosure that has its own independent command, power and Communication system so effectively or a cubesat without propulsion and uh.
The idea is that we outlive the commercial lander, continue operating through the night and recording data communicate during the day and last for a nominal mission of four months. In order to record the moonquakes. We want to see and uh were aiming at three primary science goals in this process were trying to look at um the far side seismicity, which has never been analyzed, because all the apollo data comes from the near side, um and and look at implications thereof. Um were also looking at the local crustal structure, underneath uh schrodinger, crater um, and linking that into global crystal models and finally um. By putting such a sensitive instrument out there, we can record the background. Seismic noise, better than uh, was, has been possible in the past, which can be linked to micrometeorite impact rates. So those those are the three main science goals. So you know now that you know the whole story in advances, lets step back and think about how we do seismology on the moon um its its uh uh, very different than than earth seismology in a lot of ways so on over here on the left. Ive got two seismograms that are both one hour long um one is from earth, one is from the moon, um same time, scale um, similar sized uh events um, and you could see that the moon is very, very different than the earth. So on the earth we get nice clean, arrivals um.
They give us this this nice spike here showing up on the moon, the the scattering the seismic scattering is intense and everything oscillates for long periods of time hour, an hour or hours and uh. This adds a lot of complication to how you do seismology on the moon, um and uh, and this the apollo measurement, of course, were only made at near side landing locations so by uh. Taking these modern sensitive instruments on the far side of the moon and adding in modern digitization, i mentioned digitization here, because i show a recording of a small moonquake here at the bottom, which shows the limits of the the i believe, 7 bit digitization used by the Apollo instruments, where a lot of uh a lot of small moonquakes, look more like barcodes than seismograms and uh. This is this was a fundamental limitation of what could be done for the small events and the background noise for uh, apollo instrumentation so were really uh. Getting a chance to explore a lot of new ground here in this in this far side mission, um, just in a little more detail here, uh, this is plotting um, the major uh seismicity locations uh, as recorded by the apollo stations um during the 70s and uh. Most of these, although these circles here are locations of deep moonquakes, these happen, hundreds of kilometers, deep and hap, and they tend to be happen in repeating clusters. So they happen over and over again at uh repeatable times in the title cycle: um and then the blue stars are shallow moonquakes, which are the larger quakes that happen once every several months or so um and uh, and you can see the the orange box is Highlighting the near side of the moon, basically all of the seismicity observed, is on the near side, with the exception of a couple deep moonquake clusters that that uh move over to the far side, and so the question we yeah we have to ask is: is there A fundamental difference between near and far side, or is this simply a a a an artifact of of the detection capability of the apollo instruments.
Um due to deep mental attenuation, not letting us see uh, far side paths as well um, and so by going to the far side, we can directly record far side seismicity as well as uh recording or not the the known repeating deep moonquake locations on the near Side which lets us constrain that deep mantle structure and understand what were looking at in a a much more uh clear way. Um sharing your crater is a fascinating sight. I mean you can i over here you can see its just a its just. A beautiful crater, with a with a nice peak, ring its very clear its sitting right on the edge of the south pole. It can basin so its a beautiful crater within a larger crater. Its got uh smooth floors that are likely impact, melts uh its a really interesting location, um in and of itself and uh. We uh with our recordings. We should be able to look at techniques like receiver functions which look at conversions of stuff coming through the crest underneath the site. This is some example of some work. Weve done on mars, like this and similar work has been done, uh with the apollo records, but uh. We we are looking forward to getting this with with modern, clear, instrumentation, um and theres lots of different ways. We can try to look at the local crusters local, crystal structure, which then lets us look think about trigger crater itself, but also link into the larger gravity derived models for the whole lunar surface.
The background noise is also a really important thing to say. As i said, the apollo instruments were actually limited by that coarse digitization, so we didnt record the background noise. In most places we just got the instrument noise um so but uh. The the vertical vbb um is. Is these two blue lines? These are estimated uh sensitivity and displacement compared to apollo, so were pushing down the noise floor of the instrument itself, which lets us hopefully measure the the lunar noise floor or at least put a new lower upper bound for what that lunar. Noise level is, and the prediction is that that that noise level is actually driven by the more or less continuous impacts of micrometeorites. So this lets us directly link to the micrometeorite impact rate, which is actually not all that well constrained and, of course, thats. A pretty important goal for understanding when, if were looking at long term, human safety uh for human occupation of the moons, because those little micro meteorites are going to be impacting everything on the surface um. One of the first questions that always comes up is, is you? May have noticed in the pictures that the uh the package is sitting on the lander deck and uh well be recording through the lander um and uh. If for those who have paid attention to planetary seismology, um uh, both the viking mission and and the insight mission before deployment taught us a deck mounted, seismometer is a problem um and uh, and and that that is true, so heres heres, the seismometer on on viking, Which uh never actually recorded a mars quake, or possibly only recorded um one and uh uh, but we did some analog experiments, sticking seismometers on the deck of the the curiosity rover engineering model, uh in the mars yard, uh at jpl and uh another one immediately below And uh across the frequency band that starts below the lowest, resonant frequency of the lander and down to uh 30 second period or so um you that we actually got very clear coherence between the two records.
The the recording on the deck was effectively identical to the recording on the ground could record seismicity on earth quite clearly, but one thing we noticed interesting is during the day we had some decoration because of the activity of the air conditioning in the hangar, where the The engineering model was stored, and this is totally analogous to the problems faced by viking and insight, which were related to wind, of course, thats, not a problem on on the moon. There is no wind um, however, we will be uh having having to deal with thermal noise uh at dusk, at dawn, um and uh. This is analogous to the thermal moonquakes that are actually measured by apollo instruments that were put well away. Um so, but well see. Well well, see well lose some data around that time and well lose some data at high frequency above the resonant frequency of the lander. But we should be able to record good data across the broad frequency band and during the times away from large temperature changes. Um. The a little bit more about the seismometer. This is a flight spare very broadband seismometer from the insight mission rotated to measure vertical instead of at a tilted axis, with a with a spring change required to account for the different gravity on the moon compared to mars. This is contributed by canes in partnership with uh, ipg, paris, um and uh um, and so this will be delivered and give us very high sensitivity, um the three component short period seismometer.
That looks like this: its set up in a galperin configuration which three tilted seismometers that all all measure a tilted axis, so theyre all identical, but you can combine them to get the full three component system, its a new build, but its based on the insight heritage. Um and this one will be directly delivered by kinemetrics incorporated, which is a a leading manufacturer of seismometers and uh seismic data equipment um and is in collaboration with oxford and imperial college. London um – and this is uh – a micro machine silicon system um just a little bit more about the sensitivity here. These are uh um. Some plots of this uh uh compared to what we believe our requirements are to get. The number of mood quake recordings were expecting um and uh compared to some of the apollo data here, um and so and were were really looking forward to getting this high quality data on the moon, um um. The package design, as i said, is, is a is a pretty innovative system. Uh and its you know its its um, its basically a box within a box with with spacerless uh multi layer insulation put in between the two boxes, which gives us excellent thermal control, um, and that lets us stay warm through the night, thats, the and so the Batteries function well, uh at the warm temperatures and we can maintain operation through the night um running at about five watts, which uh to keep the instruments running and all theyre doing is uh passively running and recording the data and then, during the day, um the commands.
The command and data handling system kicks in um and does com activities etc. Communicating with the uh planned relay satellite and that all of the command and communications and power systems are based on marco flight. Spares and theyll be delivered by the group led by jamie cutler. At the university of michigan, um um im flying through this, but uh lets see here so uh um. The one question you might ask uh, given what im talking about here and what bob gribbs going to talk about next um. An interesting thing here is that this. This prism, one b mission destroying your crater, includes far side seismic suite, which has uh the the the two different seismometers theres, also litmus, which will include a magneto, tolerant measuring system and a heat flow measurement system and lucy, which uh is led by uh, stuart bale. Uh out of berkeley uh, which will have a lot of uh uh magnetic measuring equipment, electro electromagnetic measuring equipment and um by combining all of these weve actually got most of the primary instrumentation or something analogous to the primary instrumentation proposed for the lunar geophysical network, which Was uh you know recently, uh re explored in a planetary mission concept, study led by clive, neal uh last year and um, and i i think its worth mentioning that this is this is exciting, because this means is effectively um somewhat of a test node. For for a potential future lunar geophysical network um, it has – and you know, weve weve – carefully defined some great science goals that we can reach with a single, relatively short lived um station.
But a long lived network still, i think, is an important goal for the future of of uh exploration science on the moon, um uh. You know we we with a network. We can locate uh events much much more reliably and uh have many more events to look at um and uh, and this this long, the the long lived network data samples, the whole moon, whereas were only focusing on the one area we can. We can really access with the schrodinger crater site, but this you know this. This idea is that this can be a key pathfinder for lg, so we can look at some of the trade offs of an undeployed package. Obviously, uh inside has taught us that deploying to the surface is helpful, um and, and but you know this lets us quantify the trade offs of that uh, because there are big cost differences between having a whole robotic system for deployment or remaining uh uh mounted on The lander and this lets us demonstrate the instrumentation and uh this this. The system weve got for night survival, um and long term operation is a system that could be used um, either within the context of lgn or or in future prism missions with other instrument suites. So this is uh, exciting and a lot of those ways. So, just to summarize it all up here, um far side, seismic suite were designed to go to the moon, outlive the commercial lander delivery system and were looking at some key lunar science from the far side of the moon, um and so were looking at far side.
Seismicity rate is there a difference between the near side and the far side, or is this due to deep mantle attenuation um, looking at the crustal structure, at both local and global scales and looking at this micro meteorite impact rate? Through the background, seismic noise, um and um i this is the the the combination of instruments are very uh, complementary on prism, 1b and so im really looking forward to to have this um geophysical package uh delivered to the far side.