Planetary Radio • Sep 04, 2019

A Comet’s Legacy, and a Helicopter is Ready for Mars

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On This Episode

20190904 j bob balaram

J (Bob) Balaram

Chief Engineer for Mars Helicopter Scout Project for JPL

20190604 martin rubin

Martin Rubin

Researcher for University of Bern, Rosetta’s mass spectrometer team

20190604 cecilia tubiana

Cecilia Tubiana

Research scientist for Max Planck Institute for Solar System Research

Bruce betts portrait hq library

Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

Kaplan mat headshot 0114a print

Mat Kaplan

Senior Communications Adviser and former Host of Planetary Radio for The Planetary Society

First we return to JPL for an update on the Mars Helicopter that has just been attached to the belly of the 2020 Mars Rover. Then it’s across the pond for a review of the amazing science coming from the Rosetta mission that spent years exploring comet 67P/Churyumov-Gerasimenko.  We wrap things up with another What’s Up view across the solar system and beyond.

Attaching thermal film to Mars Helicopter
Attaching thermal film to Mars Helicopter Members of the NASA Mars Helicopter team attach a thermal film to the exterior of the flight model of the Mars Helicopter.Image: NASA/JPL-Caltech
Attaching Mars Helicopter
Attaching Mars Helicopter An engineer works on attaching NASA's Mars Helicopter to the belly of the Mars 2020 rover - which has been flipped over for that purpose.Image: NASA/JPL-Caltech
Rosetta and Philae at comet 67P/Churyumov–Gerasimenko
Rosetta and Philae at comet 67P/Churyumov–Gerasimenko Artist’s impression of the Rosetta orbiter deploying the Philae lander to comet 67P/Churyumov–Gerasimenko. The image is not to scale; the Rosetta spacecraft measures 32 m across including the solar arrays, while the comet nucleus is thought to be about 4 km wide.Image: Spacecraft: ESA–J. Huart, 2014; Comet image: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
North and South Comet Poles Compared
North and South Comet Poles Compared The northern (left) and southern (right) hemispheres of 67P. The southern hemisphere came into view in mid-2015 during its summer, which coincides with perihelion and the peak of comet activity.Image: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA/Emily Lakdawalla

This week's question:

Name the last three Venus orbiters.

To submit your answer:

Complete the contest entry form at or write to us at [email protected] no later than Wednesday, September 11th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

What does the acronym SAFER stand for in regard to astronaut-related equipment on the International Space Station?


The answer will be revealed next week.

Question from the August 21 space trivia contest:

What was the first spacecraft to take a picture of Earth from the vicinity of the Moon?


The first spacecraft to take a picture of Earth from the vicinity of the Moon was Lunar Orbiter 1 in 1966. (It was a Kodak moment.)


Transcribed by Planetary Society volunteer Jake Bathman:

[Mat Kaplan]: A comet's rich legacy, and a helicopter that's ready for Mars, this week on Planetary Radio. Welcome, I'm Mat Kaplan of the Planetary Society with more of the human adventure across our solar system and beyond. We've got it all this week, beginning with a status report on the Mars helicopter that has now been mated to the 2020 Rover at JPL. Then we'll meet two of the happy scientists who will be working with data and images from the Rosetta comet mission for many years to come. They'll give us a peek at just a fraction of that great science, and we'll finish with another What's Up segment courtesy of Bruce Betts. Most of you probably remember my conversation with MiMi Aung in our July 31st, episode the first flying machine to head for another world were still going through final testing. Now, the little helicopter has been attached to the belly [00:01:00] of that new role. Mimi wasn't available to give us an update. So we turn to Mars helicopter Chief Engineer J (Bob) Balaram. Bob is Principal Member of technical staff at the Jet Propulsion Lab near Pasadena, California where he works with the mobility and robotic systems section. Bob, thank you for coming on to Planetary Radio to give us just a quick update on the Mars helicopter project which our audience is so enthusiastic about me too, actually. Where is it now?

[Bob Balaram]: Last week we did both a mechanical and an electrical integration procedure with the Rover so mechanically it consisted of the Rover being flipped upside down so that we had access to the belly area the belly pan area and prior to that the Mars helicopter had already been integrated with its delivery system. This is the system that actually like lowers the helicopter onto the ground in a safe manner [00:02:00] from the underside of the Rover. We also electrically mated with our base station, which is the piece of the helicopter system that stays with the Rover and that's our primary interface to the rest of the Rover system. So that electrical interface consists of battery charging lines and serial communication lines that allows us to look at status and so forth during cruise and before we get deployed mating of our onboard battery to the base station charging circuits. We did a full electrical check out and then we also charged up the battery which hadn't been charged in a couple three weeks which charged it up back to a safe level so that keeps us going till the next charge point. So that was all accomplished and everything looked good. And then after that the Rover is going through its preparation for environmental testing and we will be participating in this [00:03:00] environment test... I believe it's through October. There's a vibration test, there's a system thermal test. During that system thermal test we will also be going through a deployment check out again. So that's what's upcoming.

[Mat Kaplan]: A lot of us have been following along watching the action in the High Bay there at JPL. It looks like not only is the helicopter now integrated with the Rover but the Rover's pretty much finished and very close to being ready for those environmental test.

[Bob Balaram]: Oh, yes, I believe it's... I can't directly speak for the Rover team as a whole but that's my understanding too that they're... they're all ready to go into environments right now.

[Mat Kaplan]: You have provided a good reminder of just how complex some things can be. In fact almost always are. That otherwise might be guessed it being pretty simple. The integration of the helicopter and and all of these connections that have to be made successfully for battery charging with your base station and so on. Nothing really is simple or easy when it [00:04:00] comes to space exploration, is it?

[Bob Balaram]: I think it's a matter of being extremely thorough and you know, looking through all the possibilities before attempting a particular operation. Many times you only get one chance. You don't want to jeopardize anything by making a mistake. It's not something you'd run off to your hardware store and pick up a spare part if you make a mistake. So there's a lot of procedure write up. There's a lot of scrutiny. There's a lot of peer review of to make sure that we haven't forgotten anything and then it's a very deliberate process with not only the actually the main procedure being run but there are folks from our quality assurance groups who are there to remind us, you know and make sure that we don't forget anything and the scrutinize every step. That's the way in which essentially the things get done to the best of our ability because human beings are still the weak link in the chain, but we try to minimize as much as possible, you know, the possibility of doing something wrong. [00:05:00] In the case of electrical integration procedure. I mean, there's a lot of safe to mate checking where you make sure that the, you know, the various things that are going to connect up before you connect them you take them out to a breakout box and you'll verify that resistances and measurements. And what supposed to be open is open. And what supposed to be closed is closed and you do all of this combinatorics and you verify that it meets your expectations. And then after that is when you actually like connect up, you know to cables you don't just connect up the cables and then find out afterwards that somewhere along the line something got miswired.

[Mat Kaplan]: Yeah, that could obviously be a disaster. So you're going to be busy through the testing period and maybe have some things to do right up until launch. But then what happens during that long trip to Mars? What do you, Mimi, and the rest of the Mars helicopter team... what will you be doing during that period as you know wait for entry descent and landing?

[Bob Balaram]: So right now we are getting our entire operations [00:06:00] tools in place. There are operations related to once we are on Mars. How do we select a good site from where we would conduct experiments? So there's certain requirements on our drop zone being nice and level so that we get the safest possible drop and then we have this a little landing pad area where we'll do you know do all our flight operations. TYools that we need to make sure that we find that place quickly and with safe to drop off and how do you make the assessment. So that's one set of tools. Then there's another set of tools which are all related to you know, how do we fly the system? We get downlink telemetry, how do we quickly process it? How do we give the helicopter operations team enough situational awareness as to what the helicopter has done? How do we then take the data and then, you know also like run simulations going forward to make sure that the upcoming flight is good and it's not just flying [00:07:00] it's also like things like heater set points and battery state of charge and how well is the solar panel doing? So there's a whole set of operations tools and processes where lots of boxes which need to be connected some of which which are people-type processes and others which are like more automated tools. So all of that toolkit has to be in place because once we launch we are actually into more of a training up the Ops Team and practicing together with the Rover team lot of the operation. So these are called Operational Readiness Tests, which will probably be about a year from now. So right now all the focus is on getting all the tools in place. We have built the hardware, but now it's all the operational side that we have to focus on.

[Mat Kaplan]: So plenty to keep you busy. Here's something that only just occurred to me. We all know that the Rovers on Mars have all had drivers, not that they have a steering wheel in front of them. Is the Mars helicopter going to [00:08:00] have someone or a team of people called Pilots?

[Bob Balaram]: I don't think we quite have that designation. I think since it's quite autonomous, you know, we have an operations team that will decide what the next waypoint in the sky would be and what the sequence of those waypoints would be. So to the extent that those waypoints get selected and visualized by our ground ops team, that's the extent of driving but there's nothing more than that. It's not... it's basically just making sure we get this right XYZ and sort of heading types of this that are safe and yeah in and do what we intended to do and then we'll of course have a number of operations things that are related to when do we break up the helicopter? When do we what temperatures do we set for the batteries the set point for the thermostats? So there's a lot of housekeeping kinds of things that need to be done. And what kind of priorities we give for the data we return which ones do we have a limited bandwidth overall in terms of [00:09:00] data most of the data that we get will probably be just left on the helicopter because we just can't send it all back. So prioritizing those thumbnails those kinds of things. It's going to be a quite a big team trying to run it for those 30 days of operations. So only part of it is really driving, and I won't even call it that.

[Mat Kaplan]: As we heard from Mimi, I mean you're pioneers at this, nobody has ever done anything like this before on a different world. So I'm sure they'll be a learning process as well.

[Bob Balaram]: Yeah. In fact just as much as you know, the building of the hardware and the software was a learning process, we also learned along the way how do we test such an animal that's never been built before? But the third leg which is yet to come is how do we operate such autonomous agents on another planet where it's not quite a spacecraft which is you know, in a sort of a steady state environment like an orbit or interplanetary cruise where things are very predictable nor is it like a Rover where it's almost quasi-static [00:10:00] and you can always have the luxury of sitting and thinking if something goes wrong. So here we are learning how to operate something that's in a much more Dynamic environment and also in a much more uncertain environment. So that's kind of one of the big benefits that we will get back to doing the real operations that we could never really get that full experience by just simulations or by a test program. So, learning how to operate a such a vehicle also learning how to operate such a vehicle in the vicinity of a mothership, you know, so that's going to be the other a lot of safety related things. I think overall it will be a bad finding in that sense that you know any future mission that has this kind of mother-daughter relationship between a big Rover asset and a helicopter or a future deployable system. We learn how to operate that, too. And then of course future bigger helicopters. We hope that you know with the success here will likely scale up and be sending what I would call [00:11:00] science helicopters in the 20-30 kilogram class, with one to two kilograms of science payloads, or if not more. So all will be pathfinding for that and that's why we are doing this as a technology demonstration is to learn all of this.

[Mat Kaplan]: And elsewhere too, I mean we talked with Mimi about how you were staying in touch with the Dragonfly Folks at APL who are going to send a flying machine to Saturn's moon Titan. Let me finish with this since I read that you are also an EDL, an entry descent and landing guy, are you going to be any less anxious when the 2020 Rover carrying your helicopter approaches Mars than you were when Curiosity arrived almost eight years ago? Amazing to think it was it's been that long.

[Bob Balaram]: They had their seven minutes of terror. I think you call it a seven seconds of terror when you're landing crafts. But my guidance and navigation control lead he wants to break the record for the number of landings on Mars. So he's hoping to do that with his helicopter. [00:12:00] So assuming we are successful and we don't crash he's looking to break the landing record on Mars because he thinks thaD/30 days he might get a lot more landings on Mars than anybody else. There's both a part of it that makes us anxious but I think there's part of it that new ground, new means of mobility the whole area of dimension. It's kind of like the exciting to think that the last time somebody first did a powered control flight on a planet was an earth, you know with the Wright brothers. So in some sense, it's it has that sort of feel to it. I think the team is both simultaneously excited and nervous at the same time. And I think that's the right place to be.

[Mat Kaplan]: I couldn't agree more. It is quite an adventure. I wish you and Mimi and the rest of the Mars helicopter team, well the whole 2020 Rover team, the greatest of success. We sure look forward to checking back in with you folks when that helicopter is on its own on and above the surface of Mars. Thanks so much, Bob.

[Bob Balaram]: Thank you. You're welcome.

[Mat Kaplan]: Bob Balaram, [00:13:00] Chief Engineer for the Mars helicopter project at JPL. The 2020 Rover is slated to leave for the red planet in July of next year. Planetary Radio fans probably know better than to think that the end of a spacecraft life means the end of its contributions to knowledge of our solar system and the universe. The European Space Agency's Rosetta finished its pioneering work at Comet 67p nearly three years ago in September of 2016. As you're about to hear from my next guest, the science continues to amaze with more surprises surely in store. Martin Rubin is a researcher in the University of Bern's Department of Space Research and Planetary Sciences and serves on Rosetta's mass spectrometer team. His colleague, Cecilia Tubiana, is a research scientist at the Max Planck Institute for Solar System Research in Germany and is part of Rosetta's camera team. Together they contributed an [00:14:00] article to the June Solstice edition of the Planetary Society's magazine that you can read for free on our website, That's where we started our recent conversation. Martin and Cecilia, thank you so much for joining us on Planetary Radio and thank you for contributing this wonderful article to the Planetary Report, Rosetta's Ancient Comet ESA Mission Unlocks The Secrets of Icy Relics. Thank you for joining me today.

[Martin Rubin]: Thank you.

[Cecilia Tubiana]: Thanks.

[Mat Kaplan]: Of course you are looking at some of the results coming back from Rosetta after its exploration of Churyumov–Gerasimenko or 67p as I will call it from here on out just so that I don't run into those pronunciation difficulties. It is clearly and you say this right at the top of the article it was a tremendous technical success. But you do open the article by saying it's the science [00:15:00] that Rosetta has delivered that is really its greatest success and I couldn't agree more. Really the science coming back from this Mission, it's going to keep folks like you and the rest of the Rosetta team for... busy for a long time, isn't it? Martin?

[Martin Rubin]: Yes, absolutely and we are still doing science investigations and then we keep on working on all the data that we've collected over the course of these two years. You know, the instrument was running 24/7 pretty much and then there's so much data that nobody actually has looked into so that will keep us busy for quite some time.

[Mat Kaplan]: So is it possible that there are still big or even small surprises left in that data? That just haven't hasn't been seen yet.

[Martin Rubin]: I think so. There are still a few surprises. Actually. We are still detecting new species in the ices of this Comet activity. We measured the composition of the coma for instance and we're still finding molecules and we're still [00:16:00] looking for traces of other species that might be presented nobody has seen before.

[Mat Kaplan]: And hopefully we can get into a little bit of that. Cecilia, you were part... are part of the camera team for Rosetta. Anyone who takes a look at this article, which is easily seen at, you can find the entire Spring edition of the Planetary Report there, anybody can take a look at it for free. And of course Planetary Society members receive the printed copy of the magazine. It's hard to geD/how spectacular the images are that have been returned by Rosetta. Have all of those... we may not have looked at all the scientific data yet, but have all of the images been examined?

[Cecilia Tubiana]: No, definitely not so a large majority of images have have been looked at and analyzed but I'm pretty sure that some [00:17:00] has not yet been looked at. So there are so many images or series has acquired 80,000 images during these two and a half years and I very much expect that some of these has not been looked at yet.

[Mat Kaplan]: That is quite amazing. And what a legacy for this for this mission for this spacecraft. You had over two years jusD/two years at the comet and of course science was underway, even before you reach the comet there really is nothing like being able to stick with an objecD/time it is there? Particularly in this case, right Martin?

[Martin Rubin]: Yes, absolutely. We encountered the comet when it was well beyond the three astronomical units from the Sun. So three more than three times the distance from Sun to Earth and then we followed it to its closest point to the Sun which is just outside of the Earth's orbit. And then we moved out together [00:18:00] with the comet again, and so we encountered very very different regimes in this activities. Meaning how much gas is coming out of this object and we could really follow follow this through an important portion of its orbit. Yes.

[Mat Kaplan]: We talked about this a lot with the Cassini Mission because it had so much time at Saturn certainly very true at Rosetta because as you said you were able to track it right through its highest point of activity as it as it approached and then departed from the Sun.

[Martin Rubin]: Yes, and and also if we go back to other comet missions, a very prominent example is the chalk commission which pass by Comet Haley, and the flyby speed at that time. It was huge. It was almost 70 kilometers per second. So actually the data collected there, you know, it was maybe over 10 20 30 minutes at max for the whole encounter and now here we have two [00:19:00] years of data. And also with technology that has improved since so actually the there was a big leap a big leap done in the cometary science.

[Mat Kaplan]: Absolutely. Cecilia, with so much left to learn, I mean you even say in the article that it is really no more than an overview of some of the biggest findings so far from the Rosetta Mission, but can we now say with confidence that Comet 67p is a remnant of our Solar System's formation four and a half billion years ago?

[Cecilia Tubiana]: Well comets are remnants from the solar system formation. Then how much they have evolved this depends how much they have been in the close vicinity of the of the sun definitely 67b has come in the vicinity I mean in the last few orbits, so it has evolved. That's that's clear sure [00:20:00] that the the results that have been provided by the different instruments show that 67p is a Remnant from the formation of the solar system.

[Mat Kaplan]: What was most surprising about what we've learned about the comet so far to to each of you? Martin?

[Martin Rubin]: I mean there's there's lots of spectacular discoveries. I mean the first mode maybe I'm taking this away now from Cecilia, but you know already the first pictures of the comet. I mean it was astounding that the shape the way it looked was so different from from what was expected originally. And then of course all these theories come along and how how these objects form, you know, is it a gentle collision between to commit a symbols and now looking at other comets and their nuclei it seems that this is quite a common shape. So so we are looking at the result of a process that seems to be quite common and really the Rosetta Mission brought this very much to our attention.

[Mat Kaplan]: About that shape. Can you [00:21:00] remember when someone first referred to this Comet as looking like a rubber ducky?

[Cecilia Tubiana]: Oh, well these walls as soon as we had so soon as the spacecraft crew was close enough to the commented that we could see its shape. So at the beginning when while the spacecraft was approaching it was just a dot, and then these dots start to be a flickering dot. So it was clear that the object was far from being spherical and then the spacecraft got a bit closer and then it was clear that it was something that we definitely did not expect and when we could see these two lobes was immediately called the duck shape.

[Mat Kaplan]: And you mentioned in the article that Not only was that entertaining it caught on with the public but it was useful because if somebody referred to let's say the neck of the duck people knew where to look.

[Cecilia Tubiana]: Yes exactly. I mean, it's sometimes difficult to [00:22:00] point to features on an object when when you are just talking to it but having this peculiar shape, it's easy for everyone to identify the head which is that the small part the body which is a big part and the neck which is the connection between the two. So this really helped in also in talking in describing in discussing.

[Mat Kaplan]: It is a fantastic looking object quite striking and certainly much more diverse the the surface then than I was expecting. I mean did did the diversity surprised the two of you and members of the team, or was it pretty much what you expected?

[Martin Rubin]: I think it was quite the surprise, you know, very early on in the mission. We were actually looking for a smooth spot for the lander so that the lander would certainly have both have a safe landing. Look at this object. There is no smooth spot, you know large enough that we were absolutely sure that we would not hit some boulders or [00:23:00] something else on the surface. So it was a big surprise to everybody and in the end there was of course some some risk involved for the lander but this basically shows very much how surprising or how unexpected the object was.

[Mat Kaplan]: Cecilia, there is one of the one of the images in the article also shows the comet from two sides. Basically the two poles of the comet and they are quite different. Can you talk about that?

[Cecilia Tubiana]: Yes what these images, I think the ones you are referring to a show the northern and the southern hemisphere.

[Mat Kaplan]: Yes.

[Cecilia Tubiana]: They are really different. So the Northern Hemisphere looks much more dust cover much much smoother we and it has these big peaks and these big cliffs and features. When the the southern hemisphere was then image at the same resolution so we could see we could really compare the images from the northern and southern hemisphere. We could [00:24:00] really see how the southern hemisphere inside this much more rocky it resemble like our mountains know it's much you don't you don't really see these dust cover which is typical of the Northern Hemisphere. And this was one of the very very big difference that we have immediately notice in with the southern hemisphere could be really image at high resolution.

[Mat Kaplan]: Martin anything to add?

[Martin Rubin]: It's actually interesting to look at the seasons on both hemispheres. So we have a very short but intense summer. In the South that during the passage close to the Sun, but then for the remainder of the orbit more than five years it's actually the northern hemisphere which is better illuminated but farther away from the Sun. So both hemispheres witness the much much different seasons. This is also seen in in the outgassing at the activity of this comet and so actually these objects [00:25:00] they lose mass of course all the gas or the coma as we call it this atmosphere that lost the into space. This is all ice sublimating from this object. And as this happens these objects get smaller and smaller, they lose mass, and it's actually very different in the north and in the south. This comet losses much more mass from the southern hemisphere than from the Northern Hemisphere.

[Mat Kaplan]: I'm so glad that you brought this up because I wanted to talk about the material that the comet lost as it was being observed by Rosetta how much mass was the comet actually losing to to space as it was heated by the Sun? And and of course that varied over time, I suppose as it approached the Sun and then receded from it.

[Martin Rubin]: Yes, the closer it got to the sound the more material it lost. And I think the estimate is on the order of a mill of its own mass that it lost during these two years that [00:26:00] rosette time accompanied the comet. That basically tells you there's a limited number of orbits that this comet will do before it will disintegrate.

[Mat Kaplan]: Do we have any idea how long 67p might continue?

[Martin Rubin]: I think this is actually quite difficult to say, maybe Cecilia has some more information, but it's probably not just the mass loss that is an issue. But also and that's another it very interesting result this actually we've seen that this comet is spinning up so it spin rate is going up. It's so to say the comet days get shorter and shorter. When we encountered the comet one rotation last 12 hours and 24 minutes. And at the closest point to the sun we were down to 12 hours. So the comet is spinning up and at some point it might just be that the two lobes are pulled apart because of the rotation and the associated the push in both directions of the two [00:27:00] lobes.

[Mat Kaplan]: So it could just tear itself apart?

[Martin Rubin]: Yes. That's a possibility.

[Cecilia Tubiana]: Yes, and that is most likely the cause of of the disruption of this comment rather than the loss of material due to activity. The breaking apart due to the increasing spin rate is a bigger effect than the material loss.

[Martin Rubin]: And I think Cecilia you actually see cracks in the neck region?

[Cecilia Tubiana]: Yes, there is a crack that has been seen extending. One of the very big aspect or important aspects of the fact that Rosetta was in the vicinity of the Comet of for a long time is that we had the possibility to observe different parts of the surface at different times. And so the same part a different time sorry, so we could see how the surface was evolving with time. And one of these parts was the neck the neck of the comet and one of the cracks had definitely [00:28:00] increase its size during between the two observations showing that the the comet is really evolving.

[Mat Kaplan]: An amazingly dynamic object, changing before literally before our eyes or before Rosetta's eyes. Let's switch to the interior of the comet. What have we learned about its interior? Its structure?

[Martin Rubin]: There are actually dedicated instruments to look at it. So to say to look at the interior of the of the comet, by sending radar waves between the Lander and and the Orbiter and actually the result shows that comet inside is actually quite homogeneous. So there are no extends about peak voids inside this object at least the part that they were able to sound through or to to analyze and so it seems to be quite homogeneous. Another interesting feature is actually it's very low density. So the gravity was [00:29:00] determined of the object and then from the camera you get the shape and if you have so to say the volume and its mass you can derive a density in the density is something you know, like half of what you would get for the density of pure ice. So actually it's density is very low and its porosity on the other hand is very high. So there are there's lots of empty volume but it's at least on large-scale. It's quite homogeneous.

[Mat Kaplan]: We've heard comments sometimes described and perhaps not as accurately as we thought as dirty snowballs. It sounds like 67p doesn't really quite fit that.

[Martin Rubin]: There is still ongoing discussion actually it's one of the it's an important topic actually that they're still investigating. They're still debating and not everybody agrees with each other is actually how much let's say ice and how much refractory material is in this comet. What is the proportion [00:30:00] of ice and refractory material? So whether you talk for about dirty snowball or snowy turd, or however you want to call it. That's still quite a debate. Yes. It's an important quantity. It's important to know this.

[Cecilia Tubiana]: Martin has given a good view of where we are now. Of course, Rosetta has acquired a lot of data which could help in understanding this but it's still an open question and more studies need to be done to arrive to really a solid conclusion on which is the amount of ice and dust which is in the comet.

[Mat Kaplan]: Let's talk about the ice or the water in this comment. Even if there isn't maybe there may not be as much as as what was expected has Rosetta given us a better idea of where this Comet and perhaps most are all comets get their water from?

[Martin Rubin]: Yeah. It's also a difficult [00:31:00] question because we have measurements of several different comets and in some quantities, they tend to differ and in others, they're quite similar. An important measurement that we wanted to do was to measure the deuterium to hydrogen ratio in the water. That's that's one was one of the top goals. And the idea here is that you look for these isotopic signatures of different elements. And in this case of hydrogen in the water and you compare it to for instance to Earth's to the Earth's water. Because that will give you some hints on the way to that type of comet to this type of comet could be the source for the water on Earth. If the isotope ratios are the same so the proof but it would be you know, allow the possibility that comet...

[Mat Kaplan]: One one more piece of evidence, at least.

[Martin Rubin]: Yeah. Yes, but this comet D/H as we call it ratio didn't match. But there are comets where it matched there was some confusion originally. It was [00:32:00] thought that the different families of comets there are Ort Cloud comets and then there are the Kuiper belt objects like this Jupiter family Comet 67p. And we thought, originally it was thought that this D/H depends on from which family these comments come but that basically that theory has been overturned especially after Rosetta because the elevated D/H in 67p just didn't match. That's one measurement and then one can also go and compare these D/H ratios in different molecules to the observations that have been done far away from our solar system into interstellar medium or around protostars and then you can start to compare our results with with these objects and this indicator some indication that actually the water in this object predates the formation of the solar system. This means that the water has formed [00:33:00] and it has state it stayed frozen at least part of it stayed frozen throughout the formation and evolution of this object.

[Mat Kaplan]: In other words some of this water perhaps much of it perhaps came from elsewhere across the galaxy.

[Martin Rubin]: Or basic... Yeah, I would argue that the comet is still made up of the same material like our solar system whole solar system is made from but it just has not experienced temperatures any melting or sublimation recompensation processes in the inner solar system. And actually some of the quantity some of these isotopic signatures that we see they differ from other objects in the solar system. This also gives some indication that this early solar system or where the comets formed was quite heterogeneous, it was not the same everywhere and not all the comets ended up [00:34:00] with the same quantities of different molecules or isotopes.

[Mat Kaplan]: Cecilia, while this is fascinating in itself it also brings me back to a recurring theme we talked about on this show. And that is that every time we look at a new object up close in our solar system and increasingly beyond, we learn again that they are all unique that it is a very heterogeneous universe as we look around. Do you see that as well?

[Cecilia Tubiana]: Sure, in certain aspects that's clear and in certain others, no. For instance when we saw 67p for the first time, we thought that this shape was a very unique shape. However, now that more object have been observed you can you can see the latest object of which was observed by New Horizons also shows a very bilobed [00:35:00] object which is different of course the from 67p but is not that different I would say yes objects are unique, but are maybe not so unique as we were thinking before.

[Mat Kaplan]: Yes, of course. You were talking about the Ultima Thule, that yes Kuiper Belt object that New Horizons passed at the beginning of this year. Let's go back to talking about the the composition of 67p and those most promising and perhaps interesting of compound, the organics. Were there a lot of organics found in the comet?

[Martin Rubin]: Quite a lot of organics and we looked for them in the volatile phase meaning the gases, actually also in what we call the refractory the dust mass spectrometer measured the composition of these dusts, mostly dry dust. It also contained almost 50% of organics. So organics, there's a lot of [00:36:00] organics in this object. I think it's also very prominent in camera images of this dark the dark surface. That is also often attributed to some organic residue I would call it that basically turns this object into such a dark... you see this dark nucleus and then Cecilia may be able to tell you a little bit more about this but these images that were done by the camera, they had to be enhanced quite dramatically to make all these features visible.

[Cecilia Tubiana]: Yeah, the the images of this comet look very dark so the comet in the it images looks very dark. All the all the bright patches that we see are due to ice. But overall, I mean the the the nucleus is very dark. Its albedo, it's about six percent on average which means that it's really dark object.

[Martin Rubin]: It's like charcoal.

[Mat Kaplan]: Yeah, or darker. I mean that just makes me [00:37:00] marvel even more at the success of the cameras on Rosetta because not only was this a dark object, but for so much of Rosetta's encounter, there just wasn't much light hitting the comment. Right?

[Cecilia Tubiana]: Well part of the comet was always illuminated. So the the trick is to expose the image as long as... so long enough to be able to actually detect the signal the reflected light from the surface. So the comet is reflecting sunlight. Of course, the further the comet is from the Sun the the less sunlight is reflected is. Of course also the further the camera is from the commented the longer you need to expose the image in order to see something.

[Mat Kaplan]: It just makes me even more impressed with the performance of Rosetta's cameras, along with all those other instruments and those instruments moving on here to another topic that you briefly address in the article and [00:38:00] that was monitoring the magnetic field or magnetic activity around the comet. Was that what was expected?

[Martin Rubin]: When this comet formed, magnetic field of our forming solar system actually at the location where the comet formed imprinted itself in in the material so that you have a like a magnet that the comet if the comet is actually something like a magnet because it's magnetic field of the object was coaligned with the with the outside magnetic.

[Mat Kaplan]: It's sort of gets frozen in place, right?

[Martin Rubin]: Yes, exactly. And so the idea then was with the lander and with the orbiter to do measurements of the magnetic field as the lander descend towards the comet and to see whether there is any difference of course between the two magnetometers because of of an intrinsic magnetic field of of the comet. [00:39:00] So it doesn't look that this object has any frozen in same magnetic field of at least not at the landing site, but basically also no global magnetic field. So this was really a question that required a lander with a magnetometer to land on this comet.

[Mat Kaplan]: There is in the article though some discussion of some other magnetic qualities that were found at the comet something about a different kind of field or are in a sense the lack of a magnetic field?

[Martin Rubin]: Yes. Exactly. We know that the the solar wind carries its magnetic field, but as this comet which is basically flying through this the solar wind as it gets more active and you have a scene. The first picture to activity of the comet to see all these gases coming out of the nucleus. They basically push away from the object push away this [00:40:00] solar wind and its magnetic field. And so if you get close enough to this object, then you are in a region where you are inside this bubble where the comet blows away everything that's coming in terms of particles that's coming from the Sun. And so you enter this region where no solar wind magnetic field is it's called a diamagnetic cavity. It has been observed at Comet Haley already, but here because of our prolonged stay we actually flew inside this region and out, many many hundreds of times actually. And we were able to study what happens at this interaction where it is the cometary gases dominate versus where you have also as solar wind particles and the associated magnetic field.

[Mat Kaplan]: Again, absolutely fascinating. Cecilia, I've already said that there are so many wonderful images in this article and [00:41:00] far more that can be explored by anyone and we will provide links to some of these photo archives from the Rosetta mission on this week's show page that people can get to from, but just considering the ones that you included in the article and one of the most fascinating for me is not a view of the overall comet, but of a tiny tiny area to shot of the comet's dust particles under a microscope and I thought I knew a lot about this mission, but I did not realize that among the instruments on Rosetta is an atomic force microscope one that could actually look at the smallest things that can be seen.

[Cecilia Tubiana]: Yes, there were several instruments on Rosetta and there were two in particular which would look at these small particles. So one is MIDAS and the other is Kojima. I think the image you are referring to is the one that was [00:42:00] taken by Kojima. Which shows so how it's working is that Kojima had an aperture and the particles were entering inside the instrument and sticking on the on the target. In this image, you can see how we have different types of particles. So the Kojima team has categorized them in four types according to the which are the the properties once they have sticked on the target. So you can see that there are there was this type A particle which stayed which look like stays more compact while the others are more, they got like more destroyed when they have impacted on the on the target. And so this was then used to characterize which are the properties of the dust which is making up these particles.

[Mat Kaplan]: So we are learning more about Comet 67p at every scale [00:43:00] from the microscopic to being able to examine this entire beautiful object in one image. You close the article by mentioning that NASA is considering a sample return mission for this Comet 67p I bet that's a mission the two of you would love to see.

[Martin Rubin]: Well, I think by now actually NASA selected the competitor, so it's not going to be this comet, but hopefully we'll get another chance at the comet that the sample return mission. I think especially for the task community this is of course something that has to be done. I think it's a little bit more difficult to bring back some of the highly volatiles because this would require a very very low temperature for the return trip and also the atmospheric entry and the pick up until I think technically that's a [00:44:00] that's a very very challenging one. But already in the dust it is all maybe some of the organics we talked before. This will be very interesting if they're not very volatile then we could bring them back. We've seen a lot of very interesting organics including glycine. Which is actually the simple most amino acid finding this on a comet that certainly devoid of any life I think this is quite fascinating.

[Mat Kaplan]: Thank you for the correction. First of all, I'd forgotten that the comet sample return mission that basically was eliminated because of the selection of the dragonfly mission to Titan, I'd forgotten that that was the one that would have gone to 67p. Cecilia, what about your feelings? What would you like to see happen next in our efforts to understand comets and and therefore our own solar system?

[Cecilia Tubiana]: I think that Rosetta [00:45:00] has definitely increased our understanding of comets and our understanding of the in a way of the solar system. However, it has opened a lot of questions and left and also left the many questions still unanswered. So definitely Rosetta is not an end. Point on the on the study of commitment is the starting point. So having more missions or New Missions studying comets is definitely important. And as Martin was saying having a sample return Mission which brings back volatiles is very it's very complicated still at least having a sample return mission that brings dust that that would be would help to to answer to some more questions compared to what Rosetta has answered so far.

[Martin Rubin]: There's pros and cons of going back to the to the same object and given that all these [00:46:00] comets are to some extent similar but in a not on the other hand death vastly one from another and actually the sample of objects we have visited. I will be in very much in favor of going to to another object that we haven't had the spacecraft close by before or potentially, you know the next time when Comet Haley returning we could consider actually doing another visit at Haley.

[Mat Kaplan]: Wouldn't that be something to have a mission like Rosetta at that most famous of comets that could stay with it as it makes its journey around the Sun.

[Martin Rubin]: Yes, that will be great. Technically, it's it's extremely difficult because Haley is moving opposite to the planets. So to say it's a moving a counter direction of all the planet so actually getting on [00:47:00] its orbit is pretty much impossible. Unfortunately.

[Mat Kaplan]: I have no doubt though that with the amazing success of missions like Rosetta somebody out there could figure this out.

[Martin Rubin]: Let's hope so.

[Mat Kaplan]: In the meantime though. It sounds like both of you expect to remain very busy working with this data much of which is you said, is yet to be examined from the Rosetta Mission?

[Cecilia Tubiana]: Oh, yeah, definitely in this year's is no doubt that also for the images for instance. I mean many images have been analyzing and big big discoveries have been done but there are still many more details that have to be understood or which could be understood and definitely the data that Rosetta has provided are the best data about the comet for the next decade. At least. This will be the the subject of studies of the next generations, I [00:48:00] think.

[Martin Rubin]: Actually putting a lot of effort in putting together or archiving all these data and to make it available to the community. There is there are research projects. There's actually a data analysis program by NASA where you can apply and you can use the data archive to do your own science investigations. So it's not that the data is just with us, but actually it's it's publicly available and I think that's. That's also the goal to make this available for a whole lot of scientists to look everybody brings a little bit of a different turn away front twist and has a different experience and actually bring this all together is very much to the benefit of the mission.

[Mat Kaplan]: Exciting science. I wish you both the greatest of success as you continue to work with this data from Rosetta and learn about its origin and and perhaps our own origin as [00:49:00] well.

[Martin Rubin]: Yes very much. I mean they're really looking into this again the organics, you know, that's a yet another another question. We figured out that that type comet is maybe not the major supplier of water on Earth. On the other hand, it could be a made... It could be a significant supplier to the terrestrial atmosphere, through impact parts of the atmosphere might be of cometary origin. But then also a lot of these organics arrived on Earth maybe a little bit of comet is in knowing everything in all of us.

[Mat Kaplan]: I like that. Cecilia, you sound like you do too.

[Cecilia Tubiana]: Yes. Sure.

[Mat Kaplan]: Well, thank you both. Once again both for joining us today on Planetary Radio, but also for this excellent overview of the Rosetta Mission and the science that continues to pour from it and I do wish you the greatest of successes as your work with this data continues. Congratulations to you and the [00:50:00] entire Rosetta team. It's hard to believe that it has been three years since the end of this mission but in so many ways, it seems to live on.

[Martin Rubin]: Yes. It's it's it's living on and then it's really as you just mentioned it's it's the work off of a big team. And it needed a lot of expertise in different fields. And I think Cecilia I are just lucky that the, you know could give this interview but it's actually on behalf of a big of a big team. Thanks for having us.

[Cecilia Tubiana]: Yeah. Thanks to give the give us the possibility also to show to more people how how successful Rosetta has been and how much more can be can be understood from the from the wealth of data that Rosetta has collected. As Martin was saying the data are not only for the science teams, but for are really for everyone so really everyone is welcome to go to the to the [00:51:00] archive and and look at the data and even just just look for the fun of looking at how a comet is or just to also to analyze the data into to give his or her own viewer opinion on what Rosetta has has seen.

[Mat Kaplan]: Again, we will provide links to that data images and other science from Rosetta on this week's show page is where you will find it. You are both most welcome. It has been a pleasure. And of course this is this is why we do this show so that we can talk to folks like you and share in the excitement and discoveries that you're making my guests today have been Martin Rubin who is a researcher in the University of Bern's Department of Space Research and Planetary Sciences. And he serves on the Rosetta mission's mass spectrometer team, and Cecilia Tubiana, who is a research scientist at the Max Planck Institute for solar [00:52:00] system research in Germany and is part of Rosetta's camera team. Time for What's Up on Planetary Radio. Bruce Betts is the Chief Scientist of the Planetary Society. He is back to tell us about the night sky and maybe take us through a few other things. I had a bunch of people here was sort of a fundraising thing. And two telescopes out and of course, it clouded over moments after we took the telescope's out so we didn't get a chance to look at beautiful Jupiter, but I know it's still up there.

[Bruce Betts]: That's a well-known scientific effect. Pull out the telescopes and it would cloud over or just take me to your observatory and it may have a similar effect.

[Mat Kaplan]: Bruce's Law.

[Bruce Betts]: Okay. Yeah, exactly. So yeah Jupiter looking lovely when you don't have clouds or fog over in the Southwest in the early evening brightest star like object up there. And to its upper left kind of over to the left more to the [00:53:00] South to Saturn looking yellowish would have been lovely through your telescopes and it's hanging out just a little above the Sagittarius and I'll once again encourage you to look for the teapot shape of Sagittarius if you haven't before. We move onto this week in space history. 1977, Voyager 1 launched. Still working.

[Mat Kaplan]: I keep saying it's several weeks now I've been saying we've got to get Ed Stone back on the show for an update, but I'll get to it. I promise.

[Bruce Betts]: 2016, a little more recently, OSIRIS-REx launched, but also very successful hanging out at asteroid Bennu right now. And of course, I like to mention for you every year, 1966 a great year, Star Trek debuted.

[Mat Kaplan]: 53rd anniversary of that show and who still with us? The Shat. Shatner himself.

[Bruce Betts]: The Shat. We move on to Random Space [00:54:00] Fact.

[Mat Kaplan]: Was that your rendition of the Star Trek theme?

[Bruce Betts]: Yeah?

[Mat Kaplan]: Yeah, fortunately you didn't pass that audition. When when you audition for Gene in 66.

[Bruce Betts]: Yeah. I know the my sons are the singers of the family, obviously.

[Mat Kaplan]: They're very good.

[Bruce Betts]: Moving on. If Chandrayaan-2, which is in lunar orbit right now lands successfully in the next few days. So keep an eye on the news including, it would make India the fourth country to soft land on the moon after the US, Soviet Union, and China.

[Mat Kaplan]: And more power to them. I sure hope that works out. It's going to happen Friday afternoon Pacific time and I would love to think they'll be some kind of live coverage coming from the Indian Space Agency, ISRO, but I haven't heard about that. We'll have to check it out.

[Bruce Betts]: We'll find out but in any case kind of exciting.

[Mat Kaplan]: Yeah, very. [00:55:00]

[Bruce Betts]: Speaking of exciting we go on to the trivia contest. I asked you what was the first spacecraft to take a picture of the Earth from the vicinity of the Moon? How'd we do, Mat?

[Mat Kaplan]: I will answer with a poem, a little Limerick, not from the poet laureate this time who I was taking a taking a break, but from David or Dave Dolphit whose name I have been mispronouncing it when he comes up here, Charlestown, West Virginia. Way back in 1966, something new was in the mix. NASA sent a probe to space. Took a photo of Earth's smiling face. While it was orbiting around old Luna the probe was lunar orbiter una. Lunar Orbiter 1, right?

[Bruce Betts]: Yes, Lunar Orbiter 1. That is correct.

[Mat Kaplan]: Here is our winner. Chris Goeddy, or Getty, of Delphos, Ohio. He said sure, yeah, it was Lunar Orbiter 1, which was sent [00:56:00] out there to sort of scout the surface for the Apollo Astronauts and the surveyor Landers, right?

[Bruce Betts]: Yep, give us all sorts of groovy pictures of the Moon.

[Mat Kaplan]: Well there were a bunch of people, first of all, who were surprised that this was actually done with film, good old-fashioned film, was shot by lunar orbiter developed and then finally scanned in an analog fashion.

[Bruce Betts]: Yeah. That's why the original versions you see stripes from the scanning process.

[Mat Kaplan]: You're old enough aren't you to remember the old photo booths, pre-digital, that actually there was one that was like a see through a transparent one at the old Museum of Science and Industry in LA and you could see the film being dipped into... simulated actually because you couldn't they couldn't put the light on it, but see the film being dipped into these various solutions to develop the film. It was just fascinating. But it was only a couple of people [00:57:00] including Norman Kasoon, in the UK, regular, who reminded us that the camera to do this came from Eastman Kodak and was actually developed by the National Reconnaissance Office in the US to be flown on spy satellites. Boy I Miss Kodak I miss Eastman Kodak, what a great company I know they're still around but there are shadows of their former selves and they were such a great company.

[Bruce Betts]: Yes. Yes. I use Kodak film for very very long time.

[Mat Kaplan]: When you did your stuff with big big big telescopes where they still shooting film or was it already digital by then?

[Bruce Betts]: By then it was digital. It was the the astronomical community lead the way with that or at least for one of the entities, so they were doing digital CCD detectors before they were in the commercial market by a few years.

[Mat Kaplan]: I mentioned it only because I know Kodak used to treat scientists well because you know film was needed for all kinds of things including astronomy, and [00:58:00] and that was just one of the great things about the company. Oh well. I got one more for you to nothing to do with the contest really, but it's from George Sonnier in Louisville, Kentucky, who has been listening is one of these crazy people who spend listening to old Planetary recording started back when the show started, 2002.

[Bruce Betts]: Would you stop calling them crazy?

[Mat Kaplan]: He says I got to tell you compared to those old recordings you and Bruce sure have slowed down in your old age. But then George remembered that he's been listening to the old episodes at one and a half times speed.

[Bruce Betts]: I guess the new ones are exciting enough he doesn't need to do that.

[Mat Kaplan]: No, I guess not. There must be some people out there who you know like to listen to us at 10 times speed. Just to get it over with, you know? I'm being so cruel today including to...

[Bruce Betts]: You're so cruel to the show.

[Mat Kaplan]: Take them take us to another [00:59:00] cruel contest to do a cruel contest to a cruel world. Name the last three Venus orbiters. Go to

[Mat Kaplan]: By the way, I neglected to say that our winner Chris this week is getting some of the stuff that somebody's going to get that next week as well. He got a priceless Planetary Society kick asteroid rubber asteroid, which we're not awarding this time. We're replacing that with a Planetary Radio t-shirt, the latest and greatest design its back. A 200-point astronomy account, that great astronomy service, which is now working with this new image processing system. It's integrated into iTelescope and I've seen some of the before and after shots that amateurs have been getting them. It's really very impressive. And both to the current winner and the person that will win in two weeks a copy maybe a signed [01:00:00] copy of Bruce's super cool Space Facts, a fun, fact-filled space book for kids big day for you, right? It's officially out as we speak.

[Bruce Betts]: It is big day very exciting. It's out and available on Amazon.

[Mat Kaplan]: And it's a published by Rockridge Press. You can win one if you get picked, I think we're done.

[Bruce Betts]: All right, everybody go out there look up in the night sky and think about your favorite wind direction. Thank you and good night.

[Mat Kaplan]: He's Bruce Betts the Chief Scientist of the Planetary Society blows in like a nor'easter every week here for What's Up? By the way, the deadline for this week's contest is Wednesday, September 11th at 8 a.m. Pacific Time. Planetary Radio's produced by the Planetary Society in Pasadena, California and is made possible by its sail-powered members. Mark Hilverda is our Associate Producer. Josh Doyle composed our theme, which was arranged and performed by [01:01:00] Pieter Schlosser. I'm Mat Kaplan, Ad Astra.