Auld Reekie Astro Whats Up Podcast Episode 38

Auld Reekie Astro Whats Up Podcast Episode 38


[Music] Martin: Welcome to episode 38 of the Whats Up podcast recorded by Auld Reekie Astro Martin: today’s the 27th of June 2019 my name is Martin Ali: I’m Ali
William: And I’m William M: so today we’re gonna discuss a few stories that have caught our eye, all based around our sort of back garden as we’re gonna refer to it. In this case though our gardens gonna stretch out quite far into the Solar System. So we’ve got
three topics to talk about, let’s start off with Ali, what do you want to talk
about today?
A: I want to talk about Uranus A: Excellent.
M: Glad that’s out the way A: You’ve got to acknowledge that
moment just once but there was a recent story that just popped up just last
week actually about somebody’s taken a new observation of Uranus’s ring systems
and for those of you that aren’t aware Uranus is the second outermost gas giant
and it’s technically an icy giant because Uranus and Neptune together are
made of more ices than are Jupiter and Saturn so they’re technically in a
different class they’re about four times wider than the earth and Uranus is weird
W: That’s a bit harsh
A: Well, there’s lots of weirdness about it so it so it’s always interesting when
somebody does something new but they’ve pointed ALMA so the
submillimetre instrument in Chile they’ve pointed it at Uranus to study
it’s ring system for the first time so this is actual thermal emission from the
ring particles and everyone’s familiar with Saturn’s rings and they’re quite
well understood because we’ve had Cassini doing a very good job of imaging
that from multiple angles and it turns out Uranus’s rings are also weird and
particularly the brightest of these rings and it turns out that it’s a
little bit warmer than they were expecting and they’ve got evidence that
there’s not a single bit of dust in the rings or a tiny amount of dust because
of the observations that they’ve got and that’s a little bit weird
because just about all the other ring systems that we know of have
very dusty small particles all the way up to you know bigger boulders and maybe
even house sized things in the case of Saturn’s rings but Uranus’s one seems to
be centimeter sized and up for this particular ring which is interesting
because it needs it’s another thing to solve why why does it not have any dust so it’s quite a wee story but I thought it was interesting because
Uranus is full of things that we still don’t understand
W: It’s kiffed isn’t it?
A: well it’s it’s
W: technical term M: What do you mean?
W: it’s on its side
A: It’s rolling aboot on it’s side. Kind of like a it rolls like a barrel
W: yeah
A: whereas a lot of other things are rotating with the equator of the planet
M: ok
A: pointing towards the Sun
W: like everything else is M: so rather than like our planets
rotation axis being quite well aligned so that it goes in kind of in the same way as it goes round the Sun we’re saying that Uranus is leaning over on
it’s side W: yeah kiffed
M: going at a strange angle so yes
kiffed as you were going to point out W: yeah so I think something silly that it effectively means one side
has continual daylight, well who doesn’t A: would you like some stats about Uranus
42 years for each pole
W: 42 years for it to precess A: 42 years in sunlight and then 42 years
of darkness if you’re on one of the poles
W: a lot of darkness
A: quite a cool stat it’s also the coldest place in the Solar
System that we’ve measured with probes so M: I’m so gonna call you out on that one
because that’s actually not true the coldest place in solar system we have
ever seen is on Earth
A: really?
M: because in the labs we’ve created spaces that are
W: nerd
M: far colder than anything else A: you are splitting hairs M: similarly the hottest place that
we’ve ever measured in the Universe is inside the Large Hadron Collider during
a collision so
A: I think I may have to give you that
M: coldest naturally occurring place that we’ve spotted A: can I just call it the second coldest?
M: that’s fine
W: which also is that might be the coldest place in the Universe not just the Solar System when
because unless there’s another intelligence species who are doing a similar thing which I mean it might be but it’s arguably the coldest place in the whole
damn Universe pretty exciting A: I’m a little bit nervous I have opened a can of worms here
W: you have sorry
M: it’s a little off topic—
A: but it’s interesting because it’s cold it shouldn’t be the coldest. Neptune’s
further out Neptune should be colder they’re both icy giants
why does Uranus have less internal heat coming out of it
W: smaller?
A: they can’t find there’s hardly any extra heat coming from the
inside so even the Earth radiates more spare heat than Uranus does and it
basically radiates all the sunlight that falls onto it straight back into space
but there’s no hint that there’s extra heat coming from the internals
of the planet whereas every other planet that we can measure this for, you do see
a little excess maybe from decay or heat in the core or radioactive elements but
there’s a little bit of something and for some reason we don’t see that at Uranus and that might be to do with the fact that it’s been knocked on its side
W: yeah so the knocked on this side thing I mean could that be linked with why this ring
structure seems different other ring structures I mean
A: I guess the short answer’s yeah?
W: I mean like Saturn we think that the ring is from a disrupted moon or
something like that
A: yeah and so you need to figure out why there’s no dusty bits
so is it fresher than some of the other ring particles they haven’t had a chance
to collide and smack into each other enough W: or the other way around?
A: or is it arguably older and something else has come through and cleared the dust away or all the dust is congealed onto the bigger
bits you know so it’s lots of interesting stuff
W: and so it’s worth saying this was seen with ALMA which is as you say is a submillimetre telescope so
it’s looking at things which are wavelengths of light a little bit shorter
than a radio telescope
A: cold stuff yup W: and this measures dust generally doesn’t it? or small cool-cool particles A: yeah well they’re comparing it with optical sorry infrared observations with VLT and the comparison allows them to go does not
there’s hardly any dust because the they’re getting the same sort of color ratios
from the submillimeter as they are from the infrared and you would expect the
infrared to be squelched if there was a lot of dust there
W: ah yes
A: because I guess the submillimetre
should pass through all that but because you’re seeing sort of the same thing it
means there’s hardly any dust interfering with that extra light so
it’s just another one of these things where you can’t
W: what? weird
A: this is the problem with Uranus there’s not much data on it and W: we’ve only been there once
A: we’ve only had one probe and everything else you’ve got to do Earth-based and what’s quite nice is once Webb Telescope is up and running it’s
probably gonna have some science to do pointing at the gas giants
and that includes the icy ones so we will have slightly better data this time
in the mid infrared and maybe some of these answers will get solved I think
the best theory for why it’s weird is that it’s been smacked into at some point
in the past by something bigger than Earth and that’s one of the reasons why
it’s strange and you can see that in some models but I don’t think I
think the jury’s still out on exactly what’s going on
W: yeah and getting there is quite tricky
A: little bit
W: actually asked a possible kind of tease for what we’re about to talk about the orbital dynamics of it are kind of intriguing because we’ve only
been there once as you say which was Voyager 2
A: 2 with the Grand Tour which you
can’t do for at least another 60 years or something I think
W: flukily aligned
A: everything’s lined up yeah
W: where we’re sort of whizzing by but part of the and worth highlighting as well that’s even forty years ago thirty-something years ago now so I’m sure it was a phenomenal spacecraft
it is but the detectors and equipment which was there it’s not quite the same
as the sort of things we’re now getting those high-definition images coming back with
Juno but the other thing is that because of the orbital dynamics it’s
really hard to put something in orbit around Uranus isn’t it I think that
you you’ve got to get up so much speed to get there in a sensible amount of
time that you then you probably need some fuel to break and slow down to get
yourself into orbit but if you got to take fuel then you’re more massive
and it becomes a real nightmare I think one of the reasons why it hasn’t been
done by I saw a paper discussing it trying to talk about plan you know crazy
missions where you could do it but it was going to be a really difficult thing
M: there’s the same reason why New Horizons didn’t do a orbit of Pluto it was going so
fast to get there in a reasonable time you have to swing past you can’t stop and slow down
A: it’s almost like the first question you have to ask to flyby or not to flyby
M: yes
A: that is the question so yeah far away things I think you’re better off with
flybys
M: and I think that leads us really nicely into a different story
so William what story is this
W: indeed yes it does lead us nicely to the interview
which we recorded earlier with a very important person who works on the site
here at the ROE with us so we are lucky to be joined by Colin Snodgrass today who is
the deputy lead of the Comet Interceptor mission which has just been
accepted by ESA I think I’m saying that right aren’t I?
Colin: yup
W: you’re nodding
C: yes
W: which is a good sign what’s all about?
C: so this is it’s fairly
well it does what it says on the tin so Comet Interceptor is to go and fly past
a new comet so the way that you can go and visit a new comet coming into the
Solar System for the first time is to go and build a spacecraft that will loiter in space and wait for it
W: loiter in space
C: yes
W: that’s good I like that because the problem is with these comets
is then they’re coming in and normally we only discover them sort of
months to years in advance and it takes a decade or so to plan and build a
spacecraft so to try and meet a new one coming in you’ve got to build the
spacecraft before you know the target launch into space and then wait for a
target to come to you so this is what this mission does which is kind of
different from anything we’ve tried before W: so what are the kind of time
frames you have to wait I mean how long does this thing loiter? or where does it loiter for starters I suppose?
C: so it’s it’s meant to launch in 2028 and it so
it launches with the ARIEL Space Telescope which is a ESA telescope to
look at exoplanet atmospheres and that’s going to go to the Sun-Earth L2 point so
the Lagrangian point which is where the gravity of the Sun and Earth balance out
and you can park in space with very little fuel used
W: this is the same place as JWST
C: yeah that’s why JWST is going it’s where ARIEL’s going it’s a busy patch of space
A: a gravitational sweet spot
C: exactly so it’s a it’s a good place to park in space so
it’s why you put telescopes there it’s where Herschel Space Telescope was and so you
can put a whole bunch of things there and one of the things we’re going to put
there is Comet Interceptor which is going to just kind of yeah hang out there try not
to crash into JWST and ARIEL and all the other things that are loitering out there and then it
can wait there for a few years basically so the the main driver on how long you
can wait is is building your spacecraft to survive in space for not too long so
they’ll be designed to be operating for about five years so that’s a few years
waiting a couple of years after leaving L2 cruising to intercept the comet
and then a couple of days of actual science as we go flying past a comet
really fast
W: so it’s took nine years of planning five years of loitering two
years of traveling for a couple of weeks
C: couple of days of encountering a comet in which all of
the the juiciest data is a couple of hours of right around the closest
approach because it’s a really fast encounter yeah this is one of the things
if you’re coming if you’re going to a comet that’s coming in from from the
Oort Cloud or coming in from potentially even from outside our solar system these
things are going really fast relative to you so the this thing’s gonna be tens of
kilometers a second up to maybe sort of 80 kilometers a second in the worst case
if it’s some retrograde comet that’s orbiting the Sun the opposite way round to
we are because then you meet them really really fast
W: yes
A: sounding quite dramatic can I can I just check because this is quite timely that we
have you here so are you even still hungover from the
official announcement because we should we should probably explain how all this works I mean
C: yes so we only got told this last week and Wednesday last week
so it’s what a week now that we’ve known about this thing and and yeah so already
well yeah a couple of days of frantically emailing everyone and going
and talking to various press things and so on and then we were already started so I’m
back today in Edinburgh from yesterday I was at ESA’s headquarters in in ESTEC in
the Netherlands where we’ve already started the design process so I spent
yesterday talking with these engineers about you know how we actually gonna
make this thing work and because they kind of take our our proposed plans and
then tear them up and start again from scratch and say okay they said we’re
really going to do this and so yeah there’s an ongoing process at ESA at the
moment to kind of redesign this whole thing from from from basically from
here’s the science requirements and instruments we need let’s make this work
A: I like it so the minute the green light comes in you’re like right it’s time to get to work
C: it’s go go go yeah so this is the first F-class mission from ESA which is fast class and they you know we were all sort of joking okay fast
for ESA so okay it’s only nine years but I mean they really they mean it they were
you know yeah they were you know well done you have a mission and now go and book some flights
A: they’ll always be looking at you from the corner of the room
tapping their watches and going mm-hmm C: yeah exactly it’s like you know what do you mean you still haven’t figured this bit out yet no on you go so
yeah so it’s yeah it’s gonna be exciting W: I mean it’s actually it’s a quick
turnaround isn’t it really
C: it is
W: nine years for planning and getting ready your space
mission actually
C: yeah
W: it sounds a long time but by space standards it’s really not
C: it’s really it really not especially because you know that the way
that ESA does these things so yes we kind of designed this whole mission and
wrote a proposal based on some you know this is how it should work and had to
write this in a convincing enough way that it looked like it would work and we
had some support from kind of space industry companies who build spacecraft
and said yeah no this will work A: can I ask how long ago you know when did that
process start and were you there from day one kind of thing?
C: yeah so in this case it’s also only been a year or so since they they actually put out the call for this
A: wow
C: and announced that was this opportunity
W: so it’s fast
A: 10 years from back of envelope to actual mission launch
C: yes exactly so there’s yeah we had about this time last year a call went out with first
deadline for outline proposals would have been kind of late summer last year
by Christmas time they’d kind of whittled that down to six proposals that they
thought okay this sounds interesting and asked each of those teams to prepare
more detailed proposals so that’s when you went and you know you spoke to
someone that knew about actually building spacecraft and you kind of wrote a 40
page or 50 page detailed proposal and then from that one they’ve now selected
one and yeah now we go into a sort of initial design study with ESA and their
engineers for rest of this year or so next year they’ll kick off another
detailed study with space industry who’ll spend a couple of years designing
alternative versions and then finally they’ll pick the version they like
A: okay I’m saying this is this is a silly question but I have to ask it did they
have any pomp or circumstance when they award a mission you know is there like a moment
W: Oscars
A: where they give you a red rose? C: it was this was there was basically there was a panel meeting with one of the sort of senior committees in ESA last week
who were who were deciding on this and essentially we got an email going well
then it’s yours about the same time as they they announced that to the world
and they put it on the you know this nice article on the website’s like by the way you’ve got this
and then it’s like oh good and then you know immediately start tweeting like
crazy and you know
A: I saw some of those yes C: yes
A: makes it nice that we’ve got you here who’s your partner in crime by the way sorry that I’ve forgotten who you’re
C: it’s Geraint Jones at MSSL which is part of UCL in London who’s the who’s the lead
proposer and me and then there’s a team of people
from well all over the world actually because we’ve got this whole European
team that’s leading it but then the this mission is also joint with the Japanese
space agency JAXA so there’s a large group there and there’s some folk in the
States as well we’re working through NASA to contribute one of the
instruments so it’s quite a kind of international plan
W: so the fact that it’s
kind of a fast mission does it mean you can be more risky than other missions might be?
C: in some ways I mean we overall we can’t but one of the things that we’re
doing with this particular mission is so we have the spacecraft that waits around
at L2 and then goes on flies past a comet just before it gets to the comet it
will release a couple of smaller probes or sub-spacecraft and so the main
spacecraft will have a you know reasonably safe distant flyby of the
comet about a thousand kilometers or so from the nucleus so still well within
the coma and the gas and the dust of a comet but not in the most kind of
dense part where there’s most danger but it will release these couple of
probes that will go a bunch closer they can take a punch they can take more risks
so they are designed to you know they should survive but it’s not mission
critical that they do so they’re transmitting data back to the main
spacecraft and if all the way in and yeah if they don’t make it out the other
side then the mission still succeeds
W: yes A: are you aiming to ultimately orbit the
comet or do you only have a flyby chance it’s just it’s just a real fast flyby so
there’s no way we can match speeds in orbit like we did with Rosetta A: because you don’t have the time to
C: we don’t have the time and most mostly we don’t have the fuel to do this so they with Rosetta which is a
short period comet it takes six years to go around the Sun the spacecraft
could spend ten years kind of orbiting doing flypasts of a couple
of planets and building up speed to match the the orbit whereas for a long
period comet like this that’s coming in at high speed there’s just no way we can
do that
A: so how do you how do you choose right say you get one that’s got a non
optimal trajectory and you’re kind of like right on the margin of whether or not we
can do this who’s the person whose weight that will be on for the yes or no
thumbs up thumbs down for lighting the candle C: so there’ll be there’ll be
a few of us that are making this decision no probably won’t leave it to one person
A: flip of a coin
C: yeah so there’ll be an ESA engineer team who will you
know say whether or not they think it’s it works as possible and they probably
won’t let us do anything too crazy because they tend to be more responsible
people than scientists and then there’ll be a science team kind of going ooh, that
looks like an exciting one or this one so in an ideal case you’ve got a two or
three comets potentially to choose from in the period you’re waiting
A: do you also have to list you know all the various things that you want to see happen for
criteria that you’re looking for so this kind of speed and this kind of trajectory
yeah I mean I think that largely it’ll be we’ll pick the one that works and as
soon as we find one that we know works we’ll probably go for it but I mean there’s
there’s probably a long period between discovering it and kind of before you
actually have to yeah fire the rockets and go so you can kind of keep
an eye out for does something better come up in the meantime but yeah
A: are you allowed to jab other telescopes in the ribs for some help to help classify
C: I imagine we might be doing that a bit so that we kind of one of the nice
things about this the time scale of it is that it’s come we will have the LSST
survey coming online next couple of years and this is going to find so many
more things of every type so it should you know almost certainly it will be
the thing that discovers our comet and then it will keep going in survey will
get quite a lot of data from the from it anyway just from guess just from
from on the ongoing survey but probably we’ll also yeah be then running proposals
for everything else to say okay we want to characterize this we want to go and
look at it with JWST before comes in we want to go and you know
A: very exciting
W: so you mentioned some of the an interstellar thing so ʻOumuamua type
objects which came from another system yeah a possibility?
C: it’s a possibility yeah in terms of intercepting something there’s not that
much difference between interstellar object and an Oort Cloud object in terms of you know sort of speed it’ll be coming and so on the big difference is likely to be well two main
differences firstly there are going to be more Oort Cloud comets coming in we think there’s a much higher probability we’ll get one of those within the time frame
that we can reach but the other thing is if if all interstellar objects behave
like ʻOumuamua then they don’t have this big coma they don’t have this
activity they don’t have the tails of a comet so you don’t spot them as far
out so that the you for the same size of object you can see a comet coming much
further away than you can see something that behaves like an asteroid
just because it has a much bigger reflecting area you’ve got all of the
coma so we’ll have you know many years warning with LSST of an incoming
Oort Cloud comet and that’s time to fix the orbit you know take these
observations to characterize it be sure that’s the target you want calculate and
recalculate the trajectory and you know be sure of all the numbers and go yes
definitely that one make a decision where is if it’s something like ʻOumuamua
that we have you know only weeks it’s really having to phone up someone at ESA
in the dead of night and go right go go go fire the rockets that will make ISA more nervous
A: will you have to sneak up in sort of automated fashion whether the probe itself is doing there that’s where it is and sort of refining things given the distances involved
C: yeah so on the you know on approach we’ll be able to use the the cameras on board to sort
of see the comet and refine the trajectory a bit in the kind of months
and weeks leading up to it but at the very fast bit the very end for the flyby
it’ll have to kind of automate autonomously track the the comet as it
swings by just because the everything happenes so fast there’s no
way to command that from Earth A: I think was it one of your tweets where you suggested can we can we have some more shiny cartoons from ESA please
C: yes
A: for those of you that aren’t aware the Rosetta mission had some really pretty
cartoons where they sort of anthropomorphised the lander and the
orbiter and I would love to see more of those so I would hope that would be true
C: yes yes well I already spoke to the people responsible for the Rosetta
cartoons they are also very keen on doing more comic cartoons so hopefully that will happen
A: very cool does it does the name change at any point now
are we to call it Comet Interceptor for the time being
C: it’s Comet Interceptor for now we might may at some point rename it or potentially name
the individual three different spacecraft that make up Comet Interceptor they might give them names at some point but we haven’t done that yet
W: it’s a good name because it’s a name which tells you what it is as you say it’s like so often the names are
completely random and disconnected so M: yes but in the same token if you can get
to command the Snodgrass Comet Interceptor you know I’d be pushing for that one
C: yeah I suspect Geraint might have some words to say about that but yeah you know
A: very cool
W: well thank you very much Colin, that’s awesome to hear about and hopefully find out
more as you as the design sort of crystallizes and good to talk again
C: yep well it’s a long process from here so many chances to talk again about this as
we go ahead
A: yeah good luck
W: cheers C: alright thanks
M: thanks again Colin for joining us for that interview I’m sure it’s something we’ll hear a lot more about in the press and as well something we’ll have a chat with him over lunch on a regular
basis all the trials and tribulations of a fast track satellite mission it’s
gonna be a real challenge okay I think we got one more story
I just wanted to quickly highlight is one that I spotted in the news and which got a
fair bit of press and inches column inches I suppose which was that Curiosity the Mars rover has detected a methane spike and what the implications of this
might be and a bit like the Uranus story getting lots of press coverage
for something that I don’t think’s that necessarily a lot to say about it I fear
this is a little bit of the same thing W: well it is interesting and bizarre it’s just the fact that it’s got a very tenuous link to life
M: yeah
W: means that whenever it gets
A: dun dun duun
M: yeah this is this is Curiosity who has detected a spike of methane gas so a big
plume by the standards of plumes of methane that is detected previously on Mars so quite a big one it’s like 18 parts per million now the Earth’s
atmospheric concentration of methane about eighteen hundred parts per million
of methane so okay firstly just adjust that parameter so we’re not saying like
it’s discovered a swamp full of bacteria on Mars that’s not the case but it
has detected a weird spike and also this could just be some something else it
could be a geological process it could be old it could be new could be lots of things that happened that’s released this pocket of CO2- of methane but it might not be
a bacteria fart
A: how do you ever convince yourself it’s one thing or the
other is that you know is this being this isn’t the first plume Curiosity’s
seen I don’t think
W: no I think but it’s the largest
A: it’s the largest okay so
at some point if you see enough large ones does that convince you that it’s not geological
W: no I don’t think it can
A: but you might never be able to answer it completely
W: no but I think the thing that is really intriguing I don’t think anyone was expecting it is that it hints a very
dynamic system in that as you remember there were early measurements which were
taken from an orbiter which hinted at higher levels of methane and then
Curiosity’s first measurements went no not that high and then actually suddenly
you get a plume and it seems to vary it seems to be changeable which suggests
that whatever is there is not it has been generated recently I think because
I think it would be I think they expect it would be more evenly distributed throughout the atmosphere and you wouldn’t get these kind of bursts if it was a if it
was an old reservoir so that’s that in itself is it’s kind of intriguing
because it means that and it’s actually fits in with lots of other things we found
out through Curiosity and through all these many missions that’s so funny saying we think about Uranus that you know we’ve had one thing there which flew past
pretty damn quickly there’s loads of stuff looking at Mars and one of the stories
A: we’re spoiled W: we are
one of stories which keeps coming back more and more is that this is a very
active dynamic place it’s got sort of well we know it has all seasonal
variations but it also has quite it’s got seismic activity it’s got possibly
sort of water very high salinity water which is sometimes flowing
A: there’s something going down the slopes for sure
W: yeah
A: I’m a huge fan of the dust devil videos
W: phenomenal
A: that I think Opportunity and Spirit had and they’re really pretty and that yes they’re incredibly tenuous
but they’re physical things that you can watch roll across the landscape and leave marks in the dust I mean it’s changing
W: in comparison to the Moon which I mean obviously simple
comparison but you know what something like that which is a very dead world with
very little happening I mean it’s got no atmosphere but it’s it’s just such you
know it doesn’t change much whereas this thing is a really lively different sort
of not ecosystem definitely but a different environment and climate so this just
fits into that pattern which is really cool I mean and there’s another interesting
riddle to try and solve we need more craft we need to go again
A: the last time I heard about methane on Mars they were saying it might be seasonal there’s a tentative M: yeah, so there is a seasonal variance
A: is it fitting in with that pattern
M: no this is a plume that sits outside of that pattern so there’s kind of a broad year the cycle of seasons but this is like a proper ‘plomp’
A: nothing like an outlier to mess with your day
M: something else has triggered it yeah I think you can distinguish between geological processes
that create methane and biological processes that produce methane by other
gases and details but Curiosity doesn’t have a full lab on board it doesn’t have
all the possible equipment you could ever want so with the instruments it’s got I don’t know if it can distinguish between them A: that’s a good question because the ExoMars rover that’s coming that’s going to be quite exciting does it have a methane
sniffer I’m imagining it probably would M: I imagine it’ll have something different
A: because it’s it’s going a little bit
further where Curiosity can’t quite just yet W: what about Insight has that monitoring as well?
A: I don’t know
W: I think it’s quite possible A: it’s got the equivalent of a cup
to the ground so I don’t know if it’s got time to sniff for methane at the
same time you never know
M: but even than this is a dynamic process are you gonna be able to with
either of those things find the thing because this is just a really
fascinating thing loads and loads of questions coming out of it and I guess these are questions we will come back around to in future episodes so I guess that’s a
good place to leave it thanks very much for listening
A: cheers all
W: bye [MUSIC]

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