The Quest for Earth 2.0: Discovering Exoplanets by Suppressing Starlight
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- čas přidán 20. 07. 2024
- Seeing an Earth-like planet around a Sun-like star isn't possible with current telescopes. The difference in brightness is just too big. But future space telescopes will have multiple tricks up their sleeve specifically for that. Which ones? Finding out in this interview.
🟣 Guest: Dr Bertrand Mennesson
science.jpl.nasa.gov/people/m...
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00:00 Intro
01:16 Resolving Earth-size world around a Sun-like star
08:13 Coronagraphs and Adaptive optics
21:10 Other ideas
34:59 Nulling
39:00 Nancy Grace Roman
43:19 Unlimited budget telescope
49:58 Current obsessions
53:33 Final thoughts
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You are free to use my work for any purpose you like, just mention me as the source and link back to this video. - Věda a technologie
Loved this interview! He has a very good English, strong French accent, and is very smart. Perfect.
It must be painful for a Frog to have to speak English.
Another great interview. These can never be too long or too technical! Bertrand was brilliant.
Fraser dropping Knowledge Bombs! I certainly appreciate your insight and attention to detail 👍I become smarter through osmosis by watching your vids. Lol
NASA - Never a straight answer. Fascinating interview, Fraser!
Another great interview. Thank you both.
🤘😎🤘
Thanks for this video. I keep seeing comments and content that appears to assume we currently have the capability to detect earth-like planets around sun-like stars. Many of the 'Fermi Paradox' solutions that opine on the fantastic rarity of Earth just ignore the fact we have a sample of one on which to base our science
Great video Fraser. I hope you are having a great summer
Another great Interview.
Thanks Fraser.
Amazing! You see what happens when people unite
another great interview
This was marvelous in the depth with which you talked through the details.
My answer for what do you do if money is no object: all of the above in the biggest way possible… physically. Do an independent system with each one of these leading technologies. Specifically for the star shade concept, a few central telescopes in a Dyson-swarm-like cloud of mobile star shades, so repositioning doesn’t take nearly so long, and there’s redundancy against hardware failures and fuel limitations.
How important is the thea collision which created our moon to the Advent of life on earth? Is it possible that such an unlikely event could explain the great silence we find when looking for life on other worlds?
Would it be of use to send a coronagraph into geostationary orbit,
that a ground telescope could look at (around), and the satellite had a
“gentle nudge” mechanism?
Great great interview. Thanks
That and Breakthrough Starshot.
Breakthrough Starshot was envisioned to be on the ragged edge of what is physically conceivable without breaking the laws of physics as we know them. the technology and disposable energy scale is still many decades not centuries away.
@@zakeller I know what Breakthrough Starshot is and the only thing lacking is will.
We gotta get a solar sail going soon and do a Voyager flyby of Trappist or Proxima Centaury.
Change the "or" to an "and".
not feasble voyager wont truly leave the solar system for another 30,000 years
@@ShiriGoldberg He means a Voyager style flyby with a solar sail probe travelling a significant fraction of the speed of light. This is one of the more accepted strategies for an interstellar probe.
Wonderful interview!!!
Great interview - really informative. Thx
I love ya Fraser. Thank you for your work.
At the pace of technological advance it must be very frustrating to plan a project 10-15 yrs out.
Where's Prof Kipping when you need him?
A telescope with a 20 m primary mirror can be accommodated folded up in a tailormade starship.
I was excited to hear this video. I'm interested in habitable water / rocky exoplanets, so this was very inforamative.
what about using perspective, instead of 1 large star shade send 5, 10 etc smaller shades but space them out overlapping
This was really good
Or could our moon itself be used to suppress starlight with an orbiting observatory?
NASA was originally going to receive two optical telescope chassis when it was first announced in 2012. But they only received one, which was refurbished for Roman.
They haven't thought of how to use the second one yet. I like the idea of sending it to Mars.
@@frasercain It is a nice idea to send a larger telescope to orbit Mars, but it's not necessarily the most efficient method to map Mars in highest resolution. We can design pushbroom scanners to orbit much lower altitude than at Earth, since there's 1,000 the atmosphere. But I double-checked today with the Roman project; The second telescope is "gone" back to the dark side, and it ain't comin' back. Note all discussions what to do with the second scope ended around 2014.
Could there be advantages in positioning the Giant segmented screen and telescope in the moons shadow to remove solar heating effects?
Given that the Moon is tidally locked to the Earth, if we were to remove and relocate an entire layer of the Moon's crust, 200 miles deep, from the far side to the near side, dump truck load by dump truck load, how would this affect the Moon's center of mass and its distance from the Earth? Would this cause the Moon to move closer to the Earth, and what might be the implications for its orbit and rotational dynamics?
I just realized that the question show won't return until after summer break. 😢
The orbit won't change because you're not changing the mass of the Moon. You're just moving mass around on the moon. You have to throw mass off the Moon to push it just like satellites can't push themselves by moving their solar panels.
The spin won't change either, due to conservation of angular momentum. The Moon would remain tidally locked. If the trucks all took the same direction they might rotate the Moon like someone swinging their arms in a swivel chair, but it stops as soon as the trucks stop.
This would probably change the color of the Moon just because the fresh rocks won't be weathered by radiation and may be different material. It might also make the Moon look a little bigger from all the empty space you add by breaking up rocks to put in trucks.
Thanks for the answer. Would doing this effectively move the moon closer to the Earth?
@@FBravo2084 no, but I can see why intuition would lead you to that idea. The planets aren't fixed or attached to anything. Moving rocks from one side to another is a lot like trying to climb a ladder while falling. You can move to one end and back, but you can't climb your way to space no matter how fast you are. Planets just seem immovable because they're so huge. Moving the rocks is just trying to climb a planet size ladder floating in space. Same problem, just bigger.
So given that the diffraction limit is related to the wavelength in question, why not hunt in far UV?
Shorter wavelength. For the same diameter objective, more waves, therefore a finer diffraction limit.
Less blinding light. Stars of interest put out much less UV than visible or IR, but still enough to illuminate a planet. Less light of the appropriate wavelength to dazzle the sensor.
What am I missing?
The proportion is still the same, requiring 10^-10 suppression. Plus with less signal, SNR is less. Not to mention that surface scatter increases inversely with wavelength, as does the sensitivity to alignment stability and surface figure. i.e., lower wavelengths are inversely proportionally harder (to the power of each issue). HWO is being built to optimize observations (yes, at as low wavelengths as possible) given all systematic factors.
How do you keep an external star shade on the line-of-sight between the telescope and the star? Differential orbital motions and light pressure will tend to drag the star shade away from that line.
You really only get a couple of targets
@@frasercain You are correct; it does in fact require ~couple meters precision flying alignment, which is possible. As Fraser said, due to the time to get the star shade to that "alignment orbit" you have to do one target at a time. The L2 halo orbit actually lends itself nicely to repositioning. (So it is possible to get multiple targets, with enough time (and fuel)).
As a very amateur thought could their not be a retractable LCD screen on the telescope to activate pixels to block out the unwanted sun light and any background light?
It's not enough. Too much light gets around a physical barrier on the telescope
Does the technology exist to cast a large mirror on the Moon? Would the geographic North pole of the Moon be a good place to build a large observatory using such a mirror? A slow rotation can be used to create the proper curve while the mirror blank cools...
It would be destroyed by meteors. I love that idea though.
What about using existing structures as lenses? The sun, Jupyter or earth? By using the gravity or atmosphere to bend the light?
Fraser did an episode about this, search for "solar gravitational lens"
They are already entering the idea of something like this. It's called "Solar gravitational lens". It leverages gravitational lensing of our own sun.
@@BruceLee-mo5bi, I would love to see a prototype of an earth-based atmosphere lens first.
if its decided to use a two part telescope that needs refueling, put the telescope on the far side of moon and the other part as a satellite. We are apparently planing to back to the moon regularly. Would be relatively easy to refuel it as part of a trip there...maybe, also maybe easier to service scope compared to one at L point.
Why exactly does the shield need to be star shaped? Why not just a disk, or pacman shaped or something else?
Offsetting diffraction effects.
Because light behaves as a wave around the shade. It needs to cancel all the ripples from around the edges in addition to blocking the direct rays. Diffraction effects, as ReinReads said.
First view again?!? And. Comment and like how?
Good thoughts
who do we even search for exoplanets, when there is *zero* chance to ever visit them? shouldn‘t we concentrate instead on our solar system and try to find planet 9 instead?
this object, we could at least reach, with realistic engines
He’s right! He now has an obligation to the children to promptly show a positive bio signatures indicative of extraterrestrial life…😃👍🏾
I'd like to know if things would be easier if they had a magical camera that has something crazy like 40 bits per pixel (single channel gray scale) such that it has enough dynamic range to see the one part in 10 billion without needing to occlude the billion.
I know that such magical camera doesn't exist but I have reasons to believe that if you needed very few pixels (ideally 2 to 4) and it doesn't need to be fast, with some custom silicon it might be possible. So it wouldn't really be a camera but something built for this purpose.
Of course I don't know if there is enough angular resolution to separate the star and planet light in two pixels or if this makes any sense for this problem.
It's an interesting approach, though. The photons are there, you just need the dynamic range to get at them.
@@frasercain If indeed all that is needed is the dynamic range, it should be doable. Maybe even without custom silicon , it is on the edge of doable with discrete components.
A ccd/cmos sensor is just an array of tiny solar cells+tiny capacitors(part of the solar cell)+amplifiers+analog to digital converters.
If you forego the requirement for it all to be tiny and you need a few instead of millions, you can use a large capacitor and a high resolution ADC (to get 40 bits you would need to use a combination of opamps and multiple 32bit ADCs).
I am wondering, because I don't have the knowledge to know, if you could make a digital chronograph? Could a computer start by taking out the brightest light first and then work it's way down kinda thing? Or maybe by wave length. I'm thinking AI will probably be involved as well at some point in the post processing. Any work being done in this kind of area that you know about Fraser?
Unfortunately, no. In principle this works, but in practice we don't have a sensor that can do it. Digitally subtracting the light requires a sensor that is sensitive to brightness in billions of increments. Digital sensors can't do that (as far as I know). We can't find a planet glowing in the billionths if the sensor rounded to the nearest thousandth. The data just isn't there.
They do talk a bit about looking in the infrared for this reason. The Earth and Sun brightness aren't as different in some wavelengths.
Interesting - although it would be nice to know what kinds of things could be done to make the primary mirror ‘more chronograph friendly’ - he mentions that requirement several times, but does not give us any hints about how it might be achieved.
What if you combine the starshade system with solar sails to save fuel allow for more pointings
Why is skirting around how the corrections are physically actuated? Around 17:00
Do planets cast a shadow in their starlight and could we identify planets using the shadow cast by a planet with a chronograph device for those face on orbital solar systems?
Cool question! Look up 'zodiacal light'. If there's a shadow it would be in there, but it won't be much and would only be a short cone because stars are so much bigger than planets. The Moon wouldn't fit in Earth's shadow if it were much farther away. The shadow would also be much harder to see than the planet. I'm not sure we've even observed such shadows in our own system.
My question is about the LIFE concept.
Doesn't this "cancelling out light" only work with coherent light. (LASER) And as starlight is not a Laserlight that would be achieved by the adaptive optics technology?
How is it possible that only the starlight is cancelled out, shouldn't the planet also be gone?
For the sunshade concept: Why don't they just put such thing in an orbit around L2 to create occultations on random stars for JWST?
People have proposed putting starshades into orbits like that and using them with Earth-based observatories.
I don't know the full details, but nulling works with any light as long as you're looking at the same object from two different perspectives so you line up to the specific wavefronts, like interferometry.
The star emits light at one set of frequencies, while planets reflect it back at other frequencies. Essentially, the goal is to block the light coming from the sun in order to see the planet behind.
Like the moon blocking the sun during the solar eclipse and revealing the corona.
Serge moves into science
Its actually a lot easier. Juust created a simulation. Themepark galaxy and neuralink in to the new universe meta
The various cameras on and around Mars that can see the Earth, can we see the continents during its rotation so that one frame shows the light centered on India and the next shows more of the western Pacific and less of the Mediterranean. There should be more resolution with each pass as each frame is different.
Take some pictures of a globe from the other side of the dark room to test. Look for a cartouche in the Pacific Ocean. LoL
Flip book astronomy using rapidly rotating blocking exposures across x and y axis...then compiling the results...creating a flip book so to speak..
Very interesting, even if you find a habitable world or life, then your seeing it how it was millions of years ago, depending on far away it is. The planet and life (now), could be uninhabitable, or no more life at all. Wish we could study these things in real time.
It's a few hundred years, maximum, not millions. We can't see that far.
let's say we discovered this planet. so what, how would we contact any inhabitants? how would we ever hope to get there. what if these inhabitants have already discovered earth?
what an enormous waste of time, energy and potentially money. we have more than enough pressing needs right here, let's work on them first,
Joupitère analogue ouais
Does he actually answer any questions?
Earth 1.5 would do me...
i think it will be a difficult task to be able to view the earth-like planet. has NASA thought of sending maybe one or couple of scientists to maybe do the exploration? i understand it would be a risk and probably a one way travel. maybe we just need a reliable but small shuttle to carry 1 or a few astronauts. and some extra fuel or booster rockets to reach a destination.
For all the PhD's given out and intelligent people working in professional astronomy for decades and decades, it beggars belief that these astronomers are only now, in 2024, proposing to build the most important and potentially life/perception-altering telescope to identify Earth-like exoplanets orbiting around Sun-like distant stars, where such "Goldilocks planets" could host lifeforms perhaps equal (but different) to those on Earth. What took them so long to propose it? That's crazy!
The technology is so advanced and required new discoveries. Right now it's only "maybe" possible.
We can only prove we are not alone.
Great interview, thanks! Just to answer your question, yes we are alone. Never bet against Fermi, you'll lose every time.
It isn’t clear that any of the effects we’re observing are actually from planets.
Maybe it's selfish and entitled, but I wish you made shortened edited version/summaries of these interviews. Feels like there is a lot of interesting stuff in them but this format isn't my cup of tea at least.
Can't understand half of what your guest is saying.