What would it take to directly image smaller exoplanets? A discussion... [REVIVED AND REDEFINED]

[UmbralRaptor]

I'm going to assume that the aforementioned Hubble images of Pluto are acceptable (ie: built up from a light curve). In that case, you want a space telescope with a starshade to get something earth-like (eg: HabEx, especially as the WFIRST proposals seem mostly dead.) The earliest plausible time is probably the 2030s, but delays are possible. We'll know more once the 2020 decadal survey is finished.

[Green Baron]

Timelapse and photo series of an exoplanet (Gas giant Beta Pictoris B) in a distance of 63ly. It orbits its sun in a distance comparable to Saturn and an orbit takes ~22 years. Images taken by the VLT.

https://www.eso.org/public/videos/

https://www.eso.org/public/images/potw/

Getting closer ;-)

(looks like the ESO site has momentary problems with its links)

Youtube works:

 

I am pretty confident that a larger interferometer with the participation of one of the huge dishes under construction can get a pretty close look on much smaller objects closer to their suns.

 

Edited November 14, 2018 by Green Baron

[Green Baron]

Just tried to log in as Green Barnard ....

It took 20 years of observation but there is a good chance that Barnards's Star has a cold rocky planet of >=3 earth masses and an orbit of around 233 days, derived from angular motion. Angular size of orbit could be 220 milliarcseconds, making it a candidate for future direct observation.

For comparison, structures that can be resolved with the EHT are in the range of 20 microarcseceonds ...

paper

 

Edited November 14, 2018 by Green Baron

[ThatGuyWithALongUsername]

2 minutes ago, Green Baron said:

Just tried to log in as Green Barnard ....

It took 20 years of observation but there is a good chance that Barnards's Star has a cold rocky planet of >=3 earth masses and an orbit of around 233 days, derived from angular motion. Angular size of orbit could be 220 milliarcseconds, making it a candidate for future direct observation.

For comparison, structures that can be resolved with the EHT are in the range of 20 microarcseceonds ...

paper

 

This is the first time I've been ninja'd.

6 hours ago, Green Baron said:

Timelapse and photo series of an exoplanet (Gas giant Beta Pictoris B) in a distance of 63ly. It orbits its sun in a distance comparable to Saturn and an orbit takes ~22 years. Images taken by the VLT.

https://www.eso.org/public/videos/

https://www.eso.org/public/images/potw/

Getting closer ;-)

(looks like the ESO site has momentary problems with its links)

Youtube works:

 

I am pretty confident that a larger interferometer with the participation of one of the huge dishes under construction can get a pretty close look on much smaller objects closer to their suns.

 

Yeah, other examples include 51 Pegasi B and a few others. The problem is, this currently only works on large planets orbiting far from their stars.

[Green Baron]

I wouldn't call it a "problem", there are already extraordinary results with the VLT and its new planet imager SPHERE.

https://www.eso.org/public/usa/news/eso1821/ (370ly away)

Just give it a few years more, i say. It is young technology, procedures, data evaluation, observation techniques, that is all in development. Soon(tm) we'll have an image of a rocky planet around a nearby star :-)

Edited November 14, 2018 by Green Baron

[ProtoJeb21]

I can’t believe just a few days ago we were talking about the hopes of imaging Super-Earths, and now there’s Barnard b, a nearly perfect candidate for direct imaging. It’s very nearby, orbits a very faint and small star, and has a pretty wide orbit. I used to think that we wouldn’t get a direct image of a Super-Earth until the 2030’s at the earliest, but if Barnard b does exist — and most evidence says yes — it could be imaged in the mid 2020’s by the new Extremely Large Telescope or the JWST. Unlike every other exoplanet in our solar neighborhood, Barnard b orbits far enough away that it probably hosts moons, which may be detectable by monitoring any changes in the disk of the planet (I’m assuming it’ll only be a dozen or so pixels across). Just the possibility of being able to directly see a rocky Super-Earth and potential detect exomoons at the same time is incredibly exciting. 

[ThatGuyWithALongUsername]

1 hour ago, Green Baron said:

I wouldn't call it a "problem", there are already extraordinary results with the VLT and its new planet imager SPHERE.

https://www.eso.org/public/usa/news/eso1821/ (370ly away)

Just give it a few years more, i say. It is young technology, procedures, data evaluation, observation techniques, that is all in development. Soon(tm) we'll have an image of a rocky planet around a nearby star :-)

I guess I misworded that- it's not a "problem" by any means, just a limitation. It would certainly be better to be able to image more, but being able to image just a few is still amazing and far, far better than nothing, if that made any sense.

58 minutes ago, ProtoJeb21 said:

I can’t believe just a few days ago we were talking about the hopes of imaging Super-Earths, and now there’s Barnard b, a nearly perfect candidate for direct imaging. It’s very nearby, orbits a very faint and small star, and has a pretty wide orbit. I used to think that we wouldn’t get a direct image of a Super-Earth until the 2030’s at the earliest, but if Barnard b does exist — and most evidence says yes — it could be imaged in the mid 2020’s by the new Extremely Large Telescope or the JWST. Unlike every other exoplanet in our solar neighborhood, Barnard b orbits far enough away that it probably hosts moons, which may be detectable by monitoring any changes in the disk of the planet (I’m assuming it’ll only be a dozen or so pixels across). Just the possibility of being able to directly see a rocky Super-Earth and potential detect exomoons at the same time is incredibly exciting. 

Exactly- very exciting!

[magnemoe]

2 hours ago, Green Baron said:

I wouldn't call it a "problem", there are already extraordinary results with the VLT and its new planet imager SPHERE.

https://www.eso.org/public/usa/news/eso1821/ (370ly away)

Just give it a few years more, i say. It is young technology, procedures, data evaluation, observation techniques, that is all in development. Soon(tm) we'll have an image of a rocky planet around a nearby star :-)

Yes, also this is mostly an budget issue. 
Find an couple of nice planets with oxygen and traces of methane in the Goldilocks zones and it get an higher priority.  

[Green Baron]

And observation time. These machines have a procedure for proposals and a consortium chooses which ones to carry through. There is a long list to work through and they are "booked" a long time in advance. So, even if they decide now to look at Barnard's face, it might take a year or so until they actually do.

But, who knows, maybe somebody is so nice and gives up his turn in favour of ....

(speculating :-))

Edited November 15, 2018 by Green Baron

[Green Baron]

Just checked the ESO site: the VLTI (I=interferometer) has a resolution power of a milliarcsecond at near infrared wavelengths (or as they say 0.1 AU at 100pc). So from that point it could do it if other circumstances permit and Barnard b does exist (which is not yet confirmed).

Edited November 15, 2018 by Green Baron

[Adstri]

I would love to see a close up of Proxima B in my lifetime. However, that seems like a bit of a stretch.

[Green Baron]

10 hours ago, Adstriduum said:

I would love to see a close up of Proxima B in my lifetime. However, that seems like a bit of a stretch.

Then there is a very good chance, unless your doctor recently had bad news for you

Edit: wait, what do you mean "close up" ? A portrait like earth from GEO (difficult) or just a few pixels across ?

Edited November 28, 2018 by Green Baron

[Ozymandias_the_Goat]

16 minutes ago, Green Baron said:

Then there is a very good chance, unless your doctor recently had bad news for you

Edit: wait, what do you mean "close up" ? A portrait like earth from GEO (difficult) or just a few pixels across ?

I’m assuming that a higher quality image is being suggested, as a planet a few pixels across seems very possible very soon. 

[ThatGuyWithALongUsername]

38 minutes ago, Ozymandias_the_Goat said:

I’m assuming that a higher quality image is being suggested, as a planet a few pixels across seems very possible very soon. 

Eh, just enough to picture just about any nearby planet in a few pixels would be ok. Thanks to SCIENCE, we could get surface maps from these anyway, kind of similar to hubble's observations of Pluto. We could also find major moons around these. As to larger resolutions, I am still intrigued by that aragoscope concept mentioned above- it sounds doable, eventually.

[Adstri]

8 hours ago, Green Baron said:

Then there is a very good chance, unless your doctor recently had bad news for you

Edit: wait, what do you mean "close up" ? A portrait like earth from GEO (difficult) or just a few pixels across ?

I think it's obvious 

[Green Baron]

Well.

i am a realistic guy, so little is obvious to me if it is not told openly :-).

You can approximate the angular resolution of a telescope under optimal conditions by the simple formula

R[radians] = wavelength/diameter.

The diameter (of the main mirror/front lens) can be exchanged with the baseline of an interferometer.

To convert radians to angles divide by (PI/180).

You know already that the the VLTI has a resolution of 0.1AU @ 100pc (1 milliarcsec).

Future music: imagine we manage to shoot a decent telescope with a ludicrous data transmitter speed to one of the earth/sun l4 or l5 (1 AU distance from earth) and combine it with GMT/TMT/E-ELT into an interferometer for the grown up. Pretty decent resolution, no ? 0.000000008m/150Gm is below 15 decimal digits. We would be in the range of 10⁻¹⁸ degrees.

I'd say, in 10-20 years this can be possible if economy permits.

Edited November 29, 2018 by Green Baron
milli. 0s do matter !

[ThatGuyWithALongUsername]

22 minutes ago, Green Baron said:

if economy permits.

There's the catch, isn't it...

[ThatGuyWithALongUsername]

As I said in the OP, I'm ignoring that orange banner thingy and reviving this thread. There's only like a page of old discussion to go through, right?

Anyway, I decided to clarify what I mean by direct imaging. Surface features would be amazing, but obviously we need to get to resolving even smaller planets as points, and then a few pixels, first. I was gonna make a new poll but the forums didn't like that.

New concept with mentioning here: the Terrascope!

 

(Mods, if this should have been a new thread, I'm sorry. I'll start a new thread if I have to.)

[Guest]

Upcoming high volume/ low cost launch systems might help with this! 

Imagine a fleet of 18m diameter telescopes >:)

Although I think the estimates to build even one of those^ was like 10 billion D:

[ThatGuyWithALongUsername]

3 hours ago, Dale Christopher said:

 

Imagine a fleet of 18m diameter telescopes >:)

Although I think the estimates to build even one of those^ was like 10 billion D:

Digging around on Wikipedia a bit shows that this concept has evolved into one of two possible designs being evaluated as LUVOIR (LUVOIR-B, specifically). Direct imaging of Earth-like exoplanets is mentioned as one of its capabilities. Apparently LUVOIR-B is only being evaluated as an 8 meter telescope, but the other design, LUVOIR-A, is 15 meters. LUVOIR-B would have to use a Starshade while LUVPIR-A can just use a Corona graph thingy like those used to detect larger exoplanets so far.

Really interesting and hopefully promising, but the cost is worrying, of course. Hopefully that $10 billion figure can be reduced with new technologies (and lower launch costs thanks to Starship or something like it) to make NASA more willing/able to fund it.

 

And, apparently, though I haven't seen any neat visualizations of it, LUVOIR-A can "just barely" fit in Starship dooded up also, although they could apparently optimize it a bit to make it fit better.

Edited August 6, 2019 by ThatGuyWithALongUsername