Author Topic: Design a mission to Proxima b  (Read 68899 times)

Offline Oli

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Re: Design a mission to Proxima b
« Reply #60 on: 08/27/2016 11:55 pm »
Wouldn't the James Webb Space Telescope be able to get a picture of this planet? The star is just a red dwarf.

Not even close.  Proxima b has a separation from it's star of about 20 milli-arcseconds.  The band limited Lyot coronagraphs in JWST's instruments have inner working angles varying from 400 mas to 800 mas.  So the coronagraphs would not be able to spatially resolve the planet or even come close to it.

In addition to that, there is the contrast problem.  A terrestrial planet in the habitable zone of a mid M dwarf has a contrast of about 1 X 10^-8 dimmer than its host star.  The coronagraphs on JWST are designed for about 1 X 10^-5 contract, since they are simple coronagrpahs without any wavefront control or diffraction suppression.

WFIRST would get closer but the inner working angle of the coronagraph would still be too large for this planet.

The best bet to study it in detail in the next few years would be if the planet transits its host star, which would allow JWST to use Transmission or Emission Spectroscopy on it.

A guy on planetary.org said upcoming 30m+ telescopes should be able to directly image the planet.

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The planet is at the right place to have a temperature that allows the presence of liquid water on its surface. The question of habitability is however very complex. We need to confirm that this is a terrestrial planet. The best way to do that would be to directly image the planet using the giant telescopes equipped with extreme adaptive optics that are currently being built (i.e., the E-ELT, TMT, GMT). The angular separation between the star and the planet is 39 milli-arcsec, so a telescope as large as 30 m could resolve the system with the right instrument, detecting the planet and possibly giving us insights into its composition.

http://www.planetary.org/blogs/guest-blogs/2016/0824-proxima-centauri-b-have-we.html

Offline KelvinZero

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Re: Design a mission to Proxima b
« Reply #61 on: 08/28/2016 12:19 am »
A guy on planetary.org said upcoming 30m+ telescopes should be able to directly image the planet.
...
http://www.planetary.org/blogs/guest-blogs/2016/0824-proxima-centauri-b-have-we.html
Hey everyone, I have started up a thread on imaging btw.

Offline Bob Shaw

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Re: Design a mission to Proxima b
« Reply #62 on: 08/28/2016 12:24 am »
I read a paper that stated the solar focus is not sueful for sharp images.
no reason you cannot build bigger local imaging devices as you develop the infrastructor for making massive quantities of deuterium and antimatter

I'm sure I read somewhere that it was much further than that! The problem, of course, is not just going there but coming to rest.

Offline Bob Shaw

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Re: Design a mission to Proxima b
« Reply #63 on: 08/28/2016 12:30 am »
I'm hearing different comments re Proxima transits: are we in the right plane, or not?

If not, is the first step to send a high-ish speed probe to a point in space where it can loiter and look at transits?

Still difficult, but easier and easier as you head towards Proxima - perhaps a precursor mision...

Offline wdobner

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Re: Design a mission to Proxima b
« Reply #64 on: 08/28/2016 01:00 am »
How about Fission Fragment propulsion? 

http://www.osti.gov/scitech/servlets/purl/6868318/

This apparently old paper (attached below) about the early FFRE concept with fibers in fissionable material makes the case that a 10GW FFRE would deliver a 1 ton payload to Alpha Centauri in a century.  Now we just need to find a way to build a 10GW FFRE.  And find a way to radiate 10GW worth of energy from the spacecraft during its 40 years under thrust.

The paper does make the case that this version of an FFRE is well suited to radiating the heat away from the fibers directly.  Would that also apply to the dusty plasma FFRE that's been proposed more recently?

Offline Bob Shaw

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Re: Design a mission to Proxima b
« Reply #65 on: 08/28/2016 01:12 am »
How about Fission Fragment propulsion? 

http://www.osti.gov/scitech/servlets/purl/6868318/

This apparently old paper (attached below) about the early FFRE concept with fibers in fissionable material makes the case that a 10GW FFRE would deliver a 1 ton payload to Alpha Centauri in a century.  Now we just need to find a way to build a 10GW FFRE.  And find a way to radiate 10GW worth of energy from the spacecraft during its 40 years under thrust.

The paper does make the case that this version of an FFRE is well suited to radiating the heat away from the fibers directly.  Would that also apply to the dusty plasma FFRE that's been proposed more recently?

Fine for a Daedalus fast flyby, but we might want a fast (in interstellar terms) journey time and an encounter which is as slow as possible.

Offline Robotbeat

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Re: Design a mission to Proxima b
« Reply #66 on: 08/28/2016 02:14 am »
How about Fission Fragment propulsion? 

http://www.osti.gov/scitech/servlets/purl/6868318/

This apparently old paper (attached below) about the early FFRE concept with fibers in fissionable material makes the case that a 10GW FFRE would deliver a 1 ton payload to Alpha Centauri in a century.  Now we just need to find a way to build a 10GW FFRE.  And find a way to radiate 10GW worth of energy from the spacecraft during its 40 years under thrust.

The paper does make the case that this version of an FFRE is well suited to radiating the heat away from the fibers directly.  Would that also apply to the dusty plasma FFRE that's been proposed more recently?

Fine for a Daedalus fast flyby, but we might want a fast (in interstellar terms) journey time and an encounter which is as slow as possible.
Magsail to slow down. If this can be made to work (and I'm pretty sure it can, if any of these interstellar concepts can), then magsail will probably be used for every interstellar mission concept since it doesn't require any continuous power or propellant.
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Offline rdheld

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Re: Design a mission to Proxima b
« Reply #67 on: 08/28/2016 12:43 pm »
has there been any testing of a magsail?  certainly not in space.

Offline TakeOff

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Re: Design a mission to Proxima b
« Reply #68 on: 08/28/2016 01:35 pm »
A steady stream of launched lenses in a convoy where each lens refocuses the energy beam from the Solar System to the next mirror ahead. So that the probe can be continuously powered, and even enter stellar orbit by using a reflector ahead of it to decelerate. Earth providing the Proxima mission with all the energy it needs all the way. It would become a Silk Road through space, but unfortunately requires many years of daily launches of magical laser lenses at interstellar speeds.

The probe's payload materials would reconstruct (3D print) itself, using the latest engineering science on Earth, to different configurations. First just like a very thin javelin to avoid collisions while in transit. Then to a stellar wind sail to help entering orbit. Then to a surveying orbiter. Then to a lander. Then to a factory. And then to whatever we want it to do. (Such as an image of ourselves, since the only ones who could do it will have a Christian heritage).
I think a FOCAL telescope at 550 AU is the way to go.

https://en.wikipedia.org/wiki/FOCAL_(spacecraft)
Yeah, this has to be done before launching anything there anyway. The lensing begins only about 1% of the distance to Proxima. And it is doable in twenty-thirty years. Maybe FOCAL is the next $100 million initiative of Yuri Milner? It fits both with SETI and the Starshot. I'm glad he aims higher and bigger, but using the Sun as a gravitational lens would be my first priority if I had interstellar monies.
« Last Edit: 08/28/2016 01:48 pm by TakeOff »

Offline Robotbeat

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Re: Design a mission to Proxima b
« Reply #69 on: 08/28/2016 02:10 pm »
has there been any testing of a magsail?  certainly not in space.
It should be tested, I agree. But the idea relies on well-understood physics. A magnetic field resists the flow of charged particles (the interstellar plasma).
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Offline Paul451

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Re: Design a mission to Proxima b
« Reply #70 on: 08/29/2016 01:49 pm »
Re: Solar gravitational focus
The problem, of course, is not just going there but coming to rest.

The solar gravitational focus is not a focal point, but a focal line. There's no reason to stop. It starts working around 540-550AU, but becomes useful beyond 600AU. The butter-zone is around 1000AU.

« Last Edit: 08/29/2016 01:50 pm by Paul451 »

Offline rdheld

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Re: Design a mission to Proxima b
« Reply #71 on: 08/29/2016 10:55 pm »
People realize that any orbital telescope for the solar focus is orbiting the solar system barycenter and not the center of the Sun. How much fuel would be needed to keep it at a point at that focus?

Offline Robotbeat

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Re: Design a mission to Proxima b
« Reply #72 on: 08/30/2016 12:16 am »
People realize that any orbital telescope for the solar focus is orbiting the solar system barycenter and not the center of the Sun. How much fuel would be needed to keep it at a point at that focus?
Basically none compared to how much it took to get there. And because at that far out, the force from the Sun is small. At 550AU, the acceleration due to gravity is a microscopic 2*10^-8 m/s^2. A very small electric thruster is more than sufficient if you wanted to "hover" there (though it's not at all obvious you'd want to hover there versus coasting along the focal line).
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Offline MattMason

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Re: Design a mission to Proxima b
« Reply #73 on: 08/30/2016 12:39 am »
Some thoughts:

1) No nation or private group is ever going to commit to a "starship" or probe until more is known about its destination.
2) As someone said, a space probe won't work. Unless we can create true artificial intelligence for it to operate itself, it would be increasingly impossible to control, activate (you're not going to let it run its power and fuel out over years) or even receive the data it finds because the distance needed to send and receive signals aren't going faster than light (and let's leave the SF out of it until someone invents something truly FTL).

I agree with others. The great successes from exoplanet detection are in its comparatively infant stage. Bigger and better telescopes can and will get more info on Proxima-b and many other places before we commit to something.

And that also gives our autonomous technologies enough time to catch up. Don't need to launch a new AI-filled Voyager-type spacecraft and have it come back to kill us centuries later. ;)

Joke aside, having an exoplanet so comparably close is a comfort and scientific high-fiver for so many studies abd new technology, not to mention fodder for the tin-foil "the planet is doomed, let's evacuate" folks who worry that the whole solar system is hosed.
« Last Edit: 08/30/2016 12:40 am by MattMason »
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Offline Robotbeat

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Re: Design a mission to Proxima b
« Reply #74 on: 08/30/2016 02:06 am »
Some thoughts:

1) No nation or private group is ever going to commit to a "starship" or probe until more is known about its destination.
This statement is trivially true. There is serious scientific hay to be made by JWST and the 39m E-ELT, instruments already under construction, let alone ones that will be built in the future.
Quote
2) As someone said, a space probe won't work. Unless we can create true artificial intelligence for it to operate itself
Like what? think of a probe as just a sensor. It just needs to receive information and broadcast it.
Quote
it would be increasingly impossible to control,
You pre-program it with instructions, obviously.
Quote
activate (you're not going to let it run its power and fuel out over years)
And why not? Voyager 1 and 2 look like they'll probably last for half a century, which is longer than Breakthrough Starshot will need (for instance).
Quote
or even receive the data it finds because the distance needed to send and receive signals aren't going faster than light (and let's leave the SF out of it until someone invents something truly FTL).
Why does the probe need to receive commands? Just program it to send the right information. It doesn't need "AI" except in the trivial sense that is already used today on Mars.
« Last Edit: 08/30/2016 02:06 am by Robotbeat »
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Offline Paul451

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Re: Design a mission to Proxima b
« Reply #75 on: 08/30/2016 04:15 am »
Why does the probe need to receive commands? Just program it to send the right information. It doesn't need "AI" except in the trivial sense that is already used today on Mars.

Assuming a flyby, much can be pre-programmed. But over the length of the flight, we'll inevitably learn more about the dynamics of the target and other planets in the system, maybe Proxima's version of the asteroid and Kuiper Belt; maybe even a moon of the Prox b. Enough that we want to slightly tweak a) the flyby path, b) the observation priorities.

Not to mention changing the comms protocols to adapt to improved receivers. And maybe improving the programming of the probe itself, increasing its abilities, or working around bugs or hardware breakage that emerged during the long coast.

It's only a maximum of four and bit years away, by EM. Even a short 20-30 year flight time leaves enough time to want to tweak things. And the longer the coast, the more likely you want to make changes.

Assuming an orbiter mission... everything I just said, multiplied by every new discovery the probe makes.

No current or planned probe/lander/rover is capable of changing its own mission priorities based on new discoveries. For example, if the probe images Prox b and the image shows moons or rings (or both), no existing or planned system would be capable of autonomously understanding the discovery, let alone working out the orbital mechanics necessary to explore the new find(s).

Offline Paul451

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Re: Design a mission to Proxima b
« Reply #76 on: 08/30/2016 04:22 am »
People realize that any orbital telescope for the solar focus is orbiting the solar system barycenter and not the center of the Sun. How much fuel would be needed to keep it at a point at that focus?

It's worse than that. The telescope is, in essence, the "secondary mirror" of the whole system, the primary lens is the sun's gravity which can't be steered. So if you want to track a moving target (such as an orbiting planet), then - to skew the view - you need to physically move the telescope laterally to the direction of travel. Similarly to moving the suspended receiver on a fixed dish like Arecibo in order to track targets.

Offline Robotbeat

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Re: Design a mission to Proxima b
« Reply #77 on: 08/30/2016 01:08 pm »
People realize that any orbital telescope for the solar focus is orbiting the solar system barycenter and not the center of the Sun. How much fuel would be needed to keep it at a point at that focus?

It's worse than that. The telescope is, in essence, the "secondary mirror" of the whole system, the primary lens is the sun's gravity which can't be steered. So if you want to track a moving target (such as an orbiting planet), then - to skew the view - you need to physically move the telescope laterally to the direction of travel. Similarly to moving the suspended receiver on a fixed dish like Arecibo in order to track targets.
Depends on the field of view of the telescope.
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Offline TakeOff

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Re: Design a mission to Proxima b
« Reply #78 on: 08/30/2016 04:08 pm »
People realize that any orbital telescope for the solar focus is orbiting the solar system barycenter and not the center of the Sun. How much fuel would be needed to keep it at a point at that focus?

It's worse than that. The telescope is, in essence, the "secondary mirror" of the whole system, the primary lens is the sun's gravity which can't be steered. So if you want to track a moving target (such as an orbiting planet), then - to skew the view - you need to physically move the telescope laterally to the direction of travel. Similarly to moving the suspended receiver on a fixed dish like Arecibo in order to track targets.
Depends on the field of view of the telescope.
Yes, Proxima b's orbital diameter is only about 7 million kilometers. At about 40,000 million kilometer distance.

I wonder if Solar corona activity could not be monitored by close Solar probes to provide data to allow for adaptive gravitational lensing?

A FOCAL mission would have to be big like one of today's space telescopes, but I think that the Kuiper Belt and beyond is quickly getting much more interest today. Thanks to New Horizons and new distant Solar planetary discoveries. Along with heavier and cheaper launchers and miniaturization, it is getting more and more feasible to send a telescope to 600 AU (1% of a light year).

Offline MattMason

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Re: Design a mission to Proxima b
« Reply #79 on: 08/30/2016 05:31 pm »
Some thoughts:

1) No nation or private group is ever going to commit to a "starship" or probe until more is known about its destination.
This statement is trivially true. There is serious scientific hay to be made by JWST and the 39m E-ELT, instruments already under construction, let alone ones that will be built in the future.
Quote
2) As someone said, a space probe won't work. Unless we can create true artificial intelligence for it to operate itself
Like what? think of a probe as just a sensor. It just needs to receive information and broadcast it.
Quote
it would be increasingly impossible to control,
You pre-program it with instructions, obviously.
Quote
activate (you're not going to let it run its power and fuel out over years)
And why not? Voyager 1 and 2 look like they'll probably last for half a century, which is longer than Breakthrough Starshot will need (for instance).
Quote
or even receive the data it finds because the distance needed to send and receive signals aren't going faster than light (and let's leave the SF out of it until someone invents something truly FTL).
Why does the probe need to receive commands? Just program it to send the right information. It doesn't need "AI" except in the trivial sense that is already used today on Mars.

There's never been a probe that works autonomously. Probes can't anticipate the unexpected or fix issues themselves. From the Dawn probe, JAXA's Akatsuki to MER Spirit, human intervention is eventually required. Now multiply that matter when an issue is reported days, if not months later, and a command is sent to correct an issue when the probe might be pointed the wrong way or dead by the time the command gets there.

Durability of probes isn't my problem. JPL continually makes probes that outlast their mission design by years to decades. Now am I complaining about the versatility of many probes to fix many of its problems on its own. The problem is simply communication to fix what the probes cannot.

Voyager 1 and 2 have completed their missions.

Oh, we should also consider what power source these things would use. RTGs have a good life, but even they might have limits if a mission takes decades, and the scarcity of plutonium is one reason why Juno is using solar panels.

You're still talking years to send or receive anything. That can be managed except for some mission-critical issues that have occurred on missions before. Good planning and innovation might reduce those issues.
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