Author Topic: Design a mission to Proxima b  (Read 16484 times)

Offline whitelancer64

Re: Design a mission to Proxima b
« Reply #20 on: 08/25/2016 05:31 PM »
Wouldn't the James Webb Space Telescope be able to get a picture of this planet? The star is just a red dwarf.
Maybe. It depends on the apparent distance to the star. JWST does have coronagraphs that might enable a direct image to be taken of Proxima b, but if it can only distinguish Proxima b when it's at the furthest from the star from our perspective, it might be tricky to get the timing right.
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Online RonM

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Re: Design a mission to Proxima b
« Reply #21 on: 08/25/2016 05:42 PM »
Wouldn't the James Webb Space Telescope be able to get a picture of this planet? The star is just a red dwarf.
Maybe. It depends on the apparent distance to the star. JWST does have coronagraphs that might enable a direct image to be taken of Proxima b, but if it can only distinguish Proxima b when it's at the furthest from the star from our perspective, it might be tricky to get the timing right.

With an 11.2 day orbit, a well planned observation campaign should be able to catch Proxima b, assuming JWST can image it.

Offline TheSpaceRod

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Re: Design a mission to Proxima b
« Reply #22 on: 08/25/2016 05:47 PM »
Antimatter should do the trick for interstellar propulsion. You'd still need to invent some technologies, i.e. relatively affordable production and reliable storage of sufficient amounts of antimatter.

Offline whitelancer64

Re: Design a mission to Proxima b
« Reply #23 on: 08/25/2016 05:48 PM »
Wouldn't the James Webb Space Telescope be able to get a picture of this planet? The star is just a red dwarf.
Maybe. It depends on the apparent distance to the star. JWST does have coronagraphs that might enable a direct image to be taken of Proxima b, but if it can only distinguish Proxima b when it's at the furthest from the star from our perspective, it might be tricky to get the timing right.

With an 11.2 day orbit, a well planned observation campaign should be able to catch Proxima b, assuming JWST can image it.
We do have a couple of years to nail down the orbital inclination, distance, and time more precisely, and I'm certain that Proxima Centauri will be getting some intense scrutiny by many people!
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
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Online sevenperforce

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Re: Design a mission to Proxima b
« Reply #24 on: 08/25/2016 07:11 PM »
Let's see here. Inclination will be an issue, which means we would definitely, absolutely have to execute a solar slingshot in order to get a free inclination change. The easiest way to do a solar slingshot, of course, is to do a Jovian slingshot. In order to actually get a gravity assist from Jupiter, you'd need to set it all up with a Martian slingshot.

So we have the beginnings of a mission profile. Let's limit ourselves to three LEO BFR launches and just two on-orbit robotic assembly events. Generously, let's say this gives us 900 tonnes in LEO.

From a mass basis, is it cheaper to use SEP or a solar sail to do the burn for the martian slingshot, or should chemical propulsion be used?

Once the slingshots begin, maximum propulsive capacity should be saved for the periapse of the solar slingshot for Oberth reasons. Chemical propulsion is nice here because it can permit very high thrust, which is ideal for an oberth maneuver, but would an ablative solar sail be a better use of mass? Or would it be better to have a combination of chemical propulsion at periapse followed by the deployment of a solar sail?

Remember that your whole system needs to be broken up into 300-tonne blocs in order to fit on three BFR launches.

Offline redliox

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Re: Design a mission to Proxima b
« Reply #25 on: 08/25/2016 07:49 PM »
Maybe. It depends on the apparent distance to the star. JWST does have coronagraphs that might enable a direct image to be taken of Proxima b, but if it can only distinguish Proxima b when it's at the furthest from the star from our perspective, it might be tricky to get the timing right.

With an 11.2 day orbit, a well planned observation campaign should be able to catch Proxima b, assuming JWST can image it.
We do have a couple of years to nail down the orbital inclination, distance, and time more precisely, and I'm certain that Proxima Centauri will be getting some intense scrutiny by many people!

Now that's it's confirmed to exist, I'm sure a floodgate will open to both it and Alpha Centauri.

I had read on (I believe it was Space.com) that Hubble was just below the threshold of detecting/imaging Proxima b, but the JWST should be able to; not certain on WFIRST but its coronagraph would greatly help.  The HD space telescope hopefully will be built with imaging Proxima's planets as a priority now.

Aside from pinning down the properties on the new planet, another objective should be to confirm is there's more to Proxima's system.  There's suspicions of a 2nd, outer planet, but no confirmation just yet.  If b can't be directly imaged even with new space telescopes, its would-be outer neighbors could be resolved.

As for a mission flying directly to Proxima...hard to say what should or could be done.  The starshot idea Steven Hawkins announced is probably the best we can do momentarily, and while I'm not a fan of solar sails I will say there's merit in employing them for star travel as opposed to heavy reactor-powered systems.  Depending on mass constraints, there could be 2 sails deployed; the 1st would using laser power from Earth but the 2nd would be deployed near Proxima to brake using the star's light; I suggest 2 because the 1st sail would probably be heavily damaged over time by the time the probe arrives.  Most likely the mission would be a flyby of Proxima but it could divert to visit Alpha Centauri next.

I'd say keep a Proxima probe in mind, but on the back burner, and primarily invest in a large space telescope charged with directly imaging anything around Proxima and AC.  Establishing the basic size, composition, and atmosphere ought to be possible in the near future; if you wish to be (reasonably) ambitious size the 'scope to be able to see continents on Proxima planets.
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Offline Star One

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Design a mission to Proxima b
« Reply #26 on: 08/25/2016 08:19 PM »
For those interested JWST appears to be discussing Proxima b on its Twitter feed at the moment.
« Last Edit: 08/25/2016 08:19 PM by Star One »

Offline Robotbeat

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Re: Design a mission to Proxima b
« Reply #27 on: 08/25/2016 08:49 PM »
Let's see here. Inclination will be an issue, which means we would definitely, absolutely have to execute a solar slingshot in order to get a free inclination change. The easiest way to do a solar slingshot, of course, is to do a Jovian slingshot. In order to actually get a gravity assist from Jupiter, you'd need to set it all up with a Martian slingshot.

So we have the beginnings of a mission profile. Let's limit ourselves to three LEO BFR launches and just two on-orbit robotic assembly events. Generously, let's say this gives us 900 tonnes in LEO.

From a mass basis, is it cheaper to use SEP or a solar sail to do the burn for the martian slingshot, or should chemical propulsion be used?

Once the slingshots begin, maximum propulsive capacity should be saved for the periapse of the solar slingshot for Oberth reasons. Chemical propulsion is nice here because it can permit very high thrust, which is ideal for an oberth maneuver, but would an ablative solar sail be a better use of mass? Or would it be better to have a combination of chemical propulsion at periapse followed by the deployment of a solar sail?

Remember that your whole system needs to be broken up into 300-tonne blocs in order to fit on three BFR launches.

...none of this is relevant for an interstellar mission lasting less than a century. Inclination not an issue AT ALL. Are you referring to a gravitational focus mission?
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Online sevenperforce

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Re: Design a mission to Proxima b
« Reply #28 on: 08/25/2016 10:14 PM »
Let's see here. Inclination will be an issue, which means we would definitely, absolutely have to execute a solar slingshot in order to get a free inclination change. The easiest way to do a solar slingshot, of course, is to do a Jovian slingshot. In order to actually get a gravity assist from Jupiter, you'd need to set it all up with a Martian slingshot.

So we have the beginnings of a mission profile. Let's limit ourselves to three LEO BFR launches and just two on-orbit robotic assembly events. Generously, let's say this gives us 900 tonnes in LEO.


...none of this is relevant for an interstellar mission lasting less than a century. Inclination not an issue AT ALL. Are you referring to a gravitational focus mission?
I was more saying...given current and near future tech, what's the greatest dV you could get out of three BFR launches for an interstellar flyby mission?

If inclination is not an issue that still probably makes no difference since an oberth around the sun is going to be huge regardless.

Offline MAC74

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Re: Design a mission to Proxima b
« Reply #29 on: 08/25/2016 10:44 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.

Offline Robotbeat

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Re: Design a mission to Proxima b
« Reply #30 on: 08/25/2016 10:56 PM »
Let's see here. Inclination will be an issue, which means we would definitely, absolutely have to execute a solar slingshot in order to get a free inclination change. The easiest way to do a solar slingshot, of course, is to do a Jovian slingshot. In order to actually get a gravity assist from Jupiter, you'd need to set it all up with a Martian slingshot.

So we have the beginnings of a mission profile. Let's limit ourselves to three LEO BFR launches and just two on-orbit robotic assembly events. Generously, let's say this gives us 900 tonnes in LEO.


...none of this is relevant for an interstellar mission lasting less than a century. Inclination not an issue AT ALL. Are you referring to a gravitational focus mission?
I was more saying...given current and near future tech, what's the greatest dV you could get out of three BFR launches for an interstellar flyby mission?

If inclination is not an issue that still probably makes no difference since an oberth around the sun is going to be huge regardless.
Right. But "huge" relative to our current speeds. But even the Oberth boost is basically useless compared to the delta-v needed for less-than-a-century interstellar travel. You're limited by the escape velocity of the Sun. It'd be better if we had a black hole or at least a white dwarf or neutron star...
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Offline KelvinZero

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Re: Design a mission to Proxima b
« Reply #31 on: 08/25/2016 11:13 PM »
In another thread someone suggested using a lightsail to hide the star. That was an interesting idea. Could that help even if it were not even a thousandth of the distance there? That is still a long way. Im not sure how you would keep the lightsail between your telescope and star for any prolonged period of time. Perhaps both need to have escaped the solarsystem.

Offline Star One

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Re: Design a mission to Proxima b
« Reply #32 on: 08/25/2016 11:39 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.
Well what's been posted on Twitter tonight by the official JWST account would seem to disagree with you on completely precluding anything at this point in time.

https://mobile.twitter.com/NASAWebb/status/768923069805125632
« Last Edit: 08/25/2016 11:42 PM by Star One »

Offline AS_501

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Re: Design a mission to Proxima b
« Reply #33 on: 08/25/2016 11:54 PM »
BFR launches probe that is just large enough to transmit some data and images from Prox b.  Stack 4, 5, or more high-energy upper stages on top of the BFR.  I wonder how fast the probe would be moving when the final stage drops away?  This would be Atlas V 551/New Horizons on steroids+.  Alas, I suspect even this scheme would not be enough to reach an appreciable fraction of light speed.

Offline Robotbeat

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Re: Design a mission to Proxima b
« Reply #34 on: 08/26/2016 01:36 AM »
BFR launches probe that is just large enough to transmit some data and images from Prox b.  Stack 4, 5, or more high-energy upper stages on top of the BFR.  I wonder how fast the probe would be moving when the final stage drops away?  This would be Atlas V 551/New Horizons on steroids+.  Alas, I suspect even this scheme would not be enough to reach an appreciable fraction of light speed.
No. Chemical propulsion is utterly incapable of interstellar travel within any kind of reasonable timeframe. And it doesn't even matter how big your rocket is. Could be the mass of the Sun, but still wouldn't have enough fuel to reach even 5% of lightspeed.
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Offline Zed_Noir

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Re: Design a mission to Proxima b
« Reply #35 on: 08/26/2016 02:16 AM »
BFR launches probe that is just large enough to transmit some data and images from Prox b.  Stack 4, 5, or more high-energy upper stages on top of the BFR.  I wonder how fast the probe would be moving when the final stage drops away?  This would be Atlas V 551/New Horizons on steroids+.  Alas, I suspect even this scheme would not be enough to reach an appreciable fraction of light speed.

Better yet. Parked a stripped down empty BFR core with one Raptor Vac engine at Lagrange point 2. Added combo NEP & SEP cruise module and Proxima probe. Top off and lit the BFR core for the initial boost. Switch to ion thrusters powered by solar arrays & RTGs after separating from depleted BFR core. Jettisoning the solar arrays after going beyond Jupiter orbital distance. Then continuous boost with ion thruster powered by RTGs until Xenon depletion. Finally the probe separated from cruise module and is on ballistic encounter with the Proxima system. Of course presuming the probe lasted long enough for the encounter observation and got a working radio transmitter for a brief data transmission. For a reasonable chance of mission success, a series of probe launches is needed.


Offline Robotbeat

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Re: Design a mission to Proxima b
« Reply #36 on: 08/26/2016 02:29 AM »
BFR launches probe that is just large enough to transmit some data and images from Prox b.  Stack 4, 5, or more high-energy upper stages on top of the BFR.  I wonder how fast the probe would be moving when the final stage drops away?  This would be Atlas V 551/New Horizons on steroids+.  Alas, I suspect even this scheme would not be enough to reach an appreciable fraction of light speed.

Better yet. Parked a stripped down empty BFR core with one Raptor Vac engine at Lagrange point 2. Added combo NEP & SEP cruise module and Proxima probe. Top off and lit the BFR core for the initial boost. Switch to ion thrusters powered by solar arrays & RTGs after separating from depleted BFR core. Jettisoning the solar arrays after going beyond Jupiter orbital distance. Then continuous boost with ion thruster powered by RTGs until Xenon depletion. Finally the probe separated from cruise module and is on ballistic encounter with the Proxima system. Of course presuming the probe lasted long enough for the encounter observation and got a working radio transmitter for a brief data transmission. For a reasonable chance of mission success, a series of probe launches is needed.
No, this is still not nearly good enough. It'll be hundreds (if not thousands) of years before your probe arrives.

The usual approaches to exploring our solar system simply do not work.

Do the math!
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Offline Zed_Noir

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Re: Design a mission to Proxima b
« Reply #37 on: 08/26/2016 03:53 AM »

Better yet. Parked a stripped down empty BFR core with one Raptor Vac engine at Lagrange point 2. Added combo NEP & SEP cruise module and Proxima probe. Top off and lit the BFR core for the initial boost. Switch to ion thrusters powered by solar arrays & RTGs after separating from depleted BFR core. Jettisoning the solar arrays after going beyond Jupiter orbital distance. Then continuous boost with ion thruster powered by RTGs until Xenon depletion. Finally the probe separated from cruise module and is on ballistic encounter with the Proxima system. Of course presuming the probe lasted long enough for the encounter observation and got a working radio transmitter for a brief data transmission. For a reasonable chance of mission success, a series of probe launches is needed.
No, this is still not nearly good enough. It'll be hundreds (if not thousands) of years before your probe arrives.

The usual approaches to exploring our solar system simply do not work.

Do the math!

Of course it will take many decades of flight time. It is what is possible with near term technology.

:P Please offer an alternate scheme that you think will be faster that might be possible in the next few decades..


Offline Elmar Moelzer

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Re: Design a mission to Proxima b
« Reply #38 on: 08/26/2016 04:00 AM »
At yesterdays NIAC presentation Philip Lubin from the University of California, Santa Barbara presented their concept for Directed Energy propulsion to accelerate a wafer sized spacecraft to 0.2c.
That would make Proxima B a 25 year mission.
http://livestream.com/viewnow/NIAC2016/videos/133838016

Offline MATTBLAK

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Re: Design a mission to Proxima b
« Reply #39 on: 08/26/2016 07:56 AM »
(My Concept For):

Interstellar Precursor Probe (IPP): Year of approximately 2030-2040 - Deep Kuiper Belt exploration spacecraft to develop technologies for eventual use on a future late-21st or early 22nd century interstellar probe for a mission to Proxima Centauri and it’s observed planetary target(s). The IPP concept would be the most expensive and sophisticated deep space exploration probe concept ever attempted.

Launch vehicle(s):  1x SLS Block 2 or 2B, utilizing advanced upper stage and boosters, plus 1x Falcon 9 (advanced) or a Vulcan 6-Solid Rocket Motor launcher. OR: 1x Falcon 9 (advanced version, with a Raptor powered upper stage) plus 2x Falcon Heavies – rendezvous and dock 1x 25 ton spacecraft plus 2x 60 ton Earth Departure Stages to assemble the ‘Mission Stack’.

Spacecraft: Tough, heavily-shielded ‘lightweight’ probe that nonetheless masses approximately 25 metric tons including Xenon propellants, instruments, cameras, ejectable solar power arrays, a large unfolding high-gain antenna and a mixed set of Plutonium and AM 241 Radiosotopic Thermo-Electric generators. The Plutonium RTGs are predominantly for the spacecraft’s hybrid Ion propulsion system – most likely an advanced and evolved array of gridded Hall thrusters. The very long life Americium 241 RTGs are for the science instruments and cameras. The SLS launcher uses a 10 meter option payload fairing to maximise options for a large, deployable high gain antenna array that will deploy out to between 15-to-18 meters in diameter.
SLS Mission profile: IPP is launched into Earth parking orbit on Vulcan or Falcon 9 launcher. SLS Block 2 series launcher with Exploration Upper Stage only as payload (largest possible propellant load) sends the EUS into an orbit within reach of the IPP, which then rendezvous and docks with the EUS.
The Earth Departure burn is then followed by some sort of staged combination of Earth, Venus and Jupiter gravitational assist flybys to eventually send the IPP on a high-speed departure of the Solar System. Within the inner solar system, the solar arrays feed power to the electric drive system, complimenting the Plutonium RTG sets. Though somewhat before the arrival in Jupiter’s space, the arrays are ejected and the Plutonium RTGs take up the lone task of supplying power to the electric drive thrusters, constantly 'burning' their tons of Xenon gas. Although the power level for the electric drive is now reduced; the IPP would then be already moving at very high speed (how fast??)
The electric drive would keep operating until the xenon propellant is starting to dwindle, by which time a flyby or two of large Kuiper belt objects should have occurred.

As for an Interstellar probe? Nobody can see the future with much other than mere practicality at the moment. But we can truthfully say that an Interstellar explorer should dwarf the IPP in size and complexity, the way relatively crudely-equipped polar explorers of the past are outstripped today by icebreakers, GPS, support ships and various aircraft.

http://www.kiss.caltech.edu/study/science/KISS%20How%20Fast%20How%20Far_strange_final.pdf

https://icubesat.files.wordpress.com/2015/05/icubesat-2015_org-b-3-4_amrtg_ambrosi.pdf

http://www.lpi.usra.edu/meetings/nets2012/pdf/3043.pdf


« Last Edit: 08/26/2016 04:43 PM by MATTBLAK »
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