Author Topic: Would a flyby probe to the chromosphere be possible?  (Read 809 times)

Offline TakeOff

  • Full Member
  • ***
  • Posts: 353
  • Liked: 73
  • Likes Given: 93

The transition zone between the chromosphere and the corona is "only" 6000 degrees hot and seems to be key to understanding the corona. Could a probe fly through it and generate valuable science data?


It could be enclosed in a spherical ablative shield filled with cryogenic material. When it is gasified, maybe it could be ejected to get rid of heat and provide propulsion to shorten the high temperature exposure time. There's quite an Oberth effect.


What science could be done without exposing any sensors? I suppose that the temperature and magnetic field can be measured. And if it can be well located, maybe by an orbiting spacecraft, its movements might reveal the density of the plasma.
« Last Edit: 10/03/2017 10:16 PM by TakeOff »

Offline Martin.cz

  • Member
  • Member
  • Posts: 78
  • Liked: 7
  • Likes Given: 121
Re: Would a flyby probe to the chromosphere be possible?
« Reply #1 on: 10/03/2017 10:30 PM »
Not really basing this on any concrete computations but I think any such maneuvers would take too long (hours/days) for the kind of trajectories we can realistically send the probe on with current technology. So all of the ablator would likely be gone long before the closest approach concludes.

But I might as well be just forgetting something and one of our trajectory gurus might fix me. :)

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 31222
  • Cape Canaveral Spaceport
  • Liked: 9494
  • Likes Given: 298
Re: Would a flyby probe to the chromosphere be possible?
« Reply #2 on: 10/04/2017 01:31 AM »

It could be enclosed in a spherical ablative shield filled with cryogenic material. When it is gasified, maybe it could be ejected to get rid of heat and provide propulsion to shorten the high temperature exposure time. There's quite an Oberth effect.


What science could be done without exposing any sensors? I suppose that the temperature and magnetic field can be measured. And if it can be well located, maybe by an orbiting spacecraft, its movements might reveal the density of the plasma.


How is the cryogen going to be stored for the years it is going to take to get there?

How is temp is going to be measured if no exposed sensors.  how is magnetic field going to be measured in an enclosed case?


Online Blackstar

  • Veteran
  • Senior Member
  • *****
  • Posts: 10826
  • Liked: 2338
  • Likes Given: 1
Re: Would a flyby probe to the chromosphere be possible?
« Reply #3 on: 10/04/2017 01:37 AM »

The transition zone between the chromosphere and the corona is "only" 6000 degrees hot and seems to be key to understanding the corona. Could a probe fly through it and generate valuable science data?


It could be enclosed in a spherical ablative shield filled with cryogenic material. When it is gasified, maybe it could be ejected to get rid of heat and provide propulsion to shorten the high temperature exposure time. There's quite an Oberth effect.


What science could be done without exposing any sensors? I suppose that the temperature and magnetic field can be measured. And if it can be well located, maybe by an orbiting spacecraft, its movements might reveal the density of the plasma.


What is the science question you want to answer?

I suggest getting a copy of the heliophysics decadal survey and looking in there.

Offline TakeOff

  • Full Member
  • ***
  • Posts: 353
  • Liked: 73
  • Likes Given: 93
Re: Would a flyby probe to the chromosphere be possible?
« Reply #4 on: 10/04/2017 09:21 AM »
Not really basing this on any concrete computations but I think any such maneuvers would take too long (hours/days) for the kind of trajectories we can realistically send the probe on with current technology. So all of the ablator would likely be gone long before the closest approach concludes.

But I might as well be just forgetting something and one of our trajectory gurus might fix me. :)
The Parker Solar Probe, at 10 Solar radii from the Sun as closest, will achieve a speed of 200 km/s pass the Sun. It then takes it two hours to pass one diameter of the Sun's disk. A flyby probe ten times closer, well, I better ask someone else here to estimate what its highest speed would be. And what the Oberth bonus then would be if heat exhaust can be used for propulsion.

I suppose that a Krafft-Ericke type trajectory to Jupiter is the best option for a one time Solar flyby. PSP uses Venus to gradually narrow its orbit, while a flyby would want to get it over with asap.

Offline TakeOff

  • Full Member
  • ***
  • Posts: 353
  • Liked: 73
  • Likes Given: 93
Re: Would a flyby probe to the chromosphere be possible?
« Reply #5 on: 10/04/2017 09:27 AM »

It could be enclosed in a spherical ablative shield filled with cryogenic material. When it is gasified, maybe it could be ejected to get rid of heat and provide propulsion to shorten the high temperature exposure time. There's quite an Oberth effect.


What science could be done without exposing any sensors? I suppose that the temperature and magnetic field can be measured. And if it can be well located, maybe by an orbiting spacecraft, its movements might reveal the density of the plasma.

How is the cryogen going to be stored for the years it is going to take to get there?

How is temp is going to be measured if no exposed sensors.  how is magnetic field going to be measured in an enclosed case?
Can't a spacecraft be cryocooled in space for half a dozen years? Aren't several telescopes?

If there are radial sensors in the shield, it should be possible to estimate the temperature from the rate of ablation and the heating of the interior of the spacecraft. The enclosing need not be a Faraday's cage. Carbon materials and ceramics seem popular for heat shields.

I wonder if it is physically possible, or if everything is zapped into plasma if it dives through and under the corona.
« Last Edit: 10/04/2017 09:28 AM by TakeOff »

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 31222
  • Cape Canaveral Spaceport
  • Liked: 9494
  • Likes Given: 298
Re: Would a flyby probe to the chromosphere be possible?
« Reply #6 on: 10/04/2017 12:38 PM »
Not really basing this on any concrete computations but I think any such maneuvers would take too long (hours/days) for the kind of trajectories we can realistically send the probe on with current technology. So all of the ablator would likely be gone long before the closest approach concludes.

But I might as well be just forgetting something and one of our trajectory gurus might fix me. :)
The Parker Solar Probe, at 10 Solar radii from the Sun as closest, will achieve a speed of 200 km/s pass the Sun. It then takes it two hours to pass one diameter of the Sun's disk. A flyby probe ten times closer, well, I better ask someone else here to estimate what its highest speed would be. And what the Oberth bonus then would be if heat exhaust can be used for propulsion.

I suppose that a Krafft-Ericke type trajectory to Jupiter is the best option for a one time Solar flyby. PSP uses Venus to gradually narrow its orbit, while a flyby would want to get it over with asap.

Heat exhaust is not available for propulsion. Flyby is not feasible, Delta v is too great

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 31222
  • Cape Canaveral Spaceport
  • Liked: 9494
  • Likes Given: 298
Re: Would a flyby probe to the chromosphere be possible?
« Reply #7 on: 10/04/2017 12:42 PM »

It could be enclosed in a spherical ablative shield filled with cryogenic material. When it is gasified, maybe it could be ejected to get rid of heat and provide propulsion to shorten the high temperature exposure time. There's quite an Oberth effect.


What science could be done without exposing any sensors? I suppose that the temperature and magnetic field can be measured. And if it can be well located, maybe by an orbiting spacecraft, its movements might reveal the density of the plasma.

How is the cryogen going to be stored for the years it is going to take to get there?

How is temp is going to be measured if no exposed sensors.  how is magnetic field going to be measured in an enclosed case?
Can't a spacecraft be cryocooled in space for half a dozen years? Aren't several telescopes?

If there are radial sensors in the shield, it should be possible to estimate the temperature from the rate of ablation and the heating of the interior of the spacecraft. The enclosing need not be a Faraday's cage. Carbon materials and ceramics seem popular for heat shields.

I wonder if it is physically possible, or if everything is zapped into plasma if it dives through and under the corona.

Not a whole spacecraft.   Radial sensors are not going to know what it happening outside the spacecraft.  What is happening to the surface is not the same as the environment.  There still will be metals involved in the shell construction.

Offline Don2

  • Member
  • Posts: 80
  • Liked: 16
  • Likes Given: 0
Re: Would a flyby probe to the chromosphere be possible?
« Reply #8 on: 10/08/2017 08:08 AM »
Tungsten or carbon can go up to about 4000K, but at 6000K everything will vaporize.

Rather than using a cryogen for cooling you should consider a large block of ice. The latent heat of water is quite impressive.

Offline TakeOff

  • Full Member
  • ***
  • Posts: 353
  • Liked: 73
  • Likes Given: 93
Re: Would a flyby probe to the chromosphere be possible?
« Reply #9 on: 10/08/2017 09:56 AM »
Tungsten or carbon can go up to about 4000K, but at 6000K everything will vaporize.

Rather than using a cryogen for cooling you should consider a large block of ice. The latent heat of water is quite impressive.
Yes, but the exposure time is key. With higher speed more of the core of the probe survives. The temperature of the plasma is maybe not the big problem, because it seems to be pretty sparse, but the heat radiation from the Solar surface might be worse. Earth is 100 Solar radius from the Sun's center. Such a probe would be 1 Solar radius away. So 10 000 times more intense insolation, 14 megawatt per square meter? Or much worse because it's the distance from the surface that counts, not the from center, right?

Some sungrazing comets come arbitrarily close to and into the Sun. I don't know if they can survive touching the transition layer between the chromosphere and the corona. If they are large and rocky enough, I suppose.

Maybe such a comet could be pushed a bit into the most interesting zone, studied before the entry and then again afterwards study what's left of it, and something might be learned from that?


Doing it at the cool Proxima Centauri would be easier, given that a couple of tooth fairies drop by and gets us there.
« Last Edit: 10/08/2017 10:01 AM by TakeOff »

Tags: