xkcd: Sun Avoidance

Post by Lynn McGuire
xkcd: Sun Avoidance
https://www.xkcd.com/3029/
âThe comic shows the end of a table of human missions, both terrestrial
and space-based, ranked by how far they stayed away from the Sun.â
âThis comic was posted the day after December 24, 2024, when the Parker
Solar Probe made its closest approach to the Sun. As a result, it has
set a new record for the worst failure in solar avoidance. This mission
needs to be really close to the Sun so it can make close-up analysis of
its corona and magnetic field. It has been engineered with special solar
shields to protect it from the extreme heat and radiation.â
https://www.explainxkcd.com/wiki/index.php/3029:_Sun_Avoidance
Lynn

"North," murmured the captain. "North."

--
columbiaclosings.com
What's not in Columbia anymore..

Lynn McGuire

2024-12-27 06:03:24 UTC

Post by Lynn McGuire
xkcd: Sun Avoidance
https://www.xkcd.com/3029/
“The comic shows the end of a table of human missions, both terrestrial
and space-based, ranked by how far they stayed away from the Sun.”
“This comic was posted the day after December 24, 2024, when the Parker
Solar Probe made its closest approach to the Sun. As a result, it has
set a new record for the worst failure in solar avoidance. This mission
needs to be really close to the Sun so it can make close-up analysis of
its corona and magnetic field. It has been engineered with special solar
shields to protect it from the extreme heat and radiation.”
https://www.explainxkcd.com/wiki/index.php/3029:_Sun_Avoidance
Lynn

"North," murmured the captain. "North."

What book is that ? Please it is not a book about a whale.

Lynn

Your Name

2024-12-27 06:53:15 UTC

"North," murmured the captain. "North."

What book is that ? Please it is not a book about a whale.
Lynn

Mr Google says it is Ray Bradbury's "The Golden Apples of the Sun",
which is an anthology of 22 short stories, so I don't know which story
it is from.

Paul S Person

2024-12-27 17:07:30 UTC

Post by Lynn McGuire
xkcd: Sun Avoidance
https://www.xkcd.com/3029/
The comic shows the end of a table of human missions, both terrestrial
and space-based, ranked by how far they stayed away from the Sun.
This comic was posted the day after December 24, 2024, when the Parker
Solar Probe made its closest approach to the Sun. As a result, it has
set a new record for the worst failure in solar avoidance. This mission
needs to be really close to the Sun so it can make close-up analysis of
its corona and magnetic field. It has been engineered with special solar
shields to protect it from the extreme heat and radiation.
https://www.explainxkcd.com/wiki/index.php/3029:_Sun_Avoidance
Lynn

"North," murmured the captain. "North."

What book is that ? Please it is not a book about a whale.
Lynn

Mr Google says it is Ray Bradbury's "The Golden Apples of the Sun",
which is an anthology of 22 short stories, so I don't know which story
it is from.

Apparently, my copy only has 18 (it is paired with /R is for Rocket
in, IIRF, a TPB).

I would have researched these pretty fanatically to ensure they had
the same stories as the originals, I think. But I don't appear to have
saved the results, and I suppose I could have missed something.

Sadly, it's been so long since I read them that I can't tell from the
titles which one it was.

Hummm ... possible reading material for my upcoming jury duty? I have
several of these, IIRC. If I actually get onto the jury they might
make the two week (approximately) trial more pleasant.

--
"Here lies the Tuscan poet Aretino,
Who evil spoke of everyone but God,
Giving as his excuse, 'I never knew him.'"

Chris Buckley

2024-12-28 23:06:52 UTC

Post by Paul S Person

"North," murmured the captain. "North."

What book is that ? Please it is not a book about a whale.
Lynn

Mr Google says it is Ray Bradbury's "The Golden Apples of the Sun",
which is an anthology of 22 short stories, so I don't know which story
it is from.

Apparently, my copy only has 18 (it is paired with /R is for Rocket
in, IIRF, a TPB).
I would have researched these pretty fanatically to ensure they had
the same stories as the originals, I think. But I don't appear to have
saved the results, and I suppose I could have missed something.
Sadly, it's been so long since I read them that I can't tell from the
titles which one it was.
Hummm ... possible reading material for my upcoming jury duty? I have
several of these, IIRC. If I actually get onto the jury they might
make the two week (approximately) trial more pleasant.

Interesting. My (standalone) copy has 22 stories; I wonder which were
dropped (or perhaps they were already reprinted in _R is for Rocket_.)

In any case, I'm sure the story in question was not dropped. As Ted
Nolan said, it's in the actual title story "The Golden Apples of the
Sun", which Google may have been referencing.

Chris

Paul S Person

2024-12-29 16:59:36 UTC

Post by Chris Buckley

Post by Paul S Person

Post by Lynn McGuire
xkcd: Sun Avoidance
https://www.xkcd.com/3029/
?The comic shows the end of a table of human missions, both terrestrial
and space-based, ranked by how far they stayed away from the Sun.?
?This comic was posted the day after December 24, 2024, when the Parker
Solar Probe made its closest approach to the Sun. As a result, it has
set a new record for the worst failure in solar avoidance. This mission
needs to be really close to the Sun so it can make close-up analysis of
its corona and magnetic field. It has been engineered with special solar
shields to protect it from the extreme heat and radiation.?
https://www.explainxkcd.com/wiki/index.php/3029:_Sun_Avoidance
Lynn

"North," murmured the captain. "North."

What book is that ? Please it is not a book about a whale.
Lynn

Mr Google says it is Ray Bradbury's "The Golden Apples of the Sun",
which is an anthology of 22 short stories, so I don't know which story
it is from.

Apparently, my copy only has 18 (it is paired with /R is for Rocket
in, IIRF, a TPB).
I would have researched these pretty fanatically to ensure they had
the same stories as the originals, I think. But I don't appear to have
saved the results, and I suppose I could have missed something.
Sadly, it's been so long since I read them that I can't tell from the
titles which one it was.
Hummm ... possible reading material for my upcoming jury duty? I have
several of these, IIRC. If I actually get onto the jury they might
make the two week (approximately) trial more pleasant.

Interesting. My (standalone) copy has 22 stories; I wonder which were
dropped (or perhaps they were already reprinted in _R is for Rocket_.)
In any case, I'm sure the story in question was not dropped. As Ted
Nolan said, it's in the actual title story "The Golden Apples of the
Sun", which Google may have been referencing.

Oh no, both title stories are present.

As to the missing four ... close, but no cigar
Hail and Farewell S Is for Space
Invisible Boy S Is for Space
A Sound of Thunder R Is for Rocket
The Pedestrian S Is for Space
I do have /S Is for Space/ as well, so I have all 22 stories.

Putting two books together like this is, I suppose, one way to make
rather small books look larger and/or justify the price. I have CDs
(mostly 60s folk groups) that have (the songs of) two LPs on them
(grouped by the LP they belong to, and in the original order) for, I
suspect, much the same reason.

--
"Here lies the Tuscan poet Aretino,
Who evil spoke of everyone but God,
Giving as his excuse, 'I never knew him.'"

Peter Fairbrother

2024-12-30 01:31:27 UTC

"North," murmured the captain. "North."

What book is that ? Please it is not a book about a whale.
Lynn

Mr Google says it is Ray Bradbury's "The Golden Apples of the Sun",
which is an anthology of 22 short stories, so I don't know which story
it is from.

The story is "The Golden Apples of the Sun".

"North" is just away from the Sun. They have plucked the apple and can
now go home...

... unlike the Parker Solar Probe, which will if all goes as planned get
close at least twice more, before finally getting close again and
exposing its instruments without shielding, which will destroy them. The
solar shield will then continue orbiting for a few million years.

I kinda feel sorry for it, but I am anthropomorphising too much. However
for some perhaps not-too-distant future AI controlled probes..

Peter Fairbrother

Mad Hamish

2024-12-30 23:16:08 UTC

On Mon, 30 Dec 2024 01:31:27 +0000, Peter Fairbrother

"North," murmured the captain. "North."

What book is that ? Please it is not a book about a whale.
Lynn

Mr Google says it is Ray Bradbury's "The Golden Apples of the Sun",
which is an anthology of 22 short stories, so I don't know which story
it is from.

The story is "The Golden Apples of the Sun".
"North" is just away from the Sun. They have plucked the apple and can
now go home...
... unlike the Parker Solar Probe, which will if all goes as planned get
close at least twice more, before finally getting close again and
exposing its instruments without shielding, which will destroy them. The
solar shield will then continue orbiting for a few million years.
I kinda feel sorry for it, but I am anthropomorphising too much. However
for some perhaps not-too-distant future AI controlled probes..

https://xkcd.com/695/

Christian Weisgerber

2024-12-31 15:44:55 UTC

Post by Mad Hamish

Post by Peter Fairbrother
... unlike the Parker Solar Probe, which will if all goes as planned get
close at least twice more, before finally getting close again and
exposing its instruments without shielding, which will destroy them. The
solar shield will then continue orbiting for a few million years.
I kinda feel sorry for it, but I am anthropomorphising too much. However
for some perhaps not-too-distant future AI controlled probes..

https://xkcd.com/695/

"What is my purpose?"

Rick and Morty - You pass Butter

--
Christian "naddy" Weisgerber ***@mips.inka.de

Cryptoengineer

2025-01-01 04:16:17 UTC

"North," murmured the captain. "North."

What book is that ? Please it is not a book about a whale.
Lynn

Mr Google says it is Ray Bradbury's "The Golden Apples of the Sun",
which is an anthology of 22 short stories, so I don't know which story
it is from.

The story is "The Golden Apples of the Sun".
"North" is just away from the Sun. They have plucked the apple and can
now go home...
... unlike the Parker Solar Probe, which will if all goes as planned get
close at least twice more, before finally getting close again and
exposing its instruments without shielding, which will destroy them. The
solar shield will then continue orbiting for a few million years.
I kinda feel sorry for it, but I am anthropomorphising too much. However
for some perhaps not-too-distant future AI controlled probes..

There's four more perhelions scheduled during 2025. I don't think
there's any plan to deliberately destroy it.

It will fail eventually, but the the solar shield is unlikely to
last long when it's backside gets exposed.

The closest listed perhelion is 6.2 million miles above the surface.
there, the sunlight will be 181x as intense as at Earth orbit.

pt

Peter Fairbrother

2025-01-01 18:00:51 UTC

[...]

Post by Ted Nolan <tednolan>
"North," murmured the captain. "North."

What book is that ? Please it is not a book about a whale.
Lynn

Mr Google says it is Ray Bradbury's "The Golden Apples of the Sun",
which is an anthology of 22 short stories, so I don't know which
story it is from.

The story is "The Golden Apples of the Sun".
"North" is just away from the Sun. They have plucked the apple and can
now go home...
... unlike the Parker Solar Probe, which will if all goes as planned
get close at least twice more, before finally getting close again and
exposing its instruments without shielding, which will destroy them.
The solar shield will then continue orbiting for a few million years.
I kinda feel sorry for it, but I am anthropomorphising too much.
However for some perhaps not-too-distant future AI controlled probes..

There's four more perihelions scheduled during 2025. I don't think
there's any plan to deliberately destroy it.

The primary mission ends after two more close passes, iirc perihelia 23
and 24, in March and June this year (2025). Both of these will be at the
same 6.2 million kilometres from the Sun as the recent pass.

After that it depends on onboard fuel, and Parker's fate has not been
decided: they may well extend the mission and keep it going as-is for
several years, using the remaining fuel for attitude adjustment (needed
for both approaching the Sun and to get data back). I don't know whether
there is any chance of another Venus gravity assist and getting even
closer to the Sun, but that would be fun if possible.

However there is an end-of-life contingency plan to directly expose the
instruments as the fuel runs out and get some other data. I don't know
how they intend to get the data back afterwards, but doing so is part of
that plan.

It will fail eventually, but the the solar shield is unlikely to
last long when it's backside gets exposed.

I don't think that will make much difference, though I haven't done any
detailed analysis of the question. Carbon-carbon is black and absorbs
sunlight better than the white alumina coating, but that coating only
gets to 1,400C at closest approach.

The carbon-carbon heatshield can get to over 3000K before melting. The
alumina coating would melt at about 2100C. They put the coating on to
decrease total heat flux and keep the back of the heatshield at 300C
rather than to limit the working temperature of the carbon-carbon. Also
the coating is lighter than the extra thickness of carbon foam
insulation which would be needed if the coating wasn't there.

If it stayed close to the Sun all the time then the protons in the solar
wind might be a chemistry problem with the carbon, but as they are only
close to the Sun for an hour or so every three months I think it might
last a few million years.

The heatshield is pretty fluffy and might get blown about by solar winds.

Someone at NASA said a few billion years, but that is anther question.

Peter Fairbrother

Cryptoengineer

2025-01-01 19:59:27 UTC

Post by Peter Fairbrother
[...]

Post by Ted Nolan <tednolan>
"North," murmured the captain. "North."

What book is that ? Please it is not a book about a whale.
Lynn

Mr Google says it is Ray Bradbury's "The Golden Apples of the Sun",
which is an anthology of 22 short stories, so I don't know which
story it is from.

The story is "The Golden Apples of the Sun".
"North" is just away from the Sun. They have plucked the apple and
can now go home...
... unlike the Parker Solar Probe, which will if all goes as planned
get close at least twice more, before finally getting close again and
exposing its instruments without shielding, which will destroy them.
The solar shield will then continue orbiting for a few million years.
I kinda feel sorry for it, but I am anthropomorphising too much.
However for some perhaps not-too-distant future AI controlled probes..

There's four more perihelions scheduled during 2025. I don't think
there's any plan to deliberately destroy it.

The primary mission ends after two more close passes, iirc perihelia 23
and 24, in March and June this year (2025). Both of these will be at the
same 6.2 million kilometres from the Sun as the recent pass.
After that it depends on onboard fuel, and Parker's fate has not been
decided: they may well extend the mission and keep it going as-is for
several years, using the remaining fuel for attitude adjustment (needed
for both approaching the Sun and to get data back). I don't know whether
there is any chance of another Venus gravity assist and getting even
closer to the Sun, but that would be fun if possible.
However there is an end-of-life contingency plan to directly expose the
instruments as the fuel runs out and get some other data. I don't know
how they intend to get the data back afterwards, but doing so is part of
that plan.

It will fail eventually, but the the solar shield is unlikely to
last long when it's backside gets exposed.

I don't think that will make much difference, though I haven't done any
detailed analysis of the question. Carbon-carbon is black and absorbs
sunlight better than the white alumina coating, but that coating only
gets to 1,400C at closest approach.
The carbon-carbon heatshield can get to over 3000K before melting. The
alumina coating would melt at about 2100C. They put the coating on to
decrease total heat flux and keep the back of the heatshield at 300C
rather than to limit the working temperature of the carbon-carbon. Also
the coating is lighter than the extra thickness of carbon foam
insulation which would be needed if the coating wasn't there.
If it stayed close to the Sun all the time then the protons in the solar
wind might be a chemistry problem with the carbon, but as they are only
close to the Sun for an hour or so every three months I think it might
last a few million years.
The heatshield is pretty fluffy and might get blown about by solar winds.
Someone at NASA said a few billion years, but that is anther question.

Thanks. Interesting!

pt

Ted Nolan <tednolan>

2024-12-27 22:19:46 UTC