"“Dark Fall” by David Weber"

[Lynn McGuire]

"“Dark Fall” by David Weber"
https://www.baen.com/darkfall

"Brave New World"

"Four centuries ago, the Calvin’s Hope set out from Earth. On board,
colonists who knew they themselves would never again set foot on a
planet’s surface, but who hoped for a better life for their descendants,
away from the Earth Union’s corrupt politics. Now, generations later,
Calvin’s Hope is about to reach its destination. KCR-126-04 looked to be
the perfect system for the colonists’ new homeworld. The planet on which
they planned to live was referred to as “Earth’s twin.” But that was
before the Hammers fell. Two asteroids, both larger than the one that
drove the dinosaurs to extinction, have rendered the planet
uninhabitable. Light-years from Earth and with no hope of turning back,
it seems all is lost for the crew of Calvin’s Hope. But though all seems
lost, Captain Vincent Anderson and his crew aren’t ready to roll over.
They’ve come this far—now they’ll make their own luck."

"A new novella set in David Weber’s Honorverse! Read “Dark Fall” here."

Hat tip to:
http://baen.com/newsletter/09-2018_2.html

Lynn

[Robert Carnegie]

Post by Lynn McGuire
"“Dark Fall” by David Weber"
https://www.baen.com/darkfall
"Brave New World"
"Four centuries ago, the Calvin’s Hope set out from Earth. On board,
colonists who knew they themselves would never again set foot on a
planet’s surface, but who hoped for a better life for their descendants,
away from the Earth Union’s corrupt politics. Now, generations later,
Calvin’s Hope is about to reach its destination. KCR-126-04 looked to be
the perfect system for the colonists’ new homeworld. The planet on which
they planned to live was referred to as “Earth’s twin.” But that was
before the Hammers fell. Two asteroids, both larger than the one that
drove the dinosaurs to extinction, have rendered the planet
uninhabitable. Light-years from Earth and with no hope of turning back,
it seems all is lost for the crew of Calvin’s Hope. But though all seems
lost, Captain Vincent Anderson and his crew aren’t ready to roll over.
They’ve come this far—now they’ll make their own luck."
"A new novella set in David Weber’s Honorverse! Read “Dark Fall” here."
http://baen.com/newsletter/09-2018_2.html
Lynn

Two dinosaur-killer asteroids? How unlucky can you get!

On the plus side, you shouldn't have pesky dinosaurs
to deal with.

I gather that current thinking about the impact on Earth -
if we're talking about an impact - is that material at
the impact was ejected back into space, then fell back all
over the turning world, leading scientists to compare
the heat of the sky to the interior of your kitchen oven
(unless you have a microwave).

So, ouch.

[Greg Goss]

they planned to live was referred to as “Earth’s twin.” But that was

Post by Lynn McGuire
before the Hammers fell. Two asteroids, both larger than the one that
drove the dinosaurs to extinction, have rendered the planet
uninhabitable.

Two dinosaur-killer asteroids? How unlucky can you get!

It could have started as one even bigger asteroid that broke apart
from tidal forces on a previous near pass. See Shoemaker-Levy.

On the plus side, you shouldn't have pesky dinosaurs
to deal with.
I gather that current thinking about the impact on Earth -
if we're talking about an impact - is that material at
the impact was ejected back into space, then fell back all
over the turning world, leading scientists to compare
the heat of the sky to the interior of your kitchen oven
(unless you have a microwave).
So, ouch.

"Set the sky on BAKE"

The land animal classes that survived could plausibly all have been
burrowing species.

You have a generatiion ship. Wait another generaton and you begin to
have a viable ecosystem again.

[Bernard Peek]

Post by Greg Goss
You have a generatiion ship. Wait another generaton and you begin to
have a viable ecosystem again.

It depends how long it takes for the dust to settle. Nature is amazingly
resilient. But I would expect a generation ship to be carrying enough
supplies to be able to kick-start the local ecology.

But any planet that already has an oxygen/nitrogen atmosphere probably
already has enough local microbes to be uninhabitable.

[David Johnston]

Post by Bernard Peek

You have a generatiion ship.  Wait another generaton and you begin to
have a viable ecosystem again.

It depends how long it takes for the dust to settle. Nature is amazingly
resilient. But I would expect a generation ship to be carrying enough
supplies to be able to kick-start the local ecology.
But any planet that already has an oxygen/nitrogen atmosphere probably
already has enough local microbes to be uninhabitable.

I do not agree that local microbes equate to uninhabitability

[Dorothy J Heydt]

Post by David Johnston

Post by Bernard Peek

You have a generatiion ship.  Wait another generaton and you begin to
have a viable ecosystem again.

It depends how long it takes for the dust to settle. Nature is amazingly
resilient. But I would expect a generation ship to be carrying enough
supplies to be able to kick-start the local ecology.
But any planet that already has an oxygen/nitrogen atmosphere probably
already has enough local microbes to be uninhabitable.

I do not agree that local microbes equate to uninhabitability

Depends on whether their biochemistry is sufficiently similar to
your own that they can infect you.

[David Johnston]

Post by Dorothy J Heydt

Post by David Johnston

Post by Bernard Peek

You have a generatiion ship.  Wait another generaton and you begin to
have a viable ecosystem again.

It depends how long it takes for the dust to settle. Nature is amazingly
resilient. But I would expect a generation ship to be carrying enough
supplies to be able to kick-start the local ecology.
But any planet that already has an oxygen/nitrogen atmosphere probably
already has enough local microbes to be uninhabitable.

I do not agree that local microbes equate to uninhabitability

Depends on whether their biochemistry is sufficiently similar to
your own that they can infect you.

Not really. While I can certainly imagine that by some fluke local
microfauna can infect humans with a high degree of lethality perhaps
because it excretes something that's a nerve agent to us, it would be a
fluke. More likely what he had in mine is that the incompatibility of
local biochemistry would lead to it being impossible to establish our
own plant life and grow food in the open, but I don't agree.

[Bernard Peek]

Post by Dorothy J Heydt

Post by David Johnston
I do not agree that local microbes equate to uninhabitability

Depends on whether their biochemistry is sufficiently similar to
your own that they can infect you.

Not really.  While I can certainly imagine that by some fluke local
microfauna can infect humans with a high degree of lethality perhaps
because it excretes something that's a nerve agent to us, it would be a
fluke.  More likely what he had in mine is that the incompatibility of
local biochemistry would lead to it being impossible to establish our
own plant life and grow food in the open, but I don't agree.

The majority of microfauna won't be a problem, no more so than the
majority of the bacteria that live in our soil worry us. But the notion
that none of them could infect us is extremely dubious. The longer we
remain exposed to them the higher the probability that one or more will
evolve to take advantage of the new ecological niche. In the long run
it's almost certain.

The local biochemistry might be quite different to ours, different
chirality etc. But bacteria here already have the capability to
metabolise molecules that they rarely encounter and in an alien
environment some of them are likely to just activate alternative
metabolic pathways and carry on feeding.

In short, most of our bacteria would probably find it difficult or
impossible to live on alien hosts. But the probability that none of them
could is close to zero and falls further with time. The same applies to
alien bugs infecting us.

[David Johnston]

Post by Bernard Peek

Post by Dorothy J Heydt

Post by David Johnston
I do not agree that local microbes equate to uninhabitability

Depends on whether their biochemistry is sufficiently similar to
your own that they can infect you.

Not really.  While I can certainly imagine that by some fluke local
microfauna can infect humans with a high degree of lethality perhaps
because it excretes something that's a nerve agent to us, it would be
a fluke.  More likely what he had in mine is that the incompatibility
of local biochemistry would lead to it being impossible to establish
our own plant life and grow food in the open, but I don't agree.

The majority of microfauna won't be a problem, no more so than the
majority of the bacteria that live in our soil worry us. But the notion
that none of them could infect us is extremely dubious. The longer we
remain exposed to them the higher the probability that one or more will
evolve to take advantage of the new ecological niche. In the long run
it's almost certain.

Even if that's true, by that standard Earth is uninhabitable.

[J. Clarke]

Post by Bernard Peek

Post by Dorothy J Heydt

Post by David Johnston
I do not agree that local microbes equate to uninhabitability

Depends on whether their biochemistry is sufficiently similar to
your own that they can infect you.

Not really.  While I can certainly imagine that by some fluke local
microfauna can infect humans with a high degree of lethality perhaps
because it excretes something that's a nerve agent to us, it would be a
fluke.  More likely what he had in mine is that the incompatibility of
local biochemistry would lead to it being impossible to establish our
own plant life and grow food in the open, but I don't agree.

The majority of microfauna won't be a problem, no more so than the
majority of the bacteria that live in our soil worry us. But the notion
that none of them could infect us is extremely dubious. The longer we
remain exposed to them the higher the probability that one or more will
evolve to take advantage of the new ecological niche. In the long run
it's almost certain.
The local biochemistry might be quite different to ours, different
chirality etc. But bacteria here already have the capability to
metabolise molecules that they rarely encounter and in an alien
environment some of them are likely to just activate alternative
metabolic pathways and carry on feeding.
In short, most of our bacteria would probably find it difficult or
impossible to live on alien hosts. But the probability that none of them
could is close to zero and falls further with time. The same applies to
alien bugs infecting us.

It could happen but our own bugs infect us and the world doesn't end,
so why would alien bugs doing the same be worse?

[Kevrob]

Post by J. Clarke
It could happen but our own bugs infect us and the world doesn't end,
so why would alien bugs doing the same be worse?

There could be other problems, such as exolife exuding or
excreting substances highly toxic to us, making them unsafe
to even handle without suitable protective gear.

Kevin R

[J. Clarke]

Post by Kevrob

Post by J. Clarke
It could happen but our own bugs infect us and the world doesn't end,
so why would alien bugs doing the same be worse?

There could be other problems, such as exolife exuding or
excreting substances highly toxic to us, making them unsafe
to even handle without suitable protective gear.

There is plenty of Earth life that "exudes substances highly toxic to
us". Hasn't ended the world.

[Bernard Peek]

Post by J. Clarke

Post by Bernard Peek
In short, most of our bacteria would probably find it difficult or
impossible to live on alien hosts. But the probability that none of them
could is close to zero and falls further with time. The same applies to
alien bugs infecting us.

It could happen but our own bugs infect us and the world doesn't end,
so why would alien bugs doing the same be worse?

There's no guarantee that our immune systems would be able to recognise
alien antigens or that our defence systems could kill them. We probably
wouldn't have any antibiotics available either. While the aliens might
have effective antibiotics safe for their own metabolism they would be
untested in ours. We could probably develop new antibiotics but that
would take time.

[Dimensional Traveler]

Post by Bernard Peek

Post by J. Clarke

Post by Bernard Peek
In short, most of our bacteria would probably find it difficult or
impossible to live on alien hosts. But the probability that none of them
could is close to zero and falls further with time. The same applies to
alien bugs infecting us.

It could happen but our own bugs infect us and the world doesn't end,
so why would alien bugs doing the same be worse?

There's no guarantee that our immune systems would be able to recognise
alien antigens or that our defence systems could kill them. We probably
wouldn't have any antibiotics available either. While the aliens might
have effective antibiotics safe for their own metabolism they would be
untested in ours. We could probably develop new antibiotics but that
would take time.

We have our own antibiotic resistant bugs infecting us and the world
doesn't end, so why would alien bugs doing the same be worse?

[David DeLaney]

Post by Dimensional Traveler
We have our own antibiotic resistant bugs infecting us and the world
doesn't end, so why would alien bugs doing the same be worse?

Yabbut that means one by one OUR worlds end.

Dave, use antibiotics RESPONSIBLY kids, they don't grow on TREES

[J. Clarke]

On Fri, 28 Sep 2018 04:33:12 -0500, David DeLaney

Post by David DeLaney

Post by Dimensional Traveler
We have our own antibiotic resistant bugs infecting us and the world
doesn't end, so why would alien bugs doing the same be worse?

Yabbut that means one by one OUR worlds end.
Dave, use antibiotics RESPONSIBLY kids, they don't grow on TREES

OUR worlds end regardless. Anybody who thinks otherwise is
delusional. Nobody lives forever so make the most of the time you've
got.

[David Johnston]

Post by Bernard Peek

Post by J. Clarke

Post by Bernard Peek
In short, most of our bacteria would probably find it difficult or
impossible to live on alien hosts. But the probability that none of them
could is close to zero and falls further with time. The same applies to
alien bugs infecting us.

It could happen but our own bugs infect us and the world doesn't end,
so why would alien bugs doing the same be worse?

There's no guarantee that our immune systems would be able to recognise
alien antigens or that our defence systems could kill them.

If they could recognize our cells as yummy and delectable then they are
going to be similar enough that our defense systems ought to be able to
do something about them. And even apart from that such a micro-organism
is extremely unlikely to be spread over the entire planet in every biome.

[Robert Carnegie]

Post by David Johnston

Post by Bernard Peek

Post by J. Clarke

Post by Bernard Peek
In short, most of our bacteria would probably find it difficult or
impossible to live on alien hosts. But the probability that none of them
could is close to zero and falls further with time. The same applies to
alien bugs infecting us.

It could happen but our own bugs infect us and the world doesn't end,
so why would alien bugs doing the same be worse?

There's no guarantee that our immune systems would be able to recognise
alien antigens or that our defence systems could kill them.

If they could recognize our cells as yummy and delectable then they are
going to be similar enough that our defense systems ought to be able to
do something about them. And even apart from that such a micro-organism
is extremely unlikely to be spread over the entire planet in every biome.

When an aggressive infectious organism on Earth
finds a relatively new population of humans to
play in... sometimes there aren't many survivors.
Although some cases I'm thinking of are viruses,
which arguably aren't alive, and are basically
hacks against the human body itself. Unlikely
to be found on other worlds unless you hold to
panspermia. Otherwise - well, spoilers: it's
what Earth did to the Martians in _The War of
the Worlds_.

[Kevrob]

Post by Robert Carnegie

Post by David Johnston

Post by Bernard Peek

Post by J. Clarke

Post by Bernard Peek
In short, most of our bacteria would probably find it difficult or
impossible to live on alien hosts. But the probability that none of them
could is close to zero and falls further with time. The same applies to
alien bugs infecting us.

It could happen but our own bugs infect us and the world doesn't end,
so why would alien bugs doing the same be worse?

There's no guarantee that our immune systems would be able to recognise
alien antigens or that our defence systems could kill them.

If they could recognize our cells as yummy and delectable then they are
going to be similar enough that our defense systems ought to be able to
do something about them. And even apart from that such a micro-organism
is extremely unlikely to be spread over the entire planet in every biome.

When an aggressive infectious organism on Earth
finds a relatively new population of humans to
play in... sometimes there aren't many survivors.
Although some cases I'm thinking of are viruses,
which arguably aren't alive, and are basically
hacks against the human body itself. Unlikely
to be found on other worlds unless you hold to
panspermia. Otherwise - well, spoilers: it's
what Earth did to the Martians in _The War of
the Worlds_.

Several SF writers have used the idea of a virgin field
epidemic/pandemic to depopulate an area colonists arrived
at. The one closest to the Terran "New World" experience
a la the Columbian explorations at the end of the 15th
century CE would be Stirling's Nantucket novels.

Kevin R

[Mike Van Pelt]

Post by Bernard Peek
There's no guarantee that our immune systems would be able to recognise
alien antigens or that our defence systems could kill them.

On the other hand, our immune systems are pretty much geared
to attack anything that looks "foreign." Disease-causing
microbes have various tricks to "not look foreign."

Alien bacteria would look really *really* foreign. I suspect
our immune systems would be all over them really quickly.

The bigger danger might be immune system overreaction.
Cytokine storm is what killed most of the victims of the
1918 influenza epidemic, not the virus itself. (Which is
why it was so especially deadly to young, vigorous, healthy
people.)

[J. Clarke]

Post by Bernard Peek

Post by J. Clarke

Post by Bernard Peek
In short, most of our bacteria would probably find it difficult or
impossible to live on alien hosts. But the probability that none of them
could is close to zero and falls further with time. The same applies to
alien bugs infecting us.

It could happen but our own bugs infect us and the world doesn't end,
so why would alien bugs doing the same be worse?

There's no guarantee that our immune systems would be able to recognise
alien antigens or that our defence systems could kill them. We probably
wouldn't have any antibiotics available either. While the aliens might
have effective antibiotics safe for their own metabolism they would be
untested in ours. We could probably develop new antibiotics but that
would take time.

The trick the bug has to pull off is convincing the immune system that
it's _not_ a foreign substance. While there's a part of the immune
system that works on specific bugs based on pattern recognition,
there's another part that just recognizes "not invented here" and goes
to town.,

And what "aliens"? Another planet with bugs is not necessarily going
to have a civilization.

[J. Clarke]

Post by Dorothy J Heydt

Post by David Johnston

Post by Bernard Peek

You have a generatiion ship.  Wait another generaton and you begin to
have a viable ecosystem again.

It depends how long it takes for the dust to settle. Nature is amazingly
resilient. But I would expect a generation ship to be carrying enough
supplies to be able to kick-start the local ecology.
But any planet that already has an oxygen/nitrogen atmosphere probably
already has enough local microbes to be uninhabitable.

I do not agree that local microbes equate to uninhabitability

Depends on whether their biochemistry is sufficiently similar to
your own that they can infect you.

If they aren't specialized to deal with our defenses they just die.
Every microbe that exists on Earth doesn't infect humans. Just a few
specialists.

[David DeLaney]

Post by J. Clarke

Post by Dorothy J Heydt

Post by David Johnston

Post by Bernard Peek
But any planet that already has an oxygen/nitrogen atmosphere probably
already has enough local microbes to be uninhabitable.

I do not agree that local microbes equate to uninhabitability

Depends on whether their biochemistry is sufficiently similar to
your own that they can infect you.

If they aren't specialized to deal with our defenses they just die.
Every microbe that exists on Earth doesn't infect humans. Just a few
specialists.

Yep. Our cells have evolved to be killing microwords.

Dave, skin, the miracle covering!

[Greg Goss]

Post by Bernard Peek

Post by Greg Goss
You have a generatiion ship. Wait another generaton and you begin to
have a viable ecosystem again.

It depends how long it takes for the dust to settle. Nature is amazingly
resilient. But I would expect a generation ship to be carrying enough
supplies to be able to kick-start the local ecology.
But any planet that already has an oxygen/nitrogen atmosphere probably
already has enough local microbes to be uninhabitable.

I've read partway through the story. I found the thirteen century
jump disconcerting.

But those thirteen centures answer my "wait another generation"
comment.

"What they did know was that even today, thirteen standard centuries
later, Calvin III was a bleak, barren place whose shattered ecosystem
had scarcely begun to heal. In fact, most climatologists and
biologists leaned towards the theory that what they were observing
wasn’t a recovery at all, simply the final throes and death rattle of
an entire planet’s slow, lingering murder."

[Greg Goss]

Post by Greg Goss
"What they did know was that even today, thirteen standard centuries
later, Calvin III was a bleak, barren place whose shattered ecosystem
had scarcely begun to heal. In fact, most climatologists and
biologists leaned towards the theory that what they were observing
wasn’t a recovery at all, simply the final throes and death rattle of
an entire planet’s slow, lingering murder."

I'm still skeptical. Life is versatile and evolution can move fast
when niches are new or otherwise empty.

I don't think I believe in ecosystem "throes". Either it's
sterilized, or enough of an ecosystem will spread into the blank
planet.

[f***@gmail.com]

Greets,

Greg Goss wrote on Sep 14

You have a generation ship. Wait another generation and you begin to
have a viable ecosystem again.

If you follow the link provided to the teaser material you'll read that the ship is finished. It's worn out and breaking down. It was only designed to last the duration of the trip and the immediate period needed for landing. The engineer(s) think they can drag out the life expectancy no more than 20 years.

Not the brightest way to plan your mission, especially seeing as you have no guarantees about how safe the planet will be when you arrive. Seems to be a re-occurring meme in stories involving generation ships.

At the very least a generation ship mission should be planning for a millennium or two orbiting the destination planet while cleaning up or establishing your biosphere is finished.

Anyway, take care.
Regards
Frank

[David Johnston]

Post by f***@gmail.com
Greets,
Greg Goss wrote on Sep 14

You have a generation ship. Wait another generation and you begin to
have a viable ecosystem again.

If you follow the link provided to the teaser material you'll read that the ship is finished. It's worn out and breaking down. It was only designed to last the duration of the trip and the immediate period needed for landing. The engineer(s) think they can drag out the life expectancy no more than 20 years.
Not the brightest way to plan your mission, especially seeing as you have no guarantees about how safe the planet will be when you arrive. Seems to be a re-occurring meme in stories involving generation ships.
At the very least a generation ship mission should be planning for a millennium or two orbiting the destination planet while cleaning up or establishing your biosphere is finished.

Generation ships are a ridiculous enough concept without hauling enough
extra mass to sustain another thousand years in space.

[Default User]

Post by David Johnston

Post by f***@gmail.com
Greets,
At the very least a generation ship mission should be planning for
a millennium or two orbiting the destination planet while cleaning
up or establishing your biosphere is finished.

Generation ships are a ridiculous enough concept without hauling
enough extra mass to sustain another thousand years in space.

The most recent novel by Becky Chambers, set in her "Wayfarer"
universe, has generation ships that not didn't lose purpose or fall
apart, but are still going.

After contact with the "Galactic Commons" and acceptance of humans into
that, those that wanted to settle on alien planets or homestead empty
planet have been doing that. Others remain on the ships in their new
parking orbit around an empty-ish star and keep living life more or
less as during the voyage.


Brian

[Greg Goss]

Post by Default User

Post by David Johnston

Post by f***@gmail.com
Greets,
At the very least a generation ship mission should be planning for
a millennium or two orbiting the destination planet while cleaning
up or establishing your biosphere is finished.

Generation ships are a ridiculous enough concept without hauling
enough extra mass to sustain another thousand years in space.

The most recent novel by Becky Chambers, set in her "Wayfarer"
universe, has generation ships that not didn't lose purpose or fall
apart, but are still going.
After contact with the "Galactic Commons" and acceptance of humans into
that, those that wanted to settle on alien planets or homestead empty
planet have been doing that. Others remain on the ships in their new
parking orbit around an empty-ish star and keep living life more or
less as during the voyage.

Niven/Pournelle's Footfall has this as a subtheme. The aliens arrive
on a generation ship with many "frozen" individuals. The frozen ones,
with command seniority, grew up on a planet and want to colonize the
new one (ours). The spaceborn, who have lived all their lives on the
ship want to ignore planets and continue living in space.

[Thomas Koenig]

Post by Greg Goss
Niven/Pournelle's Footfall has this as a subtheme. The aliens arrive
on a generation ship with many "frozen" individuals. The frozen ones,
with command seniority, grew up on a planet and want to colonize the
new one (ours). The spaceborn, who have lived all their lives on the
ship want to ignore planets and continue living in space.

If I remember correctly, the frozen ones thought that they would
have seniority, but they were compelled to surrender upon awakening.
It was a rude surprise for them.

Both factions wanted to colonize Earth.

[J. Clarke]

On Sun, 23 Sep 2018 17:04:36 -0000 (UTC), Thomas Koenig

Post by Thomas Koenig

Post by Greg Goss
Niven/Pournelle's Footfall has this as a subtheme. The aliens arrive
on a generation ship with many "frozen" individuals. The frozen ones,
with command seniority, grew up on a planet and want to colonize the
new one (ours). The spaceborn, who have lived all their lives on the
ship want to ignore planets and continue living in space.

If I remember correctly, the frozen ones thought that they would
have seniority, but they were compelled to surrender upon awakening.
It was a rude surprise for them.
Both factions wanted to colonize Earth.

FWIW, if you want to try a short but somewhat interesting game, look
for "Analogue: A Hate Story". The plot can be summarized as: "FTL
traveler encounters generation ship, finds things went wrong". Beyond
that would be spoilery.

[Default User]

Post by Thomas Koenig

Post by Greg Goss
Niven/Pournelle's Footfall has this as a subtheme. The aliens
arrive on a generation ship with many "frozen" individuals. The
frozen ones, with command seniority, grew up on a planet and want
to colonize the new one (ours). The spaceborn, who have lived all
their lives on the ship want to ignore planets and continue living
in space.

If I remember correctly, the frozen ones thought that they would
have seniority, but they were compelled to surrender upon awakening.
It was a rude surprise for them.

Similar to Niven's A Gift From Earth, enacted with humans.


Brian