Math needed for 5-week flight from Earth to Mars

[Staiduk]

Looks like something drawn by Jules Verne.

(chuckle) It does rather, doesn't it? At least it doesn't look like the Yamato - however totally and completely cool that ship was!

Mars rover confirms dangers of space radiation.
Future manned missions to Mars will need internal shielding and advanced propulsion systems to shorten transit times, minimizing exposure to space radiation, scientists say.
by William Harwood May 30, 2013 3:06 PM PDT

http://news.cnet.com/8301-11386_3-57586958-76/mars-rover-confirms-dangers-of-space-radiation/

An expensive and far off development using nuclear propulsion that is already controversial and would still only make the travel time 6 months(!)
This is a big reason why I argue for getting the propellant from the Moon. Then we would have virtually unlimited amount of propellant to drastically cut the travel time, no new, expensive, (potentially) dangerous, far off propulsion systems required.

Then a manned Mars mission is simply dependent on setting up a propellant production base on the Moon. Since as I argue manned/cargo lunar flights can be done at costs of a few hundred million per flight, making multiple flights per year possible, constructing such as base and therefore mounting a Mars mission can be done in less than a decade.

Bob Clark

I love how the vast majority of this thread is way, way over my head - aside from how much I'm learning its nice I've actually been able to ask something that has interested smart people. I can't offer much about the mathematics, but can interject here since Mr. Clark got the basic outline of how I set up my future Solar System spot on.

Spaceflight in Kylie's universe is dependant upon four Habitats in sychronous orbit over their respective worlds. These space stations are huge orbiting cities; destinations for travel and tourism in and of themselves, the largest (High Heaven, orbiting Earth) more than fifteen kilometers in length with a current population of 1.2 million. Each Habitat has additional duties given their placement. High Heaven is the main fuelling, loading and servicing port for all Solar System shipping. All large ships leaving Earth make port at HH to be serviced, fuelled and loaded with cargo before heading to their destinations. As such she also is the primary center for command, control and security of all Solar System flight.

Lunar Haven orbiting the Moon is only slightly smaller at 13kms. and serves the Moon's burgeoning population.
The Moon's primary purpose is heavy manufacturing and mining - so much so that 3M moved its principle headquarters and factories there from Minnesota; keeping the trademark but changing the first word in the name. Much mining is centered around fuel production. I'm not exactly sure what fuel is produced; if it is as simple as oxy/hydrogen or something a bit more exotic. But either way, the Moon produces fuel which is sent via catapult to Lunar Haven; which sends it in huge tankers about the Solar System; most heading to High Heaven and Earth. (Side note: The Moon also sends energy directly to Earth in the form of a microwave beam; which supplies a good part of the home planet's energy needs. Politics ensues. )
So basically fuel comes in to High Heaven from the Moon via Lunar Haven, shipping comes into HH and is sent from there - well; just about anywhere they want to go.

Next in line is the smaller - but still huge at 10km. - Nouvelle Paris (pop. 350,000) over Mars; serving the Jovian system and that planet's small (100,000) but growing population. (New Paris - true to her terrestrial roots - also serves as a cultural and artistic bastion in the pragmatic, practical Outer Colonies. Food, art, theatre and beauty are highly prized. If you're smart enough to realize this opens the door to the black market and organized crime; you'll be able to understand just how dynamic and adventurous life in "The Far France" can be. )

Fourth and last is Angelhome over Venus - a much smaller 3km. Stanford Torus design. Originally a research station, now an independant - and independantly minded - community of ex-pats, researchers, adventure-seekers and artists; with a population of perhaps 80,000.

A fifth Habitat - another Torus - destined for Ganymede is currently being built in Lunar orbit and primary construction is expected to be finished within the next 30 years. Outfitting and interior construction will be completed by Martian facilities once those facilities are built and the as-yet-unnamed Torus (the working title is Clarkestowne after the ancient author that inspired so much of spaceflight) towed to Mars.

Yeah, OK - I got a little carried away but I'm having such fun with my personal Solar System. :thumbup: My goal was to design Human expansion in the most logical and realistic way possible, including the expected explosion of extra-terrestrial settlement once conditions are ripe. Thus Bob Clark's comments regarding Lunar fuel production are spot-on in terms of my solar system. Heck - we've got a great big piece of undeveloped ground just sitting there three days away - let's use the bloody thing!

Cheers!

---------- Post added at 09:10 PM ---------- Previous post was at 04:07 PM ----------

Hmm... while writing the bit about Angelhome; I realized this might be a good place to ask another question. Angelhome was originally built as a research station; and as a waystation in a strategically valuable position. It has since - in the fifty years it has been populated - become an active and dynamic independant culture where art, philosophy and scientific study are prized.
But to be 'independant', it must be able to support itself. I intended Angelhome to be at the back-end of civilization; a shining jewel in the darkness. Angelhome is a place to go to; not come from. The thing is, its location over Venus doesn't give it very much either in terms of natural resources or valuable position. That's why I put it there. But I didn't think hard enough about whether or not Angelhome would have any chance of succeeding.

As far as I can see; the only natural resources Angelhome can make use of are sunlight, carbon dioxide and sulfuric acid. In order to be independant, a colony must be able to give back as much - perhaps in different coin - as it takes in. Angelhome is highly agrarian; much of its inner surface dedicated to farming. Extensive underground farms - some twenty levels deep - also produce huge amounts of food and other bioproducts. With this info; can anyone imagine how Angelhome - a Stanford Torus in synchronous orbit over Venus; with a normal population of 160,000 - would become a self-sufficient, independant colony? "It just is" is not good enough; I've tried to develop my solar system with economic, cultural and societal terms in mind.
Thanx!

 

[dgatsoulis]

Can anyone imagine how Angelhome - a Stanford Torus in synchronous orbit over Venus; with a normal population of 160,000 - would become a self-sufficient, independant colony? "It just is" is not good enough; I've tried to develop my solar system with economic, cultural and societal terms in mind.
Thanx!

Sorry but the tone of this post will be "It just is". No I don't want to be the bearer of bad news, but by identifying the problems with the existence of "Angelhome" in a not-so-distant future, we can take steps to solve them.

You cannot have Angelhome on a [ame="http://en.wikipedia.org/wiki/Synchronous_orbit"]synchronous orbit[/ame] around Venus, because no such orbit exists. A synchronous orbit is one that has a period equal to the average rotational period of the body being orbited and in the same direction of rotation as that body.

A Venusian [ame="http://simple.wikipedia.org/wiki/Sidereal_day"]siderial day[/ame] (the time it takes Venus to rotate exactly 360° around its axis) is 243 Earth days long. In fact, a Venusian year (224,65 Earth days) is smaller than a Venusian day.

Math don't lie.
We can easily calculate the distance needed from the center of the planet for a synchronous orbit around Venus:

[math] R = \left(\frac{T^2GM}{4\pi^2}\right)^{1/3}[/math]
(Where R is the distance from the center of the planet, T is the orbital period, G is the gravitational constant and M is Venus' mass.)

Convert the days to seconds and plugin Venus' mass in kg. The result will be in meters from the center of the planet.

(Source for Venusian siderial day and mass, Orbiter\Config\Venus.cfg)

The result is ~7.07 billion meters or 7.07 million km. Venus' Sphere of influence extends only to about 616 thousand km, so it's impossible to place an object around Venus in an orbit with such a long period.

That said, I don't see the benefit of a synchronous orbit around Venus even if such an orbit existed. For Earth, the synchronous orbit, is the altitude we place our communications satellites because we have ground stations/antennas/dishes and it's handy to bounce a signal by always aiming at the same direction in the sky.

The hellish Venusian environment means no ground stations. No ground stations, no need for a synchronous orbit.

Now to the self-sustained part. I guess it depends on your definition of self sustained. After all, I can't think of any city on Earth that is self-sustained, why should one orbiting Venus be?

Suppose that you build the station with everything transported from Earth and you try to make it so that all the food is produced there by the farms you mentioned. What about water? metal alloys? plastics?. Even with very evolved 3D printers and a very high recycling factor, you still need the raw materials. Unfortunately those materials don't exist near Venus. The composition of the atmosphere and the surface conditions make any attempt to get at least some (metals?) directly from it extremely difficult.

The only thing that comes to mind, would be the capture of an asteroid or more and placement in a convenient orbit. Then your raw material needs could be covered.

The problem is that at that distance from the Sun, I don't expect asteroids with water ice. It would have vaporized millions of years ago.

Perhaps some NVOs (Near-Venus-Objects), -asteroids that pass regularly near Venus- and the discovery of a few very lucrative ones in terms of composition (high concetrations of platinum group metals) would make Angelhome worth the trouble of building and sustaining it.

It also means the shift of your hypothetical economy from agricultural (not much water, so not much crops) to an asteroid mining one. (Sell precious metals and other ores to get life sustaining water).

Anyway, just my :2cents:

 

[Staiduk]

Sorry but the tone of this post will be "It just is". No I don't want to be the bearer of bad news, but by identifying the problems with the existence of "Angelhome" in a not-so-distant future, we can take steps to solve them.

You cannot have Angelhome on a synchronous orbit around Venus, because no such orbit exists. A synchronous orbit is one that has a period equal to the average rotational period of the body being orbited and in the same direction of rotation as that body.

A Venusian siderial day (the time it takes Venus to rotate exactly 360° around its axis) is 243 Earth days long. In fact, a Venusian year (224,65 Earth days) is smaller than a Venusian day.

Math don't lie.
We can easily calculate the distance needed from the center of the planet for a synchronous orbit around Venus:

[math] R = \left(\frac{T^2GM}{4\pi^2}\right)^{1/3}[/math]
(Where R is the distance from the center of the planet, T is the orbital period, G is the gravitational constant and M is Venus' mass.)

Convert the days to seconds and plugin Venus' mass in kg. The result will be in meters from the center of the planet.

(Source for Venusian siderial day and mass, Orbiter\Config\Venus.cfg)

The result is ~7.07 billion meters or 7.07 million km. Venus' Sphere of influence extends only to about 616 thousand km, so it's impossible to place an object around Venus in an orbit with such a long period.

That said, I don't see the benefit of a synchronous orbit around Venus even if such an orbit existed. For Earth, the synchronous orbit, is the altitude we place our communications satellites because we have ground stations/antennas/dishes and it's handy to bounce a signal by always aiming at the same direction in the sky.

The hellish Venusian environment means no ground stations. No ground stations, no need for a synchronous orbit.

Now to the self-sustained part. I guess it depends on your definition of self sustained. After all, I can't think of any city on Earth that is self-sustained, why should one orbiting Venus be?

Suppose that you build the station with everything transported from Earth and you try to make it so that all the food is produced there by the farms you mentioned. What about water? metal alloys? plastics?. Even with very evolved 3D printers and a very high recycling factor, you still need the raw materials. Unfortunately those materials don't exist near Venus. The composition of the atmosphere and the surface conditions make any attempt to get at least some (metals?) directly from it extremely difficult.

The only thing that comes to mind, would be the capture of an asteroid or more and placement in a convenient orbit. Then your raw material needs could be covered.

The problem is that at that distance from the Sun, I don't expect asteroids with water ice. It would have vaporized millions of years ago.

Perhaps some NVOs (Near-Venus-Objects), -asteroids that pass regularly near Venus- and the discovery of a few very lucrative ones in terms of composition (high concetrations of platinum group metals) would make Angelhome worth the trouble of building and sustaining it.

It also means the shift of your hypothetical economy from agricultural (not much water, so not much crops) to an asteroid mining one. (Sell precious metals and other ores to get life sustaining water).

Anyway, just my :2cents:

But really, really good value for a couple of pennies, Dgatsoulis. My deepest thanks. I neither intend nor wish to abandon Angelhome despite your most excellent appraisal; there are several storylines I am constructing that use the Torus as their focus. Kylie Wilson - my protagonist - gets around. She hates it, she'd rather wrap herself up in High Heaven's comfortable city life and spend her days catching drug users and wife beaters. But she is far better than that; and must look outward to pursue her duty. The Law weakens as Humans push out from Earth. There is always a need for a Marshal - an OSD (High Heaven's Orbital Security Division) violent crime investigator to travel into the dark places of Human life and pursue murderers no matter where they might hide. And however much she hates leaving her home city, Kylie Wilson will do just that. She will chase criminals, no matter where they run. Even if they run to the darkest places of Known Space, Kylie will chase after them. She is the Bulldog, after all - and will NEVER allow criminals to relax, as long as she can hunt them down.

My intent was to find a way - using the economic and scientific focuses that can be anticipated in three hundred years' time - to make a Torus like Angelhome viable in a future economy-driven market. Obviously - by your excellent post - the Torus could not support herself with a resource-based economy. She must use something else to support herself. Unviability (is that even a word?) is NOT an option. Angelhome MUST be a self-supporting, independant colony; owing her existance to Earth but striving to free herself from Earth's Draconian restrictions. Angelhome is the Wild West of Kylie's Solar System. However impossible it might be; I MUST find a way - however weak - to integrate the Torus into the living Solar System of Kylie Wilson's world. Perhaps a world secluded - a world which studies art and science and music, cut off from the rest of the Universe - can possibly have value? To exist, Angelhome MUST have value to Humanity. If that value is not resource-based; can it be art- or science-based?
Cheers!

 

[dgatsoulis]

It can be resource based, as long as you find and capture a couple of NVOs with platinum group metals. The main problem is water.
If we can't get it whole, how about its components, hydrogen and oxygen?

Plenty of CO2 around; Feed it to the plants and get your oxygen, but hydrogen can be difficult to come by.
I read in the wiki page about the [ame="http://en.wikipedia.org/wiki/Atmosphere_of_Venus"]Atmosphere of Venus - Wikipedia, the free encyclopedia[/ame] that hydrogen ions exist in the magnetotrail of Venus, no idea about how feasable it would be to scoop it.

Here is another idea: The surface is unforgiving and there are no moons to exploit, but surprisingly, Venus has the most Earth-like place in the solar system. The cloud layer at the 50 km altitude has Earth-like pressures and temperatures, making it even more hospitable than Mars. The problem is that the top cloud layer at about ~90 km altitude has a lot of sulfuric acid, which then rains down to the surface.

So you keep the Angelhome in Low Venus Orbit and you create a floating city/research station/whatever suspended by wires hanging from baloons.

Looking around a bit, I found this:
Colonization of Venus by Geoffrey A. Landis

Abstract

Although the surface of Venus is an extremely hostile environment, at about 50 kilometers above the surface the atmosphere of Venus is the most earthlike environment (other than Earth itself) in the solar system. It is proposed here that in the near term, human exploration of Venus could take place from aerostat vehicles in the atmosphere, and that in the long term, permanent settlements could be made in the form of cities designed to float at about fifty kilometer altitude in the atmosphere of Venus.

Definitely worth a look.

 

[Staiduk]

Thanks, Dgat; a thread I can hang hopes on. I don't know if I'm right or wrong to demand realistic purposes for my fictional colonies; I only want them to be as realistic as possible. In other words - in the year 2231 is there not some way a Torus over Venus could find to be self-sustaining?

Your science and math is intriguing but I must confess I understand little of it. I'm a simple Printer with no mathematical knowledge. All I want to know is this: can Angelhome exist in the environment I've presented? Economic rules must apply, but I'm willing to give broad lisence to scientific possibilities. In short, I'm looking for excuses, not facts.

But don't disparage me for that. To date, I've been remarkably accurate in my guesses. THIS guess is different, demanding mathematical literacy; something I don't posess. All I want is to create a plausible world for my protaginist to chase down Bad Guys in.

Cheers!

 

[RGClark]

(chuckle) It does rather, doesn't it? At least it doesn't look like the Yamato - however totally and completely cool that ship was!
I love how the vast majority of this thread is way, way over my head - aside from how much I'm learning its nice I've actually been able to ask something that has interested smart people. I can't offer much about the mathematics, but can interject here since Mr. Clark got the basic outline of how I set up my future Solar System spot on.
Spaceflight in Kylie's universe is dependant upon four Habitats in sychronous orbit over their respective worlds. These space stations are huge orbiting cities; destinations for travel and tourism in and of themselves, the largest (High Heaven, orbiting Earth) more than fifteen kilometers in length with a current population of 1.2 million. Each Habitat has additional duties given their placement. High Heaven is the main fuelling, loading and servicing port for all Solar System shipping. All large ships leaving Earth make port at HH to be serviced, fuelled and loaded with cargo before heading to their destinations. As such she also is the primary center for command, control and security of all Solar System flight.
Lunar Haven orbiting the Moon is only slightly smaller at 13kms. and serves the Moon's burgeoning population.
The Moon's primary purpose is heavy manufacturing and mining - so much so that 3M moved its principle headquarters and factories there from Minnesota; keeping the trademark but changing the first word in the name. Much mining is centered around fuel production. I'm not exactly sure what fuel is produced; if it is as simple as oxy/hydrogen or something a bit more exotic. But either way, the Moon produces fuel which is sent via catapult to Lunar Haven; which sends it in huge tankers about the Solar System; most heading to High Heaven and Earth. (Side note: The Moon also sends energy directly to Earth in the form of a microwave beam; which supplies a good part of the home planet's energy needs. Politics ensues. )
So basically fuel comes in to High Heaven from the Moon via Lunar Haven, shipping comes into HH and is sent from there - well; just about anywhere they want to go.
Next in line is the smaller - but still huge at 10km. - Nouvelle Paris (pop. 350,000) over Mars; serving the Jovian system and that planet's small (100,000) but growing population. (New Paris - true to her terrestrial roots - also serves as a cultural and artistic bastion in the pragmatic, practical Outer Colonies. Food, art, theatre and beauty are highly prized. If you're smart enough to realize this opens the door to the black market and organized crime; you'll be able to understand just how dynamic and adventurous life in "The Far France" can be. )
Fourth and last is Angelhome over Venus - a much smaller 3km. Stanford Torus design. Originally a research station, now an independant - and independantly minded - community of ex-pats, researchers, adventure-seekers and artists; with a population of perhaps 80,000.
A fifth Habitat - another Torus - destined for Ganymede is currently being built in Lunar orbit and primary construction is expected to be finished within the next 30 years. Outfitting and interior construction will be completed by Martian facilities once those facilities are built and the as-yet-unnamed Torus (the working title is Clarkestowne after the ancient author that inspired so much of spaceflight) towed to Mars.
Yeah, OK - I got a little carried away but I'm having such fun with my personal Solar System. :thumbup: My goal was to design Human expansion in the most logical and realistic way possible, including the expected explosion of extra-terrestrial settlement once conditions are ripe. Thus Bob Clark's comments regarding Lunar fuel production are spot-on in terms of my solar system. Heck - we've got a great big piece of undeveloped ground just sitting there three days away - let's use the bloody thing!

Looks like a good plot outline for a near term S/F story on colonization of the Solar System. You might want to at the same try developing it into a script. There haven't been many movies made with such a theme.

Bob Clark

 

[Staiduk]

Thanks Bob but for the moment I'm having enough trouble just trying to develop a working backdrop to a murder mystery. I won't lie - I've fantasized about cool trailers and even cooler movies as Kylie struts through the Rotunda while brave Hero-music swells....

But for right now I want to get the words right. I'm a writer; not a director. My 'sucesses' - five of them - are technical works, not fiction. For now, I have to not only balance Fiction with Science Fiction, but balance Science Fiction with Police procedure and realistic law-enforcement - all built around a super-strong and -fast but emotionally vulnerable main character.

Sorry. I've fallen in love with Kylie - I will not hesitate to admit it - and will protect her from threats - criticisms included - from outside her home.

Cheers!

 

[Ripley]

Out of context, and just for curiosity, which software are you writing your story with?
Some dedicated software of sort, like CeltX?

Free CeltX desktop version:
https://www.celtx.com/desktop.html

Or maybe...pen and paper?

 

[Staiduk]

Out of context, and just for curiosity, which software are you writing your story with?
Some dedicated software of sort, like CeltX?

Free CeltX desktop version:
https://www.celtx.com/desktop.html

Or maybe...pen and paper?

Hi Ripley. For most of my writing, I've used Microsoft Word. When I tried modifying it a few months ago I wound up destroying the OS and had to rebuild. Since I'm one of those poor fools who insist on liking WinXP; I cannot get M Office back. So for the last month I've been using - and loving - Open Office.

And yes - I do use pen and paper too, when I'm at work. I can't access the Internet at work so if I come up with a particularly interesting moment or conversation I wish to write down, I'll write it out longhand and transfer it later.

Cheers!

---------- Post added 11-26-13 at 05:19 AM ---------- Previous post was 11-25-13 at 06:41 PM ----------

It can be resource based, as long as you find and capture a couple of NVOs with platinum group metals. The main problem is water.
If we can't get it whole, how about its components, hydrogen and oxygen?

Plenty of CO2 around; Feed it to the plants and get your oxygen, but hydrogen can be difficult to come by.
I read in the wiki page about the Atmosphere of Venus - Wikipedia, the free encyclopedia that hydrogen ions exist in the magnetotrail of Venus, no idea about how feasable it would be to scoop it.

Here is another idea: The surface is unforgiving and there are no moons to exploit, but surprisingly, Venus has the most Earth-like place in the solar system. The cloud layer at the 50 km altitude has Earth-like pressures and temperatures, making it even more hospitable than Mars. The problem is that the top cloud layer at about ~90 km altitude has a lot of sulfuric acid, which then rains down to the surface.

So you keep the Angelhome in Low Venus Orbit and you create a floating city/research station/whatever suspended by wires hanging from baloons.

Looking around a bit, I found this:
Colonization of Venus by Geoffrey A. Landis

Abstract


Definitely worth a look.

I hadn't properly considered Dgat's excellent points earlier; now I am doing so and I believe he has given me the answer; though I don't fully understand his reasoning yet. Also I must apologize because the link provided returned a '404' error - I couldn't access the article.

But if I understand you Dgat, Angelhome could be self sufficient if she was orbiting low in Venus's gravity; taking in the natural resources Venus produces - namely; huge amounts of CO2 and Sulphuric acid (H2SO4, if I remember correctly). Since I could not access the article, I am stymied. How will an acid and a waste gas help Angelhome's chances at viability?

To be honest its not a major point. Angelhome will exist in Kylie's time whether or not it is a practical Habitat. I was just hoping to find a way to explain it; should the need ever arise.

Cheers!

 

[dgatsoulis]

... a '404' error - I couldn't access the article.

Sorry about that. Here is the correct link. (In that page, press the download PDF button).

But if I understand you Dgat, Angelhome could be self sufficient if she was orbiting low in Venus's gravity;

Yes.

What I am looking for, is a reason to build Angelhome in the first place, and then a way to build it and make it self-sufficient.

Reason to build it: It serves as a relay point between the floating stations/refineries that have been built previously inside Venus' atmosphere and the rest of the solar system.

Those stations float (not orbit) like hot air baloons, inside Venus' atmosphere at the ~50km altitude, where the pressure is 1 atmosphere and the temperature is at the 0°-50°C range.

Breathable air (21% Oxygen, 78% Nitrogen) is a lifting gas in the atmosphere of Venus, the same way Helium is a lifting gas in the atmosphere of Earth. So you can build those floating stations inside the balloon. The benefit of having the same pressure inside and outside the balloon means that even in the case of a large tare, it would take many hours before a sufficient amount of the lifting gas (breathable air) leeks out, giving plenty of time to repair teams to fix it.
Or, you could have many smaller balloons as different sections of the same floating city, minimizing the risk of a catastrophic failure in case one balloon gets a tare. (Or several segments in one balloon, there are many ways to minimize the damage from a tare).

Each of those floating stations could have a different purpose, ie one is used to produce oxygen, using plants. There is plenty of sunlight at that altitide.
Another one could be an ore refinery, literally dropping buckets down to the surface and scooping up fresh magma from volcanos. Or work in tandem with rovers (which would look a lot more like submarines than rovers) that grab the basaltic silicates from the surface and extract the useful elements from them. (silicon, aluminum, iron, magnesium, etc)
Another station could extract hydrogen by condensing the atmospheric sulfuric acid droplets.
Oxygen from the plants, hydrogen from the sulfuric acid, (combine those two and you have water). Also nitrogen directly from the atmosphere, silicon and metals from the surface. All the raw materials you need.

So, from those floating stations (which could be seperate or be combined into one big floating city), you can get the raw materials you need for Angelhome. (Heck, Angelhome could even be that one big floating city, but an orbiting station will be necessary, so let's keep it outside the atmosphere).

Humans inside those stations: Normal environment, they work as in any lab/industrial facility on Earth. The gravity is 90% of Earth's without the need to create it artificially through spinning.
Humans working on the exterior of the stations (support crew, damage control, etc): No need for pressure suits, but the presence of the sulfuric acid is a problem. You need some kind of full body cover for protection. An acid resistant diver's suit, with an oxygen tank on the back and a helmet with communications should be more than enough.

All those floating stations ship their goods to an orbiting facility (Angelhome), which serves as a trade center and large wharehouse. From there they get sent all over the Solar system with huge freight ships.

That's the reason you need Angelhome, (those huge freight ships don't have the ability to drop inside the Venusian atmosphere) and that's how you build and sustain it. (with the raw materials provided by the floating stations/refineries/etc).

 

[RGClark]

19.53 km/s.
Remember that that's the encounter velocity, not the velocity at periapsis.
You can calculate the velocity at periapsis with:
[math] V_{pe} = \sqrt{V_{enc}^2 + V_{esc}^2} [/math]
where [math]V_{esc}[/math] is the local escape velocity, aka the escape velocity for the periapsis altitude you choose.
[math]V_{esc} = \sqrt{\frac{2GM_{planet}}{R_{planet}+alt}}[/math]

Thanks. It's the encounter velocity I wanted since I wanted to get an idea how much higher the reentry speed would be at Mars for such a high departure speed from Earth.

I think the encounter velocity, i.e., reentry speed at Mars is only in the 3 km/s second range for a Hohmann trajectory from Earth. And even that is giving NASA fits about how to accomplish soft landing of large craft, such as a manned vehicle, in such a thin atmosphere as on Mars.

I do think it is doable even for such a high reentry speed, though. What it would require is a large heat shield at extremely lightweight. At this years Mars Society convention, mathematician/engineer G.W. Johnson discussed a lightweight material he worked with years ago that might have the desired properties:

This ceramic material is quite light at .03 specific gravity. However, it is tougher than the shuttle ceramic tiles. The shuttle tiles were quite fragile and maintenance intensive. GW's tiles would cut down on this maintenance cost and would have much reduced turnaround time for a reusable launch system purpose.

Bob Clark

 

[dgatsoulis]

I do think it is doable even for such a high reentry speed, though.

I am not so sure. Let's make a simplification and look at it as a trig problem.

With a periapsis altitude of 50 km at Mars, when you are comming in with a periapsis velocity of ~ 20 km/s (Enc V. 19.53 km/s = PeV [50km] 20.157 km/s) you will spend ~1200 km inside the Martian atmosphere.


Out of atmosphere→100km→50km→100km→out of atmosphere.

With a velocity of 20 km/s, you will cover those 1200 km in 60 seconds.
In order to get captured by the martian gravity you need to lose 15.5 km/s out of those 20 km/s during those 60 seconds. That means a deceleration of 15500/60 = 258.333 m/s² ~26 g.

Of course this doesn't take into account the deceleration for each second that passed inside the atmosphere, but cutting that number in half, should give us a fairly good rough estimate.

26/2 = 13g of decelaration needed to get captured by Mars. Even if you have a shield capable of absorbing/radiating the energy, your crew won't be in a good shape after such an aerocapture maneuver.

 

[kamaz]

What I am looking for, is a reason to build Angelhome in the first place, and then a way to build it and make it self-sufficient.

The Moon!

The Moon has a lot of metals, but it lacks volatiles (if you discount ice at the bottom of polar craters, which is quite hard to get). Venusian upper atmosphere has volatiles and good living conditions but no metals.

So Venusians scoop volatiles and send them to the Moon, and the Moon sends them metals in return. Win-win.

 

[Staiduk]

Dgatsoulis; Oh; I get it now, you're talking about the 'Jovian Mines' scenario popular in near-future S-F. I hadn't thought about applying it to any world other than Jupiter but Venus would be ideal, wouldn't she? Her incredibly dense atmosphere would easily support dirigible factories; my only concern is her sulfuric acid content: Venus is easily the most hostile environment we've yet encountered. Can we build factories that could handle her incredibly corrosive atmosphere?

So if I'm following you correctly; Venus could easily become the Solar System's principle mineral/chemical mining and production source with Angelhome as the distribution center. I can - following your logic - imagine Venus to be able to produce limitless amounts of complex chemicals and refined ores. In my solar system, iron, aluminum, titanium and gold (for its conductive properties only; NOT our current fixation on its monetary value) will be in critical demand as Humanity explodes outward; building the vast Habitats to support the expansion.

I'm not sure I accept this line though:

Another one could be an ore refinery, literally dropping buckets down to the surface and scooping up fresh magma from volcanos. Or work in tandem with rovers (which would look a lot more like submarines than rovers) that grab the basaltic silicates from the surface and extract the useful elements from them. (silicon, aluminum, iron, magnesium, etc).

The rovers are fine but long-line buckets? I'm not so sure. If one is to reap resources from the hellish surface of Venus; I cannot imagine any scenario which will not require human workers to suit up and slave away in the worst place in the Solar System. That in itself offers story possibilities - can you imagine the culture that such hardy workers will develop?

Thanks so much; you've given me a lot

 

[Staiduk]

The Moon!

The Moon has a lot of metals, but it lacks volatiles (if you discount ice at the bottom of polar craters, which is quite hard to get). Venusian upper atmosphere has volatiles and good living conditions but no metals.

So Venusians scoop volatiles and send them to the Moon, and the Moon sends them metals in return. Win-win.

Does it? I'll have to look it up again, I fear I was ignorant as to the Moon's geology. I have always assumed the moon to be very metal-deficient; a rocky rather than metallic body. Iron almost nonexistant, much aluminum but not in a form easily extracted. I'll have to read up on it again. Thanks

 

[RGClark]

I am not so sure. Let's make a simplification and look at it as a trig problem.
...
With a periapsis altitude of 50 km at Mars, when you are comming in with a periapsis velocity of ~ 20 km/s (Enc V. 19.53 km/s = PeV [50km] 20.157 km/s) you will spend ~1200 km inside the Martian atmosphere.
Out of atmosphere→100km→50km→100km→out of atmosphere.
With a velocity of 20 km/s, you will cover those 1200 km in 60 seconds.
In order to get captured by the martian gravity you need to lose 15.5 km/s out of those 20 km/s during those 60 seconds. That means a deceleration of 15500/60 = 258.333 m/s² ~26 g.
Of course this doesn't take into account the deceleration for each second that passed inside the atmosphere, but cutting that number in half, should give us a fairly good rough estimate.
26/2 = 13g of decelaration needed to get captured by Mars. Even if you have a shield capable of absorbing/radiating the energy, your crew won't be in a good shape after such an aerocapture maneuver.

I'm allowing the reentry to get quite closer to the surface, skimming the tree tops so to speak. Then the reentry is much gentler, in the 6 to 7 g range. Once you've slowed down to the 15 km/s range or so, you can arrange your heat shield to use aerodynamic lift to curve the path around Mars. This would give you more time to slow down so that the time at high acceleration would be shortened. The centrifugal acceleration at 15 km/s in this case would also be in the 6 to 7 g range.

A NASA report shows astronauts reclining in acceleration seats should be able to withstand this for several minutes:

G tolerance (Dani Eder; Henry Spencer; Jordin Kare; James Oberg).
http://yarchive.net/space/science/g_tolerance.html

Bob Clark

 

[dgatsoulis]

Can we build factories that could handle her incredibly corrosive atmosphere?

Anti-corrosive materials do exist. Today we store sulfuric acid with 98% concetration in Fluoroplastics/Fluoropolymers (FEP, PFA,PTFE) containers. (source)

So it isn't a very big stretch of the imagination to have a material (2.5 centuries from today) that is light enough to make a baloon and resistant to sulfuric acid.

The rovers are fine but long-line buckets? I'm not so sure. If one is to reap resources from the hellish surface of Venus; I cannot imagine any scenario which will not require human workers to suit up and slave away in the worst place in the Solar System. That in itself offers story possibilities - can you imagine the culture that such hardy workers will develop?

I can definitely see the posibilities for story lines in such an environment, but we have look at the challenges.

A material that can withstand pressure of 90 atmospheres? No problem.
A material that can withstand temperatures of +450 C° ? No problem.
A material that can withstand corrosion from sulfuric acid? No problem.

A material that can do those 3 things at the same time? Problem.

Anyway, you have 2.5 centuries of material science ahead of you so saying that it's impossible would be a lie. IMO robots and buckets would be safer, but it's up to you to decide.
For the question of whether it would possible or not, I'd say definitely possible.

 

[kamaz]

Does it? I'll have to look it up again, I fear I was ignorant as to the Moon's geology. I have always assumed the moon to be very metal-deficient; a rocky rather than metallic body. Iron almost nonexistant, much aluminum but not in a form easily extracted. I'll have to read up on it again. Thanks

Rocks are metal (oxides)

What Moon doesn't have is concentrated metal ores (these need flowing water to be created), so you're limited to strip mining the regolith and sifting through it. On the other hand, it has an interesting type of soil named KREEP: http://www.lunarpedia.org/index.php?title=KREEP

And it even has radioactive elements if you need to power your reactors: http://the-moon.wikispaces.com/RoI+-+Compton-Belkovich+Th+Anomaly

On top of that, there were some very interesting results from the LCROSS misssion -- it appears that the permanently shadowed polar craters, in addition to water, have significant quantities of platinum-group metals (gold!): http://moonmapper.wordpress.com/2010/10/30/the-lcross-brew/

Here is a good site with info about lunar resources, compiled by a scientist who specializes in this: http://www.spudislunarresources.com/ -- look through the lectures in "Moon 101" section.

And the reference work on lunar geology, except that it is based on Apollo-era info, so it is becoming dated with new discoveries (looks like we've missed a lot of stuff the first time around): http://www.lpi.usra.edu/publications/books/lunar_sourcebook/

 

[Staiduk]

A material that can withstand pressure of 90 atmospheres? No problem.
A material that can withstand temperatures of +450 C° ? No problem.
A material that can withstand corrosion from sulfuric acid? No problem.

A material that can do those 3 things at the same time? Problem.

Beautifully explained, thanks. My thinking is based around my own real-world experience: however engineers, theoreticians and dreamers imagine a worker's job can be safer or easier due through the application of technology; the worker still has to go out and bust his backside in order to earn his paycheque. Even if we can develop plastic armour/ships/equipment, even if we can build robots to do much of the work, there will still - at least in 200 or so years; a relatively short span - be a need for tough guys and gals to go out and work the Venusian mines and suffer through too-long hours for too-small paycheques. Mmm - you've given me the idea for another subculture - thanks! :thumbup:

Rocks are metal (oxides)

What Moon doesn't have is concentrated metal ores (these need flowing water to be created), so you're limited to strip mining the regolith and sifting through it. On the other hand, it has an interesting type of soil named KREEP: http://www.lunarpedia.org/index.php?title=KREEP

And it even has radioactive elements if you need to power your reactors: http://the-moon.wikispaces.com/RoI+-+Compton-Belkovich+Th+Anomaly

On top of that, there were some very interesting results from the LCROSS misssion -- it appears that the permanently shadowed polar craters, in addition to water, have significant quantities of platinum-group metals (gold!): http://moonmapper.wordpress.com/2010/10/30/the-lcross-brew/

Here is a good site with info about lunar resources, compiled by a scientist who specializes in this: http://www.spudislunarresources.com/ -- look through the lectures in "Moon 101" section.

And the reference work on lunar geology, except that it is based on Apollo-era info, so it is becoming dated with new discoveries (looks like we've missed a lot of stuff the first time around): http://www.lpi.usra.edu/publications/books/lunar_sourcebook/

Superb info - thanks so much! :thumbup:

 

[RGClark]

Sorry about that. Here is the correct link. (In that page, press the download PDF button).

Yes.

What I am looking for, is a reason to build Angelhome in the first place, and then a way to build it and make it self-sufficient.

Reason to build it: It serves as a relay point between the floating stations/refineries that have been built previously inside Venus' atmosphere and the rest of the solar system.

Those stations float (not orbit) like hot air baloons, inside Venus' atmosphere at the ~50km altitude, where the pressure is 1 atmosphere and the temperature is at the 0°-50°C range.

Aerospace engineer Jon Goff has been writing about the Landis idea of floating stations on Venus on his blog:

http://selenianboondocks.com/2013/11/venusian-rocket-floaties/

Bob Clark