The asteroid mission

[HopDavid]

There is a very nice possible Earth-Venus cycler system. But at this time we know very little about asteroids with aphelions of 1 A.U. or less. Such asteroids are hard to see for a number of reasons.

What good would that be? Venus surface missions would be impossible, at best!

There are altitudes in Venus' atmosphere where pressure and temperature are hospitable to humans. At these locations, our atmosphere is a lifting gas. So balloon cities are a possibility.

Using aerobraking and the Oberth effect it is possible to capture near Venus asteroids to Venus orbit. This would make them easier to exploit in a number of ways.

Far fetched, yes. But then so is Mars colonization.

A Mars-Earth cycler would enter a very elliptical orbit, Tugs in orbit to transfer Modules to or from, low Mars or Earth orbit.

I just invested some time and effort talking about cyclers. But I see no evidence you understood a word.

Asteroids would be a piece of cake. At least two vehicles have landed on asteroids and survived.

Manned missions are more difficult than robotic. Converting asteroid resources to usable infrastructure more difficult still. Nudging said infra structure into a usable cycler orbit and maintaining the orbit? No, not a piece of cake.

 

[Yuri_Armstrong]

In many ways, I think you'll find Venus the most hospitable place for humans outside of Earth. It will require some creative thinking and mission planning to be successful though.

 

[EarthlingX]

http://www.nasa.gov : Exploration of Near Earth Objects (NEO) Objectives Workshop [Explore NOW]

August 10-11, 2010
Washington, DC

NASA is hosting an interactive, two-day workshop to identify objectives for exploration missions to Near Earth Objects (NEOs). The meeting will be conducted August 10-11 at The Mayflower Renaissance Hotel in Washington, D.C.

Using ISS parts for NEO visiting spacecraft :

Innovative Concepts for NEO Exploration (pdf)

by Brian Wilcox
10 August 2010

http://www.planetary.org : Report from the Exploration of Near-Earth Objects Objectives Workshop

Aug. 10, 2010 | 13:14 PDT | 20:14 UTC

by Bruce Betts

This week, Jennifer Vaughn and I are representing the Planetary Society at NASA's Exploration of Near-Earth Objects (NEO) Objectives Workshop, or ExploreNOW. The meeting is being held in Washington DC. Roughly a couple hundred people from a wide range of backgrounds have been brought together at this invitation-only 2-day meeting. We are discussing the exploration of near Earth objects and asteroids, particularly future human missions to NEOs.

So, why go to an asteroid with humans? Former astronaut and asteroid planetary scientist Tom Jones, a member of the Planetary Society's Advisory Council, gave an excellent overview of the arguments, which he broke down into 5 things:

1. accessibility – NEOs actually require less propulsion to get to than the surface of the Moon;
2. science of our origins – asteroids preserve evidence of early solar system formation;
3. human survival – these are the same objects that can impact Earth and cause widespread destruction, and human missions would provide information, such as physical properties, about the visited asteroids that would help us better understand how to deflect them;
4. resources for exploration – asteroids contain materials, including some fraction of water, that could be used for further exploration; and
5. stepping stones to Mars – various aspects of operations and technology can be developed and used for NEO missions that will apply to missions to Mars.

 

[samkent]

In many ways, I think you'll find Venus the most hospitable place for humans outside of Earth.

You don’t find 860 degrees and 1350 psi a problem? You do know that probe survival time has been measured in minutes instead of years?

As to the Mars/Earth cycler , are you aware that it takes just as much energy to catch up with the cycler as it does to go to Mars?

 

[scottb50]

As to the Mars/Earth cycler , are you aware that it takes just as much energy to catch up with the cycler as it does to go to Mars?

Cycler doesn't have to mean a flyby at each end. I was thinking more of a highly elliptic orbit, which would use minimum propellant use. Payloads go down and returning payloads go up. Once transfers are made the cycler would wait for the optimum orbital point to depart. Ideally a cycler could make multiple trips, with refitting and supply in Earth orbit.

Moon-Earth, Earth-Mars and asteroid or even Comet missions could be done with the same stuff.

 

[Yuri_Armstrong]

In many ways, I think you'll find Venus the most hospitable place for humans outside of Earth.

You don’t find 860 degrees and 1350 psi a problem? You do know that probe survival time has been measured in minutes instead of years?

As to the Mars/Earth cycler , are you aware that it takes just as much energy to catch up with the cycler as it does to go to Mars?

You're thinking about it too narrowly. Outposts suspended by balloons at the right altitude will give the crew:

-comfortable temperature
-normal pressure
-.90 G, a little bit less than Earth's but probably not enough to cause significant health effects

The only thing toxic would be the gases. That's what I meant by "hospitable", if done right the colonists would rather like it there.

 

[HopDavid]

As to the Mars/Earth cycler , are you aware that it takes just as much energy to catch up with the cycler as it does to go to Mars?

False.

Having adequate volume, radiation shielding, etc. makes a cycler quite massive.

The taxis that ferry passengers between planets and cycler can be much less massive. So, while their delta V is comparable, the energy is much less.

 

[HopDavid]

In many ways, I think you'll find Venus the most hospitable place for humans outside of Earth.

You don’t find 860 degrees and 1350 psi a problem? You do know that probe survival time has been measured in minutes instead of years?

Did you know there are altitudes in Venus' atmosphere where pressure and temperature are hospitable to humans? Did you know that at these locations, our atmosphere is a lifting gas? So balloon cities are a possibility.

I had just written this. I recommend you do less writing and more reading.

 

[HopDavid]

Cycler doesn't have to mean a flyby at each end. I was thinking more of a highly elliptic orbit,

You're thinking of a regular Hohmann orbit about the sun but highly elliptic parking orbits about the earth and Mars?

The high perigee velocity of a highly elliptic orbit would do you no good if the perigee isn't at the correct position when a launch window comes along.

Cyclers, in the traditional sense of the word, make flybys without stopping to park in planetary orbits. Smaller craft, known as taxis, ferry passengers between the planetary surface and the cyclers.

 

[samkent]

Have you ever heard of a balloon that didn’t leak or even pop?

What is the benefit of a balloon city over an orbital station?

Back to the cycler.
Assume you have an asteroid that has an orbit that passes Earth and then Mars. It’s not going to stop and wait for you to make a landing. To land on this asteroid you must first leave Earth orbit and match the asteroids speed and trajectory. Once you are on course for the asteroid you will also be on course for Mars.

The only benefit I can see to an asteroid ride is the slight gravity it would provide. But the likely rotation of it would cause communications problems that would offset the gravity benefits.

 

[HopDavid]

Have you ever heard of a balloon that didn’t leak or even pop?

You seem to be assuming balloon interior pressure is greater than surrounding atmosphere pressure.

I suggest Googling the topic.

What is the benefit of a balloon city over an orbital station?

There's access to resources in Venus' atmosphere, including sulfur, carbon and oxygen. And, as I've mentioned several times, an altitude with comfortable pressure and temperature.

Back to the cycler.
Assume you have an asteroid that has an orbit that passes Earth and then Mars. It’s not going to stop and wait for you to make a landing. To land on this asteroid you must first leave Earth orbit and match the asteroids speed and trajectory.

Here you are stating the obvious.

You are also missing the obvious.

The taxi must match the asteroid's speed and trajectory as you say. But the taxi need only protect and support passengers for days or weeks. The substantial mass needed to protect and support passengers for a 7 month trip is not needed on the taxi.

To get off earth's surface and achieve trans Mars insertion is about 14 km/sec. 14 km/sec for a tiny taxi requires a miniscule fraction of the energy it would take to impart 14 km/sec to an adequate trans Mars vehicle.

 

[Yuri_Armstrong]

Have you ever heard of a balloon that didn’t leak or even pop?

Somehow, I doubt that the engineers will build balloons that are supposed to float in Venus... where the pressure of Venus will crush them. :roll:

What is the benefit of a balloon city over an orbital station?

An orbital station faces the constant threats of cosmic radiation and micro-meteorites or space debris. It also has to have all of its resources imported from somewhere else to sustain itself. The conditions in the upper atmosphere of Venus are a lot more hospitable to humans than the conditions of outer space. A crew on an orbital station also has to deal with zero-g health effects.

 

[scottb50]

A crew on an orbital station also has to deal with zero-g health effects.

And then what do you do? Go around and around and send down probes to get samples? That sounds like a robot World to me, and that might be a good thing. A balloon, at low levels might not be a good idea though.

Mars, the moon and asteroids and Comets have been visited and no compelling reason say's a manned mission to any of these locations could not be done, right now, or at least ten years from now. A balloon might be good for a big facility, but the smaller and compartmentalized the better. A failure of a Module, collision, damage or other cause, could be isolated to specific Modules, a balloon wouldn't be as good.

A balloon would be heavier, though compacted balloons might be cheaper because more can be shipped.

Crews in orbital stations would be rotated regularly, some could bring their families and stay for as long as they safely can, when and if that is established. Longer missions would require longer time in Space, obviously.

 

[neilsox]

Balloons typically have at least 0.1% more pressure inside than outside, so they can pop. In theory the balloon can have rigid walls with partial vacuum inside = sort of like a submarine, which can implode. Early balloons for Venus will likely fly where the air pressure is about the same as Earth a mile or two above sea level as that is the altitude of lowest air temperature. This is above most of the cloud tops, so solar energy will be available about 1/3 of the time. Some air cooling will likely be needed to keep the crew areas cooler than 30 degrees c = 86 degrees f. Escape pods are needed in case of loss of boyancy. The pod can travel to another balloon habitat, but likely not to a station in low Venus orbit. Neil

 

[JonClarke]

To get off earth's surface and achieve trans Mars insertion is about 14 km/sec. 14 km/sec for a tiny taxi requires a miniscule fraction of the energy it would take to impart 14 km/sec to an adequate trans Mars vehicle.

It will actually need somewhat more than 14 kms to match the cycler orbit. This adds significantly to ferry mass.

And how do you know the ferry is tiny? Have you crunched the numbers?

Keep in mind that you need multiple cyclers, all quite massive.

Other factors that need clarification include:

Launch window duration to rendezvous with a cycler on a flyby trajectory (is it minutes, hours, days?)

Backup plans in the event of a docking failure in deep space. You want to avoid dock or die scenarios.

 

[HopDavid]

Balloons typically have at least 0.1% more pressure inside than outside, so they can pop.

From Wikipedia's article:

"He has proposed aerostat habitats followed by floating cities, based on the concept that breathable air (21:79 Oxygen-Nitrogen mixture) is a lifting gas in the dense Venusian atmosphere, with over 60% of the lifting power that helium has on Earth.[2] In effect, a balloon full of human-breathable air would sustain itself and extra weight (such as a colony) in midair. At an altitude of 50 km above Venusian surface, the environment is the most Earth-like in the solar system - a pressure of approximately 1 bar and temperatures in the 0°C-50°C range. Because there is not a significant pressure difference between the inside and the outside of the breathable-air balloon, any rips or tears would cause gases to diffuse at normal atmospheric mixing rates, giving time to repair any such damages. In addition, humans would not require pressurized suits when outside, merely air to breathe and a protection from the acidic rain. Alternatively, two-part domes could contain a lifting gas like hydrogen or helium (extractable from the atmosphere) to allow a higher mass density.[3]"

I bolded the part about rips and tears

 

[HopDavid]

It will actually need somewhat more than 14 kms to match the cycler orbit. This adds significantly to ferry mass.

Very true of the Aldrin Cycler. Only somewhat true of the Niehoff Cyclers, their orbits are closer to Hohmann.

Here is a nice PDF on possible Mars cyclers: Analysis of a Broad Class of Earth-Mars Cycler Trajectories

With Venus, the cycler orbits can be very Hohmann like.

In Cycler literature, the word used for ferries is usually "taxi". That's the word I try to use.

And how do you know the ferry is tiny? Have you crunched the numbers?

I would expect the minimum cycler mass to be at least that of Zubrin's Mars Transfer Vehicles which is around 40 tonnes.

The trip times and delta V requirements of a taxi are in the same neighborhood as Apollo's CSM, which was about 30 tonnes.

However, a reusable Mars transfer vehicle can be improved over time (unlike one-time-use disposable Mars Transfer Vehicles). So over time, I would expect a cycler to become more spacious and safer than Zubrin's minimal vehicles. A cycler eventually weighing 80 tonnes is plausible.

Returning the discussion closer to the thread topic, if the cycler is a nudged asteroid, it could weigh 80 tonnes from the outset. Over time living space could grow as in situ resources are more fully utilized.

 

[scottb50]

It will actually need somewhat more than 14 kms to match the cycler orbit. This adds significantly to ferry mass.

Depending on it's orbit. In an elliptical orbit it can take a lot less.

And how do you know the ferry is tiny? Have you crunched the numbers?

Keep in mind that you need multiple cyclers, all quite massive.
The cycler could be nothing more then the command center, I'm sure once it comes back from Mars it will need refurbishing, so maybe massive could translate to many.

Other factors that need clarification include:

Launch window duration to rendezvous with a cycler on a flyby trajectory (is it minutes, hours, days?)

If the inbound vehicle brakes into an elliptical orbit the window expands considerably.

Backup plans in the event of a docking failure in deep space. You want to avoid dock or die scenarios.

Obviously, but with multiple ways to do it it's not a show stopper.

 

[Yuri_Armstrong]

I have made this statement several times in several threads. Planning a manned mission to an asteroid ahead of a return to the moon or even the mission to Mars is an exercise in futility. Currently there is no valid need to send a manned mission to any asteroid. Robots can do it cheaper and better. The only reason for a manned mission to the Moon or Mars is eventual colonization and we ain't gonna put a colony on an asteroid. On the other hand we can establish a viable colony on the moon within a decade and on Mars within 50 years if we don't let stupid politicians get in the way.

Ignoring the many merits of an asteroid landing, I take issue with the bolded section. Sure, they can do it cheaper, but better??? I don't think so... a manned mission can bring more instruments and technology, and also more samples back. Humans are infinitely more nuanced that any robot. We could do a lot of science work on an asteroid by sending a manned mission. I bet a prospector or two would be interested in the potential of mining an asteroid as well, John S. Lewis puts an asteroid at $20 trillion in precious metals with a diameter of 1 mile.

The moon and Mars are great targets to shoot for, but asteroids are fairly useful as well, though colonization of them isn't as good as it would be on the moon or Mars.

 

[neutrino78x]

While I would generally say that for science, send robots, I think the case of an asteroid is different. We have a national security interest in asteroids. So if one is coming, you might want to send humans, for adaptability. It would also eliminate any delay in sending commands to a robot due to the speed of light. If all you want to do is gain observational data, as opposed to trying out various techniques of controlling it, then yes, robots would be fine.

--Brian

 

[DarkenedOne]

I have made this statement several times in several threads. Planning a manned mission to an asteroid ahead of a return to the moon or even the mission to Mars is an exercise in futility. Currently there is no valid need to send a manned mission to any asteroid. Robots can do it cheaper and better. The only reason for a manned mission to the Moon or Mars is eventual colonization and we ain't gonna put a colony on an asteroid. On the other hand we can establish a viable colony on the moon within a decade and on Mars within 50 years if we don't let stupid politicians get in the way.

Ignoring the many merits of an asteroid landing, I take issue with the bolded section. Sure, they can do it cheaper, but better??? I don't think so... a manned mission can bring more instruments and technology, and also more samples back. Humans are infinitely more nuanced that any robot. We could do a lot of science work on an asteroid by sending a manned mission. I bet a prospector or two would be interested in the potential of mining an asteroid as well, John S. Lewis puts an asteroid at $20 trillion in precious metals with a diameter of 1 mile.

The moon and Mars are great targets to shoot for, but asteroids are fairly useful as well, though colonization of them isn't as good as it would be on the moon or Mars.

Question is why is colonization of asteroids not as good as colonization of a planet. With colonization of an asteroid you have far better access to space.

 

[MeteorWayne]

But you have no gravity, certainly no atmosphere, and what is the point of access to space for a colony?

 

[Yuri_Armstrong]

But you have no gravity, certainly no atmosphere, and what is the point of access to space for a colony?

Not necessarily a colony, but a government base could "ride" an asteroid on its orbital path to launch missions to other bodies in the solar system. With little gravity and closer approach, if they select asteroids with good orbital paths, future missions would have an easier time rather than launching from Earth.

I don't really imagine there will be a colony for average people or tourists on an asteroid because there wouldn't be much point for them to go there rather than the moon or Mars. But companies, governments, and scientists could all gain a lot from asteroids.

 

[SteveCNC]

You know I've been thinking about what the president might be thinking reguarding this asteroid mission and I came to a possibility . Perhaps this isn't really an asteroid mission at all but a race to the moon with China without saying so . Think about it , what needs developing to go to an asteroid or the moon ?? heavy lift . You need to develope the ability to return from said location in either case also . There's already talk about using modules on the moon to form a base so it all fits including the possible lies about the real destination . After all we don't want to start another race do we ? or do we :roll:

 

[Yuri_Armstrong]

You know I've been thinking about what the president might be thinking reguarding this asteroid mission and I came to a possibility . Perhaps this isn't really an asteroid mission at all but a race to the moon with China without saying so . Think about it , what needs developing to go to an asteroid or the moon ?? heavy lift . You need to develope the ability to return from said location in either case also . There's already talk about using modules on the moon to form a base so it all fits including the possible lies about the real destination . After all we don't want to start another race do we ? or do we :roll:

Another space race with a country like China would be great. We would see a lot more scientific and technological advancements, and math/science oriented education like in the 60's and early 70's. China is already setting up their first space station after all, and I don't think it will be too long before they leave LEO.

I'm not sure what lies you're talking about, ideas for a multi-module moon base have been around for decades.