Leave Mars Alone!

[sigurdV]

No. Why? Temperature.

Why?

EDIT: I was expecting an interesting conversation with you..filled with interesting arguments and what do I get? "No. Why? Temperature."

 

I was in a hurry so I "disliked" your post and gave an equally unpolite reply. "Why?"

 

"Temperature" is what is called a "macroscopic" concept and originally all our concepts were that kind. Through the honest toil of my heroes the microscopic concepts were defined out of the macroscopic ones. So some macroscopic concepts could be redefined microscopically! Like temperature! I wont get into details invoking formulas (when not necessary) instead of using ordinary language I see unnecessary formulas as signs of weakness not as a sign of competence. Suffice it to say the "temperature" is a concequence of the random movements of molecules! So if a cloud of molecules is compressed into a bag transported through space , and the bag opens the cloud will leave the bag because it has temperature. I take your post to state that the molecules in a river of molecules flowing through space will leave the river as a consequence of the temperature of the river. Right?

 

If so you did not understand my objection which simply is that if the molecules does not move with respect to the bag they will never leave the bag! If the molecules in the river seen from the point of view of the river does not move then the river will transport all of them through space towards the destination of the river.

 

I hope you understand the difference between a Laser Beam and the light from an ordinary Flash Light?

If the molecules in a space river behaves like photons do in a Laser then they will not leave the river.

 

A laser beam IS a space river of photons... do you understand my concept now? You MAY answer with a yes or no ;)

 

PS: I dont understand why the disliking is allowed in a scientific forum, what has it to do with scientific value?

All it does is telling Trolls and Trollhunters who to harass without risk of waking up moderators.

Edited April 18, 2013 by sigurdV

[CraigD]

The only way I can imagine moving huge masses like atmospheres from orbit to orbit in the inner solar system would involve gigantic solar sails – perhaps doing double-duty as gas bags, as something would be needed to prevent the gas from diffusing into space. Pretty fun stuff, but very futuristic engineering.

Suppose the gasbag ruptures then the gas diffuses...why?

Its because the vectors are random...

Give all molecules a strong push

I think you’ve not calculated how strong a push is needed to transfer a body from Venus to Earth/Luna orbit, so don’t appreciate how large it is.

 

Per a Hohmann transfer (an easy-to-calculate maneuver that’s a good approximation of the minimum total velocity change required for any transfer, it’s about 2707 m/s (with another 2495 at Luna, which can be accomplished “for free” by a physical collision). This is not problem for various present day and imaginable near future rockets, but for something that can handle the gigantic payloads of even a small fraction of an atmosphere, and deliver much more mass of payload than they use for propellant, I can’t imagine any near-future feasible approach except a solar sail. A solar sail must be physically connected to its payload, so for a payload of gas, needs to have it in a bag.

 

in the same direction and the cloud will not diffuse.

Making my river of Venusian air to the Moon possible...

What you’re proposing requires, as Eclogite’s one-word answer hints, cooling the “river of air” to nearly 0 K. Such technology exists now – it’s how groups like CERN’s ATRAP collaboration decelerate antiparticles enough to make and store antihydrogen in magnetic traps – but it takes a lot very large and expensive equipment and energy to cool a few thousand atoms. Though efficiency’s continue to be improved, at present, such refrigeration costs on the order of US$10,000,000,000,000 (ten trillion dollars) per gram.

 

What you’re essentially proposing, Sigurd, is applying a similarly complete refrigeration process to masses on the order of 10¹⁸ grams.

 

Once you have a gas at near 0 K, each atom would need to be given precisely 2707 m/s speed in a precise direction. This is an easy matter using particle accelerators on charged particles, but for neutral ones, I can think of not technology other than ones involving containers. If containers are involved, there’s no need to go to the tremendous difficulty of cooling the gas.

 

I hope you understand the difference between a Laser Beam and the light from an ordinary Flash Light?

If the molecules in a space river behaves like photons do in a Laser then they will not leave the river.

There is a fundamental difference between a stream of photons, whether produced by a laser or other source, and a stream of gas. Photons don’t interact in one another in a way that changes their momentum. Atom do.

 

I’ve not read, or done myself, a model of a stream of gas in vacuum, so can’t even estimate how it would disperse, but from this fundamental physics fact, know that, unlike a stream of light, it must in principle disperse somewhat. Sigurd, do you have original calculations, or a reference to calculations, supporting your claim that a gas stream in space would not “leave the river”?

 

Note that, despite the inherent lack of interaction of photons, no light beam, including laser-generated, is perfectly collimated (all photons having the same direction). (source: wikipedia article collimated light)

[sigurdV]

Hi Craig!

No thats not how I think its done: I suggest electromagnetic induction of ionised molecules its not necessary to imitate a laser beam ;)And the HUGE masses may take as long time to transport away as necessary...the terraforming aspect of this im not so interested in, its the value of a continious stream that is great...when the first trickle arrives its there (and can get continiously larger) for a long time:)

That was just to show that THE PRINCIPLE WORKS, to show that rivers in space are theorethically possible. Ive been worrying for a quite a while on the scientific qualities of internet forums: It seems to me that no serious Scientific Research goes on anywhere.Its either fun & jokes or deciding how to interprete theory... to decide whether somebody is a troll or not. If you know of any Real Research done in any forum open to laymen I would like to know because Im a researcher at heart not a teacher!

 

In this thread Im investigating the hypothesis that the most economical way to transport matter in bulk through space is to send it in molecular form as a stream of matter.By an inductor...basically a simple cyclotron or in even simpler words: using an electromagnetic rail, not travelled by trains but by molecules.This "rail" need not be heavy: Balloons created out of the atmosphere of venus and just painted with iron paint might do...solar powered induction rings... is what should be used... dunno how long between them and how big they must be...that can be worked out here on earth. Say... an attemptt to transport oxygen up to the space station by electromagnetic induction.

 

REAL researching scientists would try to find the problems in the picture and SOLVE them instead of showing them to me claiming they are proof that my ideas are useless! A real researcher would not do this to anyone trying to find solutions to problems... next time, the next idea, may be a good one...he thinks! But the spirit of "Scientific" Forums is different... Im not speaking so much out of personal interest here...I manage fine thank you :)

 

But ive seen LOTS of so called TROLLS that I saw as something else: bewildered seekers of explanations to problems they have and getting punishment for trying to explain what they think they see. Being told things like: Time has no rate of change: it always passes one second per second... Ive seen it told many times to many ppl and it was a LIE every time! I think I can prove that by my clock experiment in questions and answers where the rate of change of time inside the centrifuge can be measured by a clock outside the centrifuge working together with a clock inside the centrifuge! I didnt count but i think its at least 10 educated ppl some of them moderators claiming that trolls were disrupting things in the forum by claiming time has a rate of change. Eh...Im not speaking of this forum! I think this is one of the better forums on the net. (But I think maybe there was one attempt to prove that a minute always takes one minute to pass...)

 

I think you are aware that electromagnetic induction has been thought of as means of transporting matter from the surface of the moon into space?

So IF a passenger cabin with passengers can be lifted out into space THEN why not a continious flow of ionised molecules? they will all travel with approximately the same speed and direction and there can be induction rings in space to keep the stream intact and to speed the stream up... And it can ALL be driven by solar power! Its free except for inititial costs! How can Sails and Bags be cheaper?

 

I would like a careful analysis of WHY gas accelerated enough by electromagnetic induction to leave a large object like the moon, or venus high atmosphere, gets diffused in space...most of the molecules should have no momentum other that in the direction of travel surely? Of course some molecules will be lost... technical solutions do not in general work with a 100% efficiency.

you see I dont understand that and If its true then maybe Ill find a solution...thats how my mind works!

 

PS: Neutral molecules of different kind can be joined to form an ionised molecule.

I’ve not read, or done myself, a model of a stream of gas in vacuum, so can’t even estimate how it would disperse, but from this fundamental physics fact, know that, unlike a stream of light, it must in principle disperse somewhat. Sigurd, do you have original calculations, or a reference to calculations, supporting your claim that a gas stream in space would not “leave the river”?

No I havent...The Idea has NOT been discussed anywhere that I know of! Sorry! Its all in my mind :(

As I said: if my thoughts doesnt seem new and UNTHOUGHT of I usually dont print them. (Its interesting to note that most forums demand thoughts to conform... to be thought of before... moderators want to be able to find the thought somewhere... Is this the Scientific Spirit? Will it not instead guarantee that NO new thoughts will get printed within the forum? Please argue that forums has Scientifical Value and lots of brilliant research... Or at least education gets done!

And I do agree that some molecules will be lost, but I guess there will be natural transport routes where inductors combined with solar power collectors strategically placed could prevent losses from being high. When they get many the route could perhaps be used for passenger transports as well.

Edited April 22, 2013 by sigurdV

[Eclogite]

REAL researching scientists would try to find the problems in the picture and SOLVE them instead of showing them to me claiming they are proof that my ideas are useless! A real researcher would not do this to anyone trying to find solutions to problems... next time, the next idea, may be a good one...he thinks!

I am not a real researcher. I have never made any claim, implicit or explicit, to be one. If an idea appears to be, to the extent of my knowledge, useless, then it would be improper, unscientific and deceitful for me to pretend that it was not. Trying to solve the problem with the idea when the idea is wrong would be a way of pretending the idea was not wrong.

 

Your idea for imparting a velocity to a cloud of gas and directing to wherever would not work for the simple reason i gave you: temperature. I did not think I would need to explain any more than that to someone who asserts that they have some knowledge of science. Craig has expanded on why your idea won't work. It would encourage me to engage in "an interesting conversation with you", if you were to acknowledge that the idea is a non-starter. If not, then provide some kind of solid science to suggest why it could work. Appeals to flawed analogies with light will not do.

[sigurdV]

 

 

Your idea for imparting a velocity to a cloud of gas and directing to wherever

 

In this thread Im investigating the hypothesis that the most economical way to transport matter in bulk through space is to send it in molecular form as a stream of matter. Temperature makes it difficult to send molecules into space from the surface of the moon you say?

[Moontanman]

In this thread Im investigating the hypothesis that the most economical way to transport matter in bulk through space is to send it in molecular form as a stream of matter. Temperature makes it difficult to send molecules into space from the surface of the moon you say?

 

 

Sending a gas anywhere in space without it being contained by a solid is impractical if not absolutely impossible...

[sigurdV]

Sending a gas anywhere in space without it being contained by a solid is impractical if not absolutely impossible...

I note that everybody believes it to be so but nobody proves it to be.

It must be nice to believe without any proof...Next stop the Church?

Heres a couple of first questions:

 

Using one induction site at a Moon base

1 Can uncontained ionised molecules be sent into orbit?

2 How many molecules can be sent per second?

3 For how long can the molecules be kept in orbit?

4 For eventual use by a close by space factory or space station?

5 Supposing the system runs on solar power: what is the cost?

6 What are the costs for competing systems?

 

The term "gas" does NOT come from me:

its been forced on me from opponents.

Im talking space resources like the Atmosphere of Venus,

the Minerals of the Moon and Solar Power.

[moonguy]

Too bad this thread has been inactive for so long. It was just starting to get interesting.

I'm new here, but I have to tell you, if you have any notion of significantly colonizing Mars, you will not be able to do it economically from here. ('here' = Earth/Moon) You will have to do it from - believe it or not - Mercury. I know, I know, I know... Mercury gets REALLY hot; the delta-V's are pretty stiff most of the time. Still. . .

Mercury and Mars have a 101-day synodic period. Earth and Mars have a 780-day period. That means for a given transport technology you will have seven times as many launch opportunities to Mars from Mercury than from Earth. Seven times. If your Mars colony ultimately weighs 1000 tons, and you want it done in a decade, you can send it from Mercury in 32.5 ton payloads every 101 days. To do that from Earth would require launching 250 tons of payload in each of the four Earth-Mars launch opportunities. Interesting, don't you think?

Of course, as you probably have guessed, there's more. . .

[CraigD]

Welcome to hypography, moonguy! You sound like a spaceflight fan - please feel free to start a thread in the introductions forum telling us about yourself.

 

... if you have any notion of significantly colonizing Mars, you will not be able to do it economically from here. ('here' = Earth/Moon) You will have to do it from - believe it or not - Mercury.

I'd have to see more than a "believe it or not" to accept this idea, for several reasons.

 

... the delta-V's are pretty stiff most of the time.

As with all nearly circular starting and ending orbits, the delta-Vs for a transfer orbit from Mercury to Mars are pretty stiff all of the time!

 

Let's look at the actual numbers, using the easy-to-calculate Hohmann transfer orbit

For Earth Solar orbit to Mars Solar orbit transfer, the 2 are about 2945 and 2649 m/s

For Mercury orbit to Mars orbit, they're about 12584 and 8770.

 

12584 m/s is a lot of delta-V, more than Earth's escape velocity of about 11200. Intuitively, then, transferring from Mercury's orbit to Mars's takes a bit more delta-V than escaping Earth's surface, so crashing payloads into Mars from Mercury's orbit can be expected to be economically similar to doing it from Earth to Luna (A Saturn V stack to deliver an Apollo CSV and LEM). To orbit or land them softly, you need the 2nd, 8770 m/s delta-V maneuver, making such a mission economically similar to sending a Saturn V stack to Luna - assuming no changes due to scaling, an increase in mass of about 60 times, so an increase in cost of about the same.

 

Mercury and Mars have a 101-day synodic period. Earth and Mars have a 780-day period. That means for a given transport technology you will have seven times as many launch opportunities to Mars from Mercury than from Earth.

True, but when planning the trips of many spacecraft that can stay in space for long time, how often launch windows occurs isn't as critical as usual, because you can launch each of your many spacecraft as quickly as your launch facilities allow, parking them in orbit until the moment their transfer orbits should be started, then start them all at the same time. This is a different mode of planning than the usual, where if a planned launch window is missed, having the the spacecraft ready for the next minimum-cost window is costly, analogous to many large naval ships visiting a port that can only accommodate one or a few of them at a time, forming a fleet near shore, then traveling together to their destination.

 

The big problem with colonizing Mars from Mercury, or anywhere other than Earth, is that everything needed - people, spacecraft factories, etc - is on Earth, not on Mercury. So to colonize Mars from Mercury, you must first colonize Mercury from Earth. The delta-V for a Earth-to-Mercury Hohmann transfer is about 7533 and 9612 m/s, about 3 times that of Earth to Mars when escaping Earth is ignored, 1.7 times when it's not.

 

If you're going to have a non-Earth base/colony on something massive as the launching point to colonize Mars, the obvious choice is Luna, as it's the easiest to reach from Earth, and has a pretty low escape speed (2400 m/s, compared to Mercury's 4300 and Earth's 11200). This is a popular enough approach that even politicians occasionally propose it.

 

If I was going to pick another, despite the energy issues I've outlined above, Mercury (or an even closer solar orbit shared by no planet) would be high on my list, as would be Jupiter. The reason for both is availability of energy for manufacturing. However, successfully colonizing either Mercury (or sunward) or Jupiter appears to me to be more difficult than Colonizing Mars, so the only in-between that make sense to me is either nothing - various near-Earth orbits, including the Lagrange points - or Luna.

 

Of course, as you probably have guessed, there's more. . .

Do say... :)

[moonguy]

Thanks for the great response, CraigD! And yes, there is more. . .

Our concern about delta-V, which you very accurately portrayed, has to do with our use of liquid propellants. In the context of colonizing Mercury, we have a proven alternative: photon drive, more commonly known as solar sails. Robert Forward, Jerome Wright and others have outlined the capabilities of solar sails years ago. In the case of Mercury, as an example, it is possible to deliver a 185-ton payload to Mercury orbit from Earth in a flight lasting about 2.13 years - half the time it took MESSENGER to arrive. In theory, Earth could send such payloads towards Mercury three times a year (Earth-Mercury synodic period being 115.9 days) with subsequent arrivals at the same intervals 2.13 years later. Smaller payloads would arrive much faster. That tonnage is not bound for Mars. It is mining, mineral processing and fabrication equipment to be used on Mercury. This equipment uses the solar energy (electrical and thermal) to produce the construction materials which are sent to Mars. Solar sails leaving Mercury have six to ten times the solar flux to work with and can push greater payloads outward than Earth could send inwards. . .

 

Delta-V for manned flights start around 6.1 km/sec. for the transfer orbit velocity. Mercury Orbit Insertion can be another 6.1 km/sec. or more. Return flights would be the same delta-V, so it would be ruinously expensive if all the propellant had to be brought from Earth for the round trip. Fortunately, MESSENGER has confirmed laarge quantities of water-ice on Mercury as well as some form of as yet undetermined hydrocarbon.

 

It is true that a program of planetary exploration does not really have a problem with launch window frequency. A program of major construction of colonies would need regular arrivals of materials. Mercury's more frequent launch opportunities facilitates that.

 

The Moon suffers from the same limitation as Earth where window frequency is concerned. People, however, represent only a small fraction of the total mass of a colony. It is reasonable to send people from Earth to colonize Mars. Sending people to Mercury is also reasonable because the actual propellant masses required are not as far apart as the delta-V's. This is because the manned Mercury vehicle's payload is smaller for a given crew size than one going to Mars. Typically, flights to Mercury average about 45% as long as flights to Mars. With current technology, the shortest flights to Mercury would be about 85 days while the shortest to Mars are about 170 days.

 

Needless to say, I'm into this topic. I'm seriously considering a new thread for it. . . Thoughts?

[CraigD]

Our concern about delta-V, which you very accurately portrayed, has to do with our use of liquid propellants. In the context of colonizing Mercury, we have a proven alternative: photon drive, more commonly known as solar sails.

Light sails, or more generally, “sail craft” pushed by anything, are IMHO the best way to propel a spacecraft, if you can get such systems to work. Getting a lightsail craft to work is harder than some would have us believe.

 

Though simple in principle, I wouldn’t describe solar sails as “proven” technology – of the 4 solar sail craft launched to date, only 1, JAXA’s beautiful 200 m², 315 kg IKAROS 2010, is the only to succeed. Deploying and handling super-thin sails, while simple in principle, isn’t easy in practice.

 

Our concern about delta-V, which you very accurately portrayed, has to do with our use of liquid propellants.

Changing trajectories in space doesn’t depend on the source of the acceleration causing the change, although obviously the magnitude and duration of the acceleration does.

 

Hohmann transfer calculations are useful for finding minimum required velocity changes (delta-Vs). These delta-Vs are accurate only for spacecraft with motors (I’m using “motor” in the most generic sense of “that which produces acceleration”) that can produce high force (and thus, high acceleration) for short periods, which include present-day chemical rocket motors.

 

For motors that produce low thrust for long periods, such as light sails, the delta-V is the difference between the starting and ending orbit speed, which is always greater than for a Hohmann transfer. This makes it easy to calculate, for a given continuous acceleration, the transfer time, though difficult to calculate the precise trajectory, or the transfer time if the acceleration varies, as is the case with a solar sail. The only way I know to do it is via simulation, and I’ve yet to actually run one, or found a description of a run of one online.

 

Robert Forward, Jerome Wright and others have outlined the capabilities of solar sails years ago.

I’ve been a Robert Forward fan dating back decades, to when he was still alive, especially of his light sail propulsion ideas. I'm a big fan.

 

This is the first I’ve heard of Jerome L (Jerry) Wright, though I see he wrote Space Sailing in 1992, and seems to have been active in updating the wikipedia article Solar Sail since 2007. Alas, I can’t find an electronic copy of the book, only this website, which has some general information of solar sails and some sample conclusions, but no useful details on how to calculate the very-low acceleration orbital maneuvers needed to reach such conclusions – in short, doesn’t “show his work”.

 

There’s something a bit sketchy about Jerry Wright. On the back cover of Space Sailing, he’s described as the CEO of a company, “General Astronautics”, which appears to have no public identity beyond this website. A search on the General Astronautics and Jerome L Wright finds a couple of addresses in Washington USA, and British Columbia CA, and a 1998 order blocking him or Bruce Dunn from trading securities (that is, getting money from investors) in BC.

 

Several source, including this one from Louis Friedman’s 1988 The History of Solar Sailing mention Wright as having played a key role in JPL’s 1970s work, which was lead by Friedman, to use a solar sailcraft to rendezvous with Halley’s comet around 1986 – work that NASA canceled, other than very small funding for continued design studies, over the objections of Freidman, Wright, and the various other engineers and scientists working on it.

 

My impression, mostly from Wright’s introduction here, and short descriptions of his later work, such as here, is that he stayed bitter about NASA’s failure to fly his 1970s designs, and has been trying to get them flown via private ventures since then. Though I wish him and others like him luck in this noble work, I don’t think his chances of success are very good – succeeding in the private spaceflight business – unless you already have huge cash reserves and eager investors from previous successful businesses, like PayPal/Tesla Motors/SpaceX’s Elon Musk, seems nearly impossible.

 

In the case of Mercury, as an example, it is possible to deliver a 185-ton payload to Mercury orbit from Earth in a flight lasting about 2.13 years - half the time it took MESSENGER to arrive.

But the sails for such payloads must be huge!

 

Ignoring vectoring issues (unlike rockets, solar sails don’t thrust exactly in the direction they’re oriented, but in a direction calculated from their direction and the direction to the Sun), and assuming a 1 AU solar flux, and massless solar sail material (incorrectly assumptions, but OK for fists approximation) this trip, which requires a total delta-V of Speed_Mercury-Speed_Earth=~ 18,087 m/s, would require a sail with area

18087.4 m/s / (2.13 * 365.25 * 86400 s * 0.000009079 N/m² =~ 5483101 m²

which equates to a square sail 2342 m wide.

 

Using realistic sail material densities (0.007 kg/m²) increases the area requirement by about 20%. A simplistic adjustment for the increase in solar flux as we approach Mercury reduces it by about 67%. I’m at a loss to calculate the approximate sail thrust vectoring effects (here’s where I could stand some help, and wish Wright or someone has put some on his website!) but would guess at more than +50%, leaving a bottom line about the same as the first approximation.

 

Keep in mind that the largest solar sails flown to date - successful and not - are 20 m on a side.

 

These approximations give me some sympathy for the NASA administrators who were skeptical that Friedman, Wright, and team could successfully fly something this size – which around what they were proposing – within the 5 years they had to meet their Halley’s Comet rendezvous launch window.

 

In theory, Earth could send such payloads towards Mercury three times a year (Earth-Mercury synodic period being 115.9 days) with subsequent arrivals at the same intervals 2.13 years later. Smaller payloads would arrive much faster. That tonnage is not bound for Mars. It is mining, mineral processing and fabrication equipment to be used on Mercury.

The acceleration of gravity on the surface of Mercury is about 3.8 m/s/s. The acceleration of the solar sail I described above is .000269 m/s/s. So even if you could manage a sail near even a nearly atmosphere-less planet like Mercury, you’d need one unfeasibly large and light to use as a lifter.

 

So you’ve either got to make and launch rockets, make and use some sort of gun, or make and use some sort of space elevator, to get materials off of Mercury. All of these are much larger, longer, and costlier projects than I can see being offset by having more frequent lowest Delta-V launch windows.

 

Solar sails leaving Mercury have six to ten times the solar flux to work with and can push greater payloads outward than Earth could send inwards. . .

The solar flux is exactly [imath]\frac{k}{r^2}[/imath], so the solar flux at Mercury’s distance from the Sun, about 0.387 AU, is about [imath]\frac{1}{0.387^2} \dot= 6.67[/imath] times what it is at Earth’s distance. At Mars’s 1.523 AU, it’s about 0.44 times.

 

It is true that a program of planetary exploration does not really have a problem with launch window frequency. A program of major construction of colonies would need regular arrivals of materials. Mercury's more frequent launch opportunities facilitates that.

I meant the opposite of this.

 

Scientific missions are tightly governed by launch windows, because if you miss one, you have to spend a lot of money keeping your spacecraft and support systems ready for the next.

 

A major space construction program would have many launches, and could use the “parking in orbit” scheme I described previously to launch from Earth anytime, so infrequent launch windows aren’t a problem.

 

Needless to say, I'm into this topic. I'm seriously considering a new thread for it. . . Thoughts?

If you’ve no objections, I’ll move all of the Earth->Mercury->Mars posts to a new thread, because they don’t have much to do with the original “leave Mars alone” topic.

[moonguy]

You raise a lot of good issues here and they deserver a good response. Since it is inappropriate to hijack this thread (for which I apologize) I will start a new one specific to this topic. So I ask that you hold off adding Mercury colonization to another thread. . .