Compressed gas balloon rocket for Mars launch

GW Johnson · 2020-06-17 16:26:45

Well, remember, the baseline design job of Starship/Superheavy is as a fully reusable freighter to LEO. That's where they started, and with some extras, you can do those other jobs.

Point-to-point on Earth requires Superheavy, but can carry larger payload, as it need only attain high suborbital speed. Say 6.5-7 km/s instead of 7.9 km/s.

Going outside LEO (such as to the moon) merely requires refueling on-orbit. It also requires rough-field landing and takeoff capability.
"Merely"? We'll see. I hope they can do it.

Coming home from Mars merely requires propellant manufacture and all the logistics of liquifaction and storage and sub-cooling on Mars. Plus rough-field landing and takeoff capability. And refueling while in LEO. "Merely" again? Tall order, that one!

Aside from that, they merely have to get broadside entry to work, their new ceramic heat shield tiles to work, to verify there are not any hot plasma jets striking the windows during entry, and achieve landing and recovery with objects larger and more massive than anyone has ever dealt with before. Any one of those issues can cause complete vehicle loss in flight test. "Merely"? And that's just to make the basic LEO freighter application work.

Which assumes they don't crash during an off-site abort, since they have yet to even conceive a landing leg system that would work on uneven, soft, and/or rocky ground. Murphy's Law says that an off-site abort crash WILL happen! The stand-down to correct what went wrong will take 6-18 months, and cost $millions, if not $billions (if the lost vehicle was crewed; there is NOTHING as expensive as a dead crew). They'll essentially have to start flight-testing over again, because much of the bird will be a new design.

Getting all that done successfully is why I skoff at the notion of successful orbital flight anytime during 2020, or even the remote possibility of a cargo flight to Mars in 2022.

GW

Last edited by GW Johnson (2020-06-17 16:31:23)

SpaceNut · 2020-06-17 17:13:40

The fact that we have not a ready to go product is not unobtanium its just an idea ahead of its time for the materials that we have now.

The shuttle tiles fell into what we thought would not be obtainable but that was eventually proven wrong. Mars heat shields needed a new material and PICA was invented from materials research.

The current materials can be used on mars for many other purposes and one could be for a new crew cabin for a light mass rocket mad differently with the outer shell being made from the adapt umbrellas materials to withstand the heat of landing.

So lets refocus as to why we want light mass materials for a rocket to not only land on mars but to be able to return back to orbit many times....

tahanson43206 · 2020-06-17 18:04:41

For SpaceNut re #52 and suggestion to close out this interesting but ultimately unproductive topic ...

Thanks again to Calliban for taking the risk of trying out some challenging concepts.

I took a quick look at the periodic table before composing this suggestion for a new topic you might want to start in the Interplanetary transportation Index level.

Aluminum is a well established material for rocket manufacture. It has an agreed atomic weight of 26.981539 u (per Google)

Steel (to my amazement) is turning out to be Elon Musk's material of choice for his robust vehicle designs, and (again per Google) stainless steel was employed in a honeycomb heat shield for the Apollo space craft.

Carbon, with an agreed atomic weight of 12.0107 u (per Google) is a candidate material for a lightweight, strong rocket design.

I don't see any candidate elements below Carbon that would be suitable for consideration for this application, at "normal" temperatures and operating conditions.

If you are interested in starting a new topic, Carbon is a material that might well prove worthy of investment of time and thought by NewMars members.

kbd512 has already posted a significant number of times and in a variety of contexts, about the distinct advantages of various materials made of Carbon.

In the context of the "home made" Mars rocket, the discussion in this topic has covered a lot of possible applications for Carbon in construction of a sturdy Mars launcher.

I expect that the rocket engine(s) and turbopumps are going to ** always ** be made of alloys of metal, but potentially much if not most of the rest of the vehicle might (conceivably) be made of various arrangements of Carbon atoms.

FYI ... Google came up with a book citation that caught me by surprise, in the context of GW Johnson's recent post about his many articles collected in his ExRocketman blog.

How to Build Your Own Spaceship: The Science of Personal Space Travel
Piers BizonyJuly 28, 2009
Sold by Penguin
6
Buy as Gift

This is an eBook ...

Personal space travel is no longer the stuff of science fiction. The future is here: Civilians are launching into orbit. How to Build Your Own Spaceship takes readers on a fun and quirky trip to the forefront of commercial space travel-the latest technology, the major business players, and the personal and financial benefits that are ripe for the picking. Science-writer Piers Bizony's breadth of knowledge, quick wit, and no-nonsense explanations of the hard science in this emerging arena will satisfy even the most dedicated space fanatics. With practical advice (from picking the best jet fuel to funding your own fleet of space crafts), unbelievable space facts, and fascinating photos, Bizony's user-friendly guide to blasting off is a must-have ticket to the final frontier.

I bring this up because it might be useful as a model for how GW Johnson's ** real ** design work might be presented to the public.

Edit#1: I just took a look at the sample of the Bizony book available via Google .... This work is by a capable writer .... it occurred to me that he might be persuadable to consider at least ** thinking ** about co-authoring a book based upon GW Johnson's decades of work.

(th)

Last edited by tahanson43206 (2020-06-17 18:13:44)

SpaceNut · 2020-06-18 18:35:38

The near liquid fuel is where we get the bang for the buck but we still need the means to prove out the pressure for that fuel. This is from the triple point charts for the methane and for the oxygen if that were the only fuels that we could make but I think that others could be had to allow for it to work.

The temperature of the triple point of methane was determined as 90.6861 K ± 0.2 mK using the triple point of argon (83.798 K) as the reference. The reproducibility of this fixed point is at least as good as that of argon.

Knowing how much pressure for load and go with a bag is sort of the concept where the phase change is near to the pressure of the artificial tanks design.

https://encyclopedia.airliquide.com/

The normal boiloff gas is used in https://en.wikipedia.org/wiki/Advanced_ … lved_Stage

The IVF technology utilizes a lightweight internal combustion engine to use hydrogen and oxygen propellant boiloff (normally wasted when boiloff gasses are vented to space) to operate the stage including production of power, maintaining stage attitude, and keeping the propellant tanks autogenously pressurized, eliminating the need for hydrazine fuel and helium,:and nearly all batteries from the vehicle.

tahanson43206 · 2020-06-19 04:41:10

For SpaceNut re #54 and topic ...

In one of the posts by GW Johnson I've read recently, he talked briefly about the X-33 experimental rocket. The point he made (as I recall it) was that the builders were striving for the least possible weight/mass for the vehicle, and the result was so weak that the structure could not bear the weight of fully loaded fuel tanks.

This topic seems to be morphing into an exploration of the materials from which a home-made rocket might be manufactured on Mars, where Carbon is abundant and other materials will require some development work.

Given that metals (and particularly titanium) are likely to be needed to make rocket engines themselves, it is good to see that the Mars regolith contains some of them:

Magnesium, Aluminium, Titanium, Iron, and Chromium are relatively common in them. In addition, lithium, cobalt, nickel, copper, zinc, niobium, molybdenum, lanthanum, europium, tungsten, and gold have been found in trace amounts.
Ore resources on Mars - Wikipedia

In thinking about the X-33 example cited by GW Johnson, the materials chosen were dealing with the 1 gravity environment of Earth. I wonder if they would have done better on Mars.

(th)

SpaceNut · 2020-06-19 16:51:26

What we know so far is that cryogenic is not going to work, that 1 atmosphere gaseous source will not work but we can do liquids but which ones make sense with engines and mars insitu which we can make.

https://en.wikipedia.org/wiki/Liquid-propellant_rocket

https://en.wikipedia.org/wiki/Liquid_rocket_propellant

tahanson43206 · 2020-06-20 06:01:51

For SpaceNut re #56

Could you clarify why cryogenic fuel and oxidizer "are not going to work".

I agree that they are harder to work with, and that a search for liquids that can be manufactured on Mars for rocket launches is warranted, but I don't see any reason why refrigerated components are out of the question.

It may be (I'm hoping you will follow up) that you are thinking about the limited energy resources that will be available to Mars pioneers for a long time, and thus weighing the energy demands of refrigeration and compression of gases to make liquids.

Collecting the energy from sunlight to make fuel and oxidizer for launch is an inescapable energy investment. Perhaps you are thinking along the lines of avoiding the additional investment to liquefy these components, and then to maintain the liquefied state until launch.

Thus, it's possible you are guiding this topic toward finding fuel and oxidizer forms that can be held at ambient temperature on Mars without refrigeration?

My understanding is that there are a number of such chemicals, but that they all are hazardous to manufacture, to store, to move and to use in a vehicle.

(th)

SpaceNut · 2020-06-20 06:53:37

The wont work was for the bag materials for cryogenic fuels and that leaves the heavy metal tanks as the only option for them if we are not making composite tanks that have been tested by musk but was not used.

The bfr/starship landings for mars estimates for solar delivered on mission for a louis plan of only solar out paces the deliverables of 6 ships tonnage (flat laying flexible panels, batteries, plus support structures) from what I recall just to be able to refill 1 insitu processing for a return ship home with nothing remaining for the crew to make use of for power. Its that to which causes the argument of needing nuclear at a minimum of the nasa kilowatt projects krusty to be part of the plan.

tahanson43206 · 2020-06-20 08:01:38

For SpaceNut re #58

Thanks for the clarification. Vehicles made on Earth that are designed for cryogenic fuel and oxidizer are potential customers for an on-site cryogenic refueling station. The reminder of composite tanks is helpful for this topic, because (as I understand the theme) the topic is about building home grown vehicles on Mars. Since composite tanks are made largely of carbon, they should be of interest to Mars designers.

When I went looking for information about composite tanks, Google came up with a book title that covers design of liquid storage tanks:

Structural Engineering, Mechanics and Computation: SEMC 2001 (2 Volume Set)
By A. Zingoni

That book is NOT for the faint of heart!

The section Google showed was about fixed position storage tanks. Mars will need those too, but this topic is about storage tanks for use in rockets, so I assume the forces of acceleration must be added to the concerns facing engineers working on fixed site installation.

It seems to me reasonable to pursue composite tanks for the Mars home-made situation for a variety of reasons.

(th)

GW Johnson · 2020-06-20 10:18:22

One of the options used in liquid-propellant missiles was a minimal metal shell tank with a rubber bladder inside. You pressurize between bladder and shell to expel the liquids, which had to be room-temperature storables. There are no elastomers that don't shatter brittle at cryogenic temperatures.

There were a number of geometries to squeeze-the-bag to get the propellants out. Some were laterally-directed. Others were end-on, reverting the end like a piston into the rest of the bag. You could do this at low pressure to get just a net positive suction head for a turbopump assembly, but in most missile work, this was done at very high pressure for a pressure fed engine rig. Turbopumps were just too expensive to throw away in a one-shot missile. Heavy shells were not.

GW

Void · 2020-06-20 11:31:06

Thankyou, I was not aware of that trick.

tahanson43206 · 2020-06-20 14:14:37

For GW Johnson re #60

Thank you for the historical (and practical) perspective on pressure fed missile designs.

Visions of just such piston mechanisms were bouncing around in the minds of some of the contributors to this topic in recent days.

Your advice has finally won the day, that trying to accomplish a launch with propellants in gaseous form is a stretch too far for materials and methods that exist today. This topic has morphed (as I understand SpaceNut's hints) into a focus on what a homegrown Mars launcher might look like.

Now, with your welcome lesson on historical designs and actual practice, for using gas pressure to move liquid propellants toward the engines, it seems to me the topic has opened for consideration of such designs for the homegrown Mars launcher.

By historical analogy, when the North American continent was settled by adventurers from Europe, the state-of-the-art of water borne navigation was canoes of various kinds, constructed by the native inhabitants of the continent primarily for river navigation, but (as I was surprised to learn) extensively in South Florida.

https://accessgenealogy.com/florida/anc … system.htm

It was in southern Florida, however, that an indigenous people built the Western Hemisphere’s largest water transportation network. Between 300 AD and 1150 AD archaeologists think that the Mayami, Calusa and Tequesta peoples built hundreds of miles of canals. Some of the canals were as wide as 25 feet 1 Such a dimension suggests that there was very heavy canoe traffic on certain routes. Other canals were merely 6 feet wide swaths cut through the dense foliage of the Everglades and other smaller, wetlands. When linked together, this system enabled travelers and merchants to transverse the entire width of the Florida Peninsula; from the mouth of the Miami River to the mouth of the Caloosahatchee River. The southwest Gulf Coast of Florida contains many islands and tidal channels, which extended the range of canoes far beyond the mainland.

As the Europeans gathered on the shores of the North American continent (RobertDyck reminds us periodically of the example of NewFoundLand), eventually artisans began to replicate some of the water transportation systems invented in Europe.

I think it likely something similar will occur as Mars develops. The technology of Earth will remain superior to anything fabricated locally for a considerable time, but (I expect) eventually local inventors will find optimum solutions to various problems using local materials.

Thus, we can imagine that Mars residents will find metals to use for components that require them, such as rocket engines and turbines of various kinds, but develop materials for other rocket components that are best sourced (on Mars) from available supplies.

Stretching here a bit, I'm imagining that a liquid fuel such as methane might be pressure fed to a turbine that feeds an engine. The purpose of dividing responsibility this way would be to reduce the mass of the turbine, and the demands on the blades. For liquid oxygen, it seems to me unlikely a less demanding solution than the one developed for Earth launches is likely to evolve.

On the other hand, as SpaceNut has (seemed to me to have) hinted recently, perhaps there is a liquid oxidizer chemistry that would be practical on Mars, for which the ambient temperatures would favor storage and use in liquid form. In that case, a pressure fed component of the design might usefully support a less powerful turbine pump.

(th)

SpaceNut · 2020-06-20 18:33:09

I remembered earth atmospheric cooling of oxygen for use for rockets in the https://en.wikipedia.org/wiki/Air_turborocket and for the Sabre rocket Engine

https://futurism.com/the-byte/air-breat … on-engines

The SABRE engine "relies on a heat exchanger capable of cooling incoming air to −150 °C (−238 °F), to provide oxygen for mixing with hydrogen and provide jet thrust during atmospheric flight before switching to tanked liquid oxygen when in space."

So liquifying seems possible from cold pressured oxygen to be used for a rocket on mars as means for gaining orbit.

Since to deorbit and return to a safe landing on mars requires a metal tank filled with oxygen only needs to process the amount to get to orbit leaving the left over from cooling for the future landing. On would assume that we can liquify faster than we can use it so using the metal tank as an in between storage and mixing location seems to fit.

https://www.dailymail.co.uk/sciencetech … tests.html

The new engine creates its own liquid oxygen by cooling air entering the engine from 1,000°C to minus 150°C in a hundredth of a second – six times faster than the blink of an eye – without creating ice blockages

Seems we can adapt this technology to super cool gaseous oxygen for the application.

tahanson43206 · 2020-06-20 19:32:35

For SpaceNut re #63

You've made an interesting connection here.

One application that flows from Post #63 is the possibility of rapidly cooling gaseous oxygen on Mars (or perhaps even Earth).

One observation that occurs to me in thinking about the idea, is that the incoming oxygen is heated by the movement of the vehicle itself, and the cooling does not yield liquid oxygen, but instead delivers air to the combustion chamber at a low enough velocity so that it can be mixed properly with hydrogen. Hydrogen in that case is carried on board in liquefied form, and my understanding is that the liquid hydrogen is circulated in the coils of the cooling system to provide that instant cooling.

I'll try to adapt that idea to the Mars situation, where a rocket fueling station is in need of liquid oxygen to top off a vehicle that just arrived from orbit, and needs to go back quickly.

If there is a stash of liquid hydrogen that can be allocated for the cooling operation, then it seems reasonable to suppose that a feed of gaseous oxygen could be cooled substantially from Mars ambient temperature. Additional pressurization and cooling will no doubt be required to deliver the needed quantity of liquid oxygen to the lander's tanks.

What I understand of the basic idea seems like a useful way of "banking" cooling capability to rapidly deliver liquefied oxygen to an arriving vehicle. Variations of this idea (for rapid cooling of fuel and oxidizer) might be achieved by "banking" a supply of liquid CO2, and using that to cool the machinery for compressing and cooling hydrogen and oxygen for vehicles that need those elements for return to orbit.

For SpaceNut .... look what Google came up with when I asked for information about making liquid oxygen on Earth:

Search Results
Web results
The Rocket Company - Page 193 - Google Books Resultbooks.google.com › books
Robert Zubrin and the Mars Society have done a lot of work on the problem of making propellants ... mainly of CO2 , which could be broken down into liquid oxygen and liquid carbon monoxide . ... That would certainly do , wouldn ' t it ? " “ No question , ” said Fred . “ Then you could easily go direct to Earth from the surface .
Patrick J. G. Stiennon, David M. Hoerr - 2005 - Science

I was taken aback to find Dr. Zubrin and the Mars Society showing up in the top tier of results!

Edit#1: Following up ... I was curious to know what circumstances permit the existence of liquid CO2

Google came up with this:

Liquid carbon dioxide is the liquid state of carbon dioxide, which cannot occur under atmospheric pressure. It can only exist at a pressure above 5.1 atm, under 31.1 °C and above -56.6 °C. Its uses and applications include the extraction of virgin olive oil paste, fire extinguishers, and as a coolant. Wikipedia
Point group: D∞h
Bond angle(s): 180°
Μ (Polarity): non-polar

So a stash of liquid CO2 could be made ahead of time, and saved for a time when rapid cooling of oxygen and hydrogen are needed to top off a visiting space lander. The principle of rapid cooling of gas developed by British engineers for the Sabre engine could presumably be used to more rapidly deliver liquid oxygen and liquid hydrogen than would be possible by simply using ambient Mars atmosphere to cool the radiator fins. In performing the cooling function, the liquid CO2 would evaporate back to ordinary gaseous CO2 and be pumped or delivered to gas storage tanks where it would be saved for the next time of need.

This may not be the application you were thinking of when you first made the connection, but I think this is a useful idea for use on Mars, or perhaps even on Earth, if speed of production of liquid oxygen is important.

Edit#2: Here is the title of this topic, as created by Calliban: Compressed gas balloon rocket for Mars launch

It is interesting to note the wild swings of the posts around this topic, as we arrive back at something remotely similar to the original idea.

Now I am seeing balloons (or tanks) of oxygen and other suitable gases waiting patiently for the arrival of a customer vehicle which needs to be topped up with liquid fuel and oxidizer. Using the rapid cooling technique arising from SpaceNut's connection with the British Sabre concept, the gaseous stock could be fed into rapid liquefaction machinery using stored liquid CO2 as the cooling agent.

That would cover all the bases, it seems to me. We end up with gas stored in balloons (or tanks) in gaseous form, and in accordance with GE Johnson's recommendation, we end up with liquid fuel and oxidizer for use by a "real" rocket.

Not bad, SpaceNut!

Edit#3: Google found several citations for "how to make liquid CO2"

The first was a demonstration for a morning TV show ... the experiment demonstrated showed that when dry ice is allowed to warm up in a sealed container, it will convert to a liquid. It also demonstrated that the pipette used for the demonstration was destroyed by the pressure. So what I take from this first exposure to the procedure is that in order to use CO2 for rapid cooling as described above, it might be reasonable to build up a stash of dry ice, which does NOT have to be maintained at high pressure.

(th)

Last edited by tahanson43206 (2020-06-20 20:02:35)

tahanson43206 · 2020-06-21 07:43:35

This is a follow up to Post #64 in Calliban's compressed gas topic...

I'm hoping forum members with the education and experience needed will give some thought to how they might set up a small business on Mars to apply the ideas from Post #64 to deliver liquid oxygen to customers on an as-needed basis.

It seems unreasonable to me to build a business around holding liquid oxygen in tanks on Mars for extended periods while waiting for customers. Instead, it seems much more reasonable to build up stocks of oxygen in gaseous form, held under pressure in large tanks designed for the purpose.

At the same time, such a business would assemble a quantity of dry ice, which should be easier to maintain in a solid state than it would be to maintain oxygen in a liquid state.

Then, when a customer makes an appointment sufficiently in advance, the dry ice can be used as a high speed coolant for a process similar to the one developed by the British for the Sabre engine, which is able to cool hot gas in a short period of time by drawing heat from the gas into liquid hydrogen pumped through cooling vanes.

A detail that is not clear to me, and which (hopefully) someone in the forum can work out, is how to move large quantities of dry ice to the liquid format ahead of the time when it is needed for the rapid cooling operation.

(th)

SpaceNut · 2020-06-21 08:15:08

What this is driving is making use of the inflatable bags 1 Atm earth, which can be made at a lower level of energy to allow for the sabre cooling system to basically be used for an on demand system.
Every thing for insitu refueling is starting with using the Co2 atmosphere and the finding of water in a low energy processing yield for use to create gaseous hydrogen, such that we can use it in methane creation with the already captured co2 and to create the oxygen for use from simple electrolysis. Where as the methane is created via a number of catalyst processes of which each have there own unique energy input requirements.
While the inflatable bag is in need of higher pressures for the tank above 1Atm earth its seems possible to use the sabre cooling that makes it possible to take a higher inlet pressure from the bag tank for the conversion to liquid that a rocket needs.

elderflower · 2020-06-21 09:31:51

https://commons.wikimedia.org/wiki/File … iagram.svg

So liquid CO2 can exist at pressure above about 5 Bar.

tahanson43206 · 2020-06-21 10:08:29

For elderflower re #67

thank you for that ** really ** helpful image ... that is most certainly a good example of a picture being worth (lots) of words.

However, I am hoping to invite a further contribution, to benefit someone who might be in a position to fund a refueling service on Mars in coming decades. That person will (no doubt) investigate to see how liquid oxygen is made on Earth, how it is stored on Earth, and how it is delivered to customers, whether that be for rocket launches or for industrial applications.

What SpaceNut's insight about the British Sabre engine brings to light is the possibility that it might turn out to be practical to use liquid CO2 in the place of Hydrogen, to rapidly cool gaseous oxygen (stored in a convenient nearby tank) to the point it becomes a liquid.

In a previous post, I reported finding a YouTube video showing the conversion of a small quantity of dry ice to liquid CO2 in a science experiment prepared for a school aged audience. I'm hoping someone can contribute to ** this ** topic a description of how a large quantity of liquid CO2 can be prepared (and saved for use) given a correspondingly large quantity of dry ice as feed stock.

The proposition at hand is that liquid CO2 could be used to rapidly convert gaseous oxygen (on the ground on Mars) into liquid oxygen suitable for delivery to a customer needing refill of a rocket lander.

In coming decades, there should be a substantial and growing demand for liquid oxygen to fuel space going vehicles on Mars.

I am pursuing the possibility here, that the use of liquid CO2 would provide a competitive advantage of one supplier over another who tries to use traditional air cooling for oxygen liquefaction machinery.

Since both suppliers will be drawing solar energy for their undertakings, the supplier who uses that solar energy most efficiently while avoiding losses of product along the way will be able to price service at a level customers will find attractive.

Edit#1: SpaceNut in a parallel series of posts is thinking about compressing gaseous oxygen in a flying vehicle. ** This ** subtopic is intended (and offered) for thinking about ground-based supply depot operations.

(th)

Last edited by tahanson43206 (2020-06-21 10:10:36)

SpaceNut · 2020-06-21 10:55:56

Since we are talking the basalt fiber bag or Kevlar in lots of topics the equipment should become less experimental as we can now show we can use it for many physical planned items for multiple uses. The equipment also now get better efficiency of use for production which would drive down material reprocessing for other uses. Since the baseline fiber is just what you do with it afterwards that build up strength for making braids and cables and so much more to weave into inflatable structures. These woven tubes can be used for habitat space areas once sprayed with a UV setting up resin such as in the airplane topics. This makes them set up just like fiberglass and it becomes ridged for use as desired in the my hacienda topic..

SpaceNut · 2022-10-22 16:56:32

This topic just got a boost from cryogenic temperature the polymer bladder On-Orbit Propellant Transfer topic as this would allow for a telescoping booster section with this internal bladder for a mars ship.

New Mars Forums

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#51 2020-06-17 16:26:45

Re: Compressed gas balloon rocket for Mars launch

#52 2020-06-17 17:13:40

Re: Compressed gas balloon rocket for Mars launch

#53 2020-06-17 18:04:41

Re: Compressed gas balloon rocket for Mars launch

#54 2020-06-18 18:35:38

Re: Compressed gas balloon rocket for Mars launch

#55 2020-06-19 04:41:10

Re: Compressed gas balloon rocket for Mars launch

#56 2020-06-19 16:51:26

Re: Compressed gas balloon rocket for Mars launch

#57 2020-06-20 06:01:51

Re: Compressed gas balloon rocket for Mars launch

#58 2020-06-20 06:53:37

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#59 2020-06-20 08:01:38

Re: Compressed gas balloon rocket for Mars launch

#60 2020-06-20 10:18:22

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#61 2020-06-20 11:31:06

Re: Compressed gas balloon rocket for Mars launch

#62 2020-06-20 14:14:37

Re: Compressed gas balloon rocket for Mars launch

#63 2020-06-20 18:33:09

Re: Compressed gas balloon rocket for Mars launch

#64 2020-06-20 19:32:35

Re: Compressed gas balloon rocket for Mars launch

#65 2020-06-21 07:43:35

Re: Compressed gas balloon rocket for Mars launch

#66 2020-06-21 08:15:08

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#67 2020-06-21 09:31:51

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#68 2020-06-21 10:08:29

Re: Compressed gas balloon rocket for Mars launch

#69 2020-06-21 10:55:56

Re: Compressed gas balloon rocket for Mars launch

#70 2022-10-22 16:56:32

Re: Compressed gas balloon rocket for Mars launch

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