Space Business Blog Article on NewSpace Startup Accelerators

Normally I don’t just do a blog post linking to another blog post, but Colin Doughan’s article on NewSpace startup accelerators over on the Space Business Blog is well worth reading. Colin’s a good friend I’ve known for several years, and who’s given me a lot of advice and mentoring at Altius over the years. He’s wrapping up his MBA (while working full-time for one of the aerospace primes here in the Denver/Boulder area), and this blog post was part of his final semester MBA efforts.

The article discusses ways to take the YCombinator model and adapt it for accelerating aerospace startups. I think this industry has a little too much of a “swing for the fences” mentality, where everyone wants to pitch asteroid or moon mining startups, or build an orbital rocket ship. Having an accelerator like this might make it a lot easier for smaller aerospace startups to launch, and get quickly to an exit point. Once we start getting some successful 2nd or 3rd generation space entrepreneurs (ie entrepreneurs who have been through 1-2 successful startups already),  I think it will be easier to attract outside investment into the industry because you’ll have more teams with proven trackrecords. You’ll also see more of a NewSpace angel community that has investors who are former NewSpace entrepreneurs, who understand the nuances of the industry, and are better able to make decisions about space startup investments. Right now we’ve got some awesome angels investing in space who made their money in IT or other industries (thinking Steve Jurvetson, Stephen Fleming, Esther Dyson, etc), but I think things will start moving even faster when you start seeing investment money coming from angels who made their money in this industry.

Anyhow, go to Colin’s blog to read his article and comment on it. I’m locking the comments on this thread to encourage people to go over to his blog and comment there.

Posted in Business, Commercial Space, Entrepreneurship, Space Development | Leave a comment

Venusian Acid-Cooked Turkeys, or Why I Still Read Blog Comments…

In a world where many blogs and websites are shutting down comment threads, I think we all need the occasional reminder of why we permit comments. Sure, you often learn something new from other people’s inputs, and sometimes get corrected when you step beyond the limits of your actual knowledge-base too far. But sometimes you read a comment that’s so brilliant, you just have to look up the commenter’s email, and beg them for permission to repost their work of art. This was one of those times.

In case you want the backstory, it all started with a discussion about cooking turkeys in the Venusian atmosphere on Rand’s blog, when George Turner penned this brilliant rant about how Real Men™ cook their turkeys (I would strongly suggest putting away any beverages before reading further…):

You guys have obviously never had a properly prepared inert-gas high-pressure acid-cooked turkey, probably because you let your mother-in-law be in charge of cooking the bird. It took men 200 years to convince wives that dunking the turkey in propane-fueled boiling oil was not only fine, it was wonderful, because all women folks know is their Betty-Crocker Easy-Bake ovens.

Well let me tell you, acid is good for meat, and breaks down connective tissue, fats, and tenderizes it. Run the pH the other way and it turns into soap and you might as well bite into a urinal cake.

Venus is not for the timid, or people too afraid to shove a fat bird out the airlock and let the harsh laws of thermodynamics do the work. Venus is for men. Men who like to eat meat – cooked in fire and acid and seasoned with the Devil’s own mix of volatiles boiled up from the pits of hell.

If the thought of Thanksgiving Dinner on Venus gives you the heebie jeebies, you don’t even need to think about plunging into the roiling atmosphere with nothing but a cheap plastic heat shield and a thin balloon to save you from the crematorium that yawns down below. So man up, dangle the bird into the depths of the Stygian hell, feast as someone who walks between worlds and lives on an airship that rides the hell born winds 30 miles above a surface so hot it glows visibly red.

Ride that Venus airship, live on it. Drink the harshest ale till you he see double, then hold your breath and walk outside in the acid rain to pee over the side, knowing that lesser men bow their heads in shame, sitting in Portland stirring the mashed potatoes as their wife frets over the anonymous Butterball in the Oster Roaster, waving her arms and telling you to check the yams. One man is living, however brief and harsh that life may be, and one has never truly lived, never tasted a naturally acid-cooked Venusian bird, never ridden the microbursts and whirlwinds of an alien planet, never done anything to merit remembrance, like putting down roots on a new world and cooking a bird so tasty that people are still trying to recreate the meal centuries later.

You have to put away your fears of one bad meal, a miscooked bird, and embrace the future, mankind’s future, and realize that there’s more than one way to pluck a chicken.

That was just plain beautiful. Thank you, George.

Posted in Humor, Venus | 7 Comments

Venus ISRU: ISRU Development Phases

In the last post in this series, we discussed methods for gas phase processing once the easily condenseable atmospheric constituents had been condensed-out. Before continuing on to a discussion about various processes for creating chemical precursors, I thought it would be useful to discuss various phases of Venusian ISRU development, with increasing levels of sophistication. This will help provide some context to further discussions.

Phase 0–Terrestrial Analog ISRU Prototyping: This is where we’re at now. As far as I know there has been almost no experimental development of the sort that some of our commenter have suggested which would use simulated Venusian atmosphere to attempt various approaches for extracting the different constituents for further processing. Obviously that which hasn’t even been tried in the lab is nowhere near ready to try in situ. This stage will likely be characterized by small, non-flight like, breadboard/brassboard-level prototype processes.

Phase 1–Venus In-Situ Demonstration: The first real Venus ISRU development phase will likely be in the form of small experiments mounted on robotic atmospheric balloons. We’re likely talking about experimental apparatus of less than 200kg, which are not so much focused on producing large masses of extracted materials, but just demonstrating and validating basic extraction processes. These steps will likely be focused on the concepts  we’ve talked about so far of condensing out and separating condenseable species, and processing the atmospheric species to remove key hazardous materials, to demonstrate the ability to extract safe feedstocks for future larger-scale processes.

Phase 2–In-Situ Propellant Production and ECLSS Revitalization: This is the point at which the first steps beyond what we’ve already discussed will be taken. This phase may start with unmanned systems, demonstrating the ability to refuel rocket stages for transportation back into Venus orbit, and to provide fuel for Venus orbit propellant depots. But this phase will likely also include demonstration of the ability to revitalize the breathing air and drinking water for manned missions. This may also include trying to create enough lighter-than-CO2 gas to provide buoyancy for the robotic and manned systems. This stage isn’t necessarily about creating voluminous open habitat spaces and floating cities. Depending on the rocket approach taken for transportation between the cloud level and orbit, this could involve processing hundreds of tonnes of atmosphere into propellants, and tens of tons into lifting gasses and life support elements. At this point most chemical processing will be limited to that necessary to create propellants. Depending on what propulsion style makes the most sense, this could be LOX/LH2, LOX/Methane, or LH2 or Ammonia for nuclear thermal, solar/microwave thermal, or solar/laser thermal propulsion systems. These can mostly be created by simple one or two step processes from the basic atmospheric constituents previously discussed.

Phase 3–Small Settlements: At this phase, permanent settlements are first being attempted. So in addition to processing the atmosphere to create propellants for flights in and out of the Venusian atmosphere, and creating lifting gasses for supporting those smaller facilities, we’ll now be talking about creating large amounts of breathable air and water for filling these colonies. Also this phase will likely include the creation of simple construction materials to try and reduce the amount of material that needs to be shipped from earth. This will likely start requiring taking the initial chemical feedstocks and performing several processes to create materials such as carbon fiber, simple polymers, and sulfurcrete. These materials would be used for the structure of the settlements, and possibly even the atmospheric barrier film. This phase will be focused on the low-hanging fruit of materials that would require the most shipping mass from earth, but that are easiest to produce on Venus. Peter Kokh had some clever acronym for this for lunar ISRU, but I’m forgetting it at the moment. But basically, the more processing steps necessary to get to an object, the more likely it would be best to still import this from earth.

Phase 4–Advanced Settlements: At this phase large-scale permanent settlements will exist, and even some limited mining of the surface of Venus will likely have started. As this phase progresses, more and more materials of increasing complexity will be sourced locally, including some simpler metals, and more advanced plastics and composites. As this phase continues imported materials will focus on high-value hard-to-manufacture items like advanced electronics, complex machinery, etc. I think this Phase while interesting is probably beyond the scope of this series. If we get to this phase, we’ve “already won”.

 

Next Up: Basic Chemical Precursors for ISRU Development Phases 2 and 3

Posted in ISRU, Space Settlement, Venus | 17 Comments

Venus ISRU: Gas Phase Processes

In the last post, we talked about methods to condense out the five most readily condenseable constituents of the Venusian atmosphere (sulfuric acid, water, sulfur dioxide, hydrogen chloride, and hydrogen fluoride). In some ways the next steps of the gas phase processing could be thought of as continuations of that process.

At this point in the process, the remaining constituents (assuming you’ve properly removed the previous-listed five condenseables) can be lumped into two categories:

  • Semi-reactive gasses like Carbon Dioxide, Carbonyl Sulfide, and Carbon Monoxide
  • Neutralish gasses like Nitrogen, Argon, Helium, and Neon

There are a couple of ways of proceeding from here. One thought to keep in mind though is that due to the large amount of CO2 in the atmosphere, you’re least likely to care about collecting it efficiently–it’s the other trace constituents that are worth gathering. The quickest way of separating out the other elements from the CO2 would be to do what someone suggested in the previous comments thread–freeze the CO2. With a freezing point of only -78C, the previous processes have likely already chilled the Venusian atmosphere fairly close to this temperature anyway. The phase change will take a lot of energy, but if after separating out the other constituents you allow a good fraction of the CO2 to be sublimed away on your refrigeration processor’s radiator (assuming you’re using active refrigeration instead of the heat-pipe trick), not all of that energy will go to waste.

In the process of freezing out the CO2, assuming you are doing this in some sort of a batch process, the pressure is going to drop by about a factor of 20x. This may raise the concentration of the carbonyl sulfide enough to get it to condense out as a dew that can be removed, since the air stream will now be lower than the boiling point of the COS, and the effective concentration will be increased by about 20x since you just got rid of most of the atmosphere.

If that’s successful, the only semi-reactive species that will be left is Carbon Monoxide. Carbon Monoxide’s boiling and melting points are much lower, so you probably won’t be able to remove it at this step. You have a few approaches you could take to removing the Carbon Monoxide. You could try to distill it out if you’re processing the rest of the more neutral gasses to individually separate them. Or you could mix the neutral gasses with oxygen and run it over a warmed catalytic converter. Or you could try reacting it with warmed sulfuric acid–since carbon monoxide is a fuel and sulfuric acid is an oxidizer. Or you could just live with it as an impurity. Or there might be some sort of way to filter it out electrochemically. Not sure which approach is best, but my guess is one of the first two.

Once you have the carbon monoxide removed, you’re down to neutral gasses like Nitrogen, Argon, Helium, and Neon. It may make sense to separate these further via distillation if you already have them this cold. This can proceed using similar equipment to what is used terrestrially for producing various industrial gases. For instance using either Linde’s or Claude’s processes to chill and liquify the gasses. If on the other hand you don’t yet have need for the separated gasses, you could just leave them mixed together as the buffer gas to mix with oxygen for breathing purposes. It should be noted that going into this step, if you’re down to just the neutral gasses, the Nitrogen is still about 99.8% of what you have. The concentration of Argon at this point is only 0.2%, which is actually lower than the 0.9% you find on earth, but Helium and Neon are both at much higher concentrations than they are in Earth’s atmosphere. So it might be worth processing them out via some sort of fractional distillation process.

Once you’ve removed the neutral gasses and dealt with (or not) the carbon monoxide, you can take whatever portion of the carbon dioxide you want to keep for chemical processing, and allow the rest to be vented overboard, using them to chill the hot-end heat exchanger on your active refrigeration system if you’re using one.

At this point you’ve now broken the Venusian atmosphere out into its constituents, and possibly chemically altered a few of them (reacting some of the Sulfuric acid to release water, or maybe catalytically converting the carbon monoxide). At this point you’re ready to start doing some basic chemical processes to try and create some chemical precursors.

Next Up: Basic Chemical Precursors ISRU Development Phases

Posted in ISRU, Space Settlement, Venus | 7 Comments

Venus ISRU: Condenseables [Updated]

[Note: Karl caught an important oversight in the comments. With a concentration of 150ppm and a boiling point of only -10C, Sulfur Dioxide (SO2) should also be considered a condenseable. It's dew point is likely pretty close to water's. So I've updated this blog post to reflect that important oversight on my part.]

In my opinion the first place to start with ISRU processing of the Venusian atmosphere is to try and remove all five of the easily condenseable atmospheric constituents: Sulfuric Acid, Water, Sulfur Dioxide, Hydrogen Chloride (in the form of Hydrochloric Acid), and Hydrogen Fluoride (either directly or in the form of aqueous Hydrofluoric Acid). I think this is the best course of action for a few reasons:

  1. As the Venusian atmospheric constituents with the highest boiling and melting points, they are probably the easiest to extract from the atmosphere.
  2. The four easily condenseable constituents with hydrogen are the only local sources of hydrogen for a Venusian colony, and thus extremely valuable
  3. Sulfuric Acid is corrosive enough that removing as much of it as possible from the gas stream will probably make all downstream processes a lot easier/more-reliable.

Sulfuric Acid Extraction
In the case of the Sulfuric Acid, the freezing point of the acid is 10C, and the boiling point is very high (337C). This high boiling point and freezing point mean that of the four condenseables, the Sulfuric Acid will probably be the easiest one to extract. Especially when you factor in that in the cloud altitudes, the Sulfuric Acid is probably pretty close to its saturation density. Unfortunately the sources I could readily find didn’t give a clear indication of if this was truly the case or not. I’m not even sure if we know.  If it really is at saturation density already, condensing it out of the air might take the form of a fog fence, or more likely some form of atmospheric water generator.

The fog fence would basically be a fine mesh net, probably of PTFE fibers, placed in front of the flow of Venusian air. Some sources I’ve read have indicated that the sulfuric acid droplets are likely positively charged electrostatically, so it might be possibly to electrostatically charge the the fog fence net to increase its ability to capture droplets with less pressure drop through the mesh. I’m not sure what the best method of getting the droplets back out of the mesh in order to collect the liquid. One possibility would be occasionally reversing the electrostatic polarity on the mesh net. Or possibly nothing may be needed as the mesh gets enough sulfuric acid trapped in it.

If the sulfuric acid droplets aren’t high enough density to make the fog fence work, you could chill the air until the sulfuric acid reaches its dew point and starts precipitating onto the cooling surfaces. Due to the higher boiling and melting points of sulfuric acid compared to the water, it should condense out first before the water starts condensing. Once most or all of the Sulfuric Acid has been removed, the remaining ISRU steps should become significantly easier.

Water Extraction
After the Sulfuric Acid has been entirely or mostly removed from the gas stream, the next step is to remove the water. There is supposedly more water vapor than sulfuric acid at the altitudes in consideration, if the sources I’m reading are correct. To collect the water, the best approach is probably to chill the air until the water reaches its dew point, and then it will collect on the chilling surfaces. I’m not sure how far you have to chill the air to get this to happen at the concentrations of water we’re talking about. I saw many sources describing the dew point of water in a high-pressure carbon dioxide atmosphere (for CO2 scrubbing systems for plants), but not much on the dew point of water vapor in lower pressure carbon dioxide at this low of concentration of water.

If it turns out for instance that you have to chill the air so far that the water freezes onto the cooling surfaces instead of condensing on it, some sort of wet dessication approach could be used instead. In that approach, you use a brine solution to absorb water from the air, then pull a vacuum on the brine and heat it a bit to boil-off the captured water. I’m not sure which makes more sense in this situation. But those are the two main routes. Alternately, Sulfuric Acid is actually a strong desiccant, absorbing water out of the air to make a more dilute sulfuric acid. So it may be that you can get some of the water vapor out of the air with the sulfuric acid, and then distill out the water via boiling or lowering the pressure till the water boils out.

Sulfur Dioxide Extraction
The next major constituent to extract is the Sulfur Dioxide. With a boiling point of -10C and a freezing point of -72C, the Sulfur Dioxide should be condenseable using similar cooling processes to what was used for the Sulfuric Acid and the water.

Hydrogen Chloride and Hydrogen Fluoride Extraction
There are two possible routes for collecting the remaining two easily condensable species. First, both of them absorb into water to form hydrochloric and hydrofluoric acid. It may be that if the water extraction is done right, it will remove a decent amount of the HCl and HF at the same time–if you can get it to absorb into the condensed water fast enough. Alternately, you could extract them by continuing to chill the air until they condense out. In the case of HF, its boiling point is about room temperature, but in the case of HCl, the boiling point is cold enough (-85C) that it may not be worth trying to get it out if you can’t capture some of it in the water condensation step. Fortunately Fluorine is a more useful element than Chlorine, so the fact that it’s likely easier to extract than the HCl is useful. It may still not be enough to be worth the hassle, but if it can be extracted, HF is a key chemical precursor to creating fluorocarbons, which as one of the few materials that can handle concentrated sulfuric acid, will be really useful for exposed surfaces on these colonies.

Heat Pipe Cooling Source?
One other point worth making is that a potential heat sink for chilling the air was suggested in one of the previous comment threads–heat pipes connected to higher in the atmosphere. The Venusian atmosphere at this altitude drops 30-40K per 5km. I don’t know if it is at all practical to use a say helium balloon to support a heat exchanger at a higher altitude with an insulated heat pipe to transfer heat from the lower altitude collector and dump it into the cooler air above. If it is, it may enable much more rapid processing of the atmosphere since it would provide you with both a low-power way of pulling a ton of heat out of the atmosphere for extracting condenseables, but also as a way of keeping a relative inflow of air into the collector (since higher altitudes have faster winds on Venus).

If that proves to be impractical, wind or solar generated power could be used to run a traditional electric refrigeration circuit. Heat pipes just seem like a more elegant way of solving the problem.

What to do with the Sulfuric Acid?
Once you have the sulfuric acid extracted, there are several things to do with it. First off, it might be worth leaving some of it as sulfuric acid, either diluted with some of the water, or in concentrated form. But most likely most of the sulfuric acid is best broken down chemically to release the hydrogen (in the form of water), and eventually release the sulfur for use in sulfurcrete. The two simplest options I can see for making this work are to react the sulfur either with hot graphite or with hot carbon monoxide. Either of those should result in Sulfur Dioxide, Water, and Carbon Dioxide. The carbon monoxide route is likely easier to get to chemically than graphite, so is probably the better method. In this reaction it’s probably not worth trying to capture the CO2 or SO2 per se, since they’re already fairly abundant in the atmosphere, so really you’re just breaking down the sulfuric acid to release the hydrogen in the form of water.

Once you’ve done all of these steps, the air has had its most corrosive elements removed from it, and you’ve got water which is useful both as water itself, and as a source of hydrogen for all sort of other things (such as rocket propellants and plastics). There’s still a lot of details to be sorted out here on the best approaches for removing condenseables, particularly by someone who has a strong background in chemical engineering. But I think this provides a decent introduction to some of the approaches.

Next up: Gas-Phase processes.

Posted in ISRU, Space Development, Space Settlement, Venus | 19 Comments

Eating My Broccoli*

This is just a sort of public service announcement. I’ve got a lot of ideas for various blog posts right now, but I’m going to try and actually exert a little self-discipline, and finish up with the Venus ISRU series before starting in on a new topic. Hopefully I can get everything squared-away before I get swamped with this year’s NASA SBIR Silly Season.

*Note: I actually like broccoli, so maybe brussel sprouts are a more apt analogy?

Posted in Administrivia | 1 Comment

Random Thoughts: Inspiration Venus?

This morning, Grant Bonin (of the UTIAS Space Flight Laboratory) sent me a very interesting JBIS paper from about 6 years ago, discussing a manned-flyby/robotic-telepresence expedition to Venus. In light of the Venus ISRU series, I thought it worth doing a short summary of his excellent JBIS paper.

Some highlights of the proposed mission concept:

  • The mission concept would send a team of 4 researchers and a mix of several solar-powered upper atmosphere UAVs/blimps and a few surface rovers to Venus, which would be designed to be teleoperated by the researchers.
  • Upon the initial arrival at Venus, the robots would enter the Venusian atmosphere and in the case of the rovers land.
  • The researcher’s vehicle would perform a powered polar flyby of Venus, placing itself into an orbit with approximately the same velocity as Venus, but in a plane inclined to Venus’s orbit. This would keep it within 45 light-seconds of Venus for over a year of science operations (giving a worst-case round-trip signal delay of 90s).
  • During the science mission operations, a small electric thruster on the researcher’s vehicle would maneuver the spacecraft in a way that as it passed back through the plane of Venus’s orbit twice per orbital year, it would be just outside of Venus’s gravitational sphere of influence.
  • After the science period, the electric thrusters would maneuver the researcher’s vehicle to perform another powered flyby of Venus sending it back into an earth-crossing trajectory, for a total round-trip time of 2 earth years.
  • The two powered swingby maneuvers require ~250m/s each (with a 300km periapsis altitude), and the four node-shifting maneuvers total less than 1000m/s of delta-V on the electric propulsion system.
  • The initial departure to Venus would have a much lower C3 than iMars (8.55km^2/s^2 vs > 40km^2/s^2), making it easier to launch a decent mission stack  using existing upper stages.

The cool thing being that by entering this flyby trajectory, you get most of the benefits of having people near the robots to teleoperate them without the delta-V penalty of entering and departing Venus’s orbit, which would take around 8km/s of delta-V if performed entirely propulsively. While this hasn’t been studied in anywhere near as much detail as Inspiration Mars has, and at least with current launch costs is likely much further out of the reach of a privately funded venture, it’s still an intriguing concept that would be far cheaper than say a manned Mars mission.Anyhow, I just wanted to present this concept for discussion.

Posted in Space Exploration, Venus | 6 Comments

Venus Terraforming Open Thread

There have been several comments in the other Venus posts about terraforming. I don’t have a lot of personal opinions or ideas on the topic, but would like to provide this open thread for people to comment to their hearts’ content about Venus terraforming, how to do it, and if it’ll ever make sense.

In the meantime, I’ll get back to work on the rest of the Venus ISRU series.

Posted in Open Thread, Venus | 14 Comments

Venusian Rocket Floaties

While doing research previous in preparation for the Venus ISRU series, one of the questions that I knew needed a good answer was “how do you actually send vehicles to/from a floating cloud colony?” Unlike the any other near-term manned spaceflight destination, there isn’t a fixed point of land that you can touch-down on. Also, with its thicker atmosphere and only slightly lower gravity, launch from Venus will likely take two stages. How do you recover stages if they can’t return directly to launch site? If you can’t come up with a good answer to these questions that doesn’t require crazy advanced technology, it could be a showstopper. Because a flying cloud city isn’t very useful if you can’t get to it.

This morning, I had an epiphany.  One of the papers I had read over the past year or two about Venus missions was a paper by Geoffrey Landis on low-altitude Venus balloons[1]. One of the mind-blowing conclusions from this paper was that you could make a 1mm thick titanium spherical pressure vessel about 3.8m in diameter that could both survive reentry, and function as a “balloon” that would hover at around 5-10km altitude. This got me thinking…

Rocket stages are relatively low density when empty… Could you get a rocket stage post-burnout to float in the Venusian atmosphere? If so, could you do it at an altitude high enough that the temperature wouldn’t destroy the stage?

Short answers: Yes, and maybe.

In order to figure this out, I needed a few pieces of information. First, I needed a good estimate for the atmospheric density on Venus with respect to altitude. It took some digging, but I eventually found this table in another paper by Geoffrey Landis[2]:

VenusDensPressTempvsAlt

In case you’re wondering, the best curve fit I could get (R=.99991) for the first 60km was rho = -0.000340*H^3 + 0.055606*H^2 – 3.184604*H + 64.563149

Because the floatation altitude is the altitude at which the density of the stage equals the atmospheric density, we need to estimate the density of the empty stage. For this we need the inert mass of the stage and the approximate external volume of the stage. To simplify the volume calculation, we’re assuming that the only volume in the stage is the tanks themselves. This is a bit conservative, as the volume of engines and other structures also helps a tiny bit, but it’s much easier to get an estimate of the tank volumes than any of the other relevant volume numbers. Even tank volumes typically aren’t published, so we estimated them by taking the propellant load, estimating the tank mixture ratio (unless we knew it), estimating the propellant bulk density at launch, and estimating the amount of ullage space. I created a spreadsheet to calculate these density numbers, and to then estimate the resulting “flotation altitude” and the temperature at that flotation altitude[3].

The end result was:
VenusRocketFlotiesResults

A couple of key takeaways:

  • All of the stages could float at altitudes >5km
  • LOX/LH2 stages tend to float higher than LOX/Kero stages (fluffier tanks)
  • More mass efficient stages (higher pmf stages) tended to float higher
  • The pressures at this altitude are in the 30-40bar range, so you’d want to keep the tanks themselves pressurized enough that the tank was always a little bit higher pressure than the outside atmosphere. This could be done by letting the residual cryogens boil, and using a relief valve set to some nominal say 15-20psid setting.
  • The temperatures are all still a bit on the high side. No metal parts would likely fail, but this is hot enough that unless cooled (either via active refrigeration or by boiling-off a coolant), any electronics or plastic components would fail.

Anyhow it’s an interesting idea in many ways similar to ocean recovery, but without the abrupt interface issues with ocean recovery. You’d probably want to use a vehicle purposely designed for this application, both with temperature control for all sensitive hardware, with optimized bouyancy, and with corrosion resistant external coatings.

But isn’t it cool to think of a disembodied Centaur tank flying around like a derigible at 30,000ft?

[1] Landis, G., “Low-altitude Exploration of the Venus Atmosphere by Balloon.” AIAA-2010-268
[2] Landis, G., LaMarre, C., and Colozza, A., “Atmospheric Flight on Venus.” AIAA-2002-0819
[3] Venus Rocket Floaties Spreadsheet

Posted in Launch Vehicles, Space Transportation, Venus | 27 Comments

Venus ISRU: What Do We Have to Work With?

In the last mini blog-post, we talked about some of the benefits of atmospheric-feedstock ISRU. But that leads to the question, what materials are there in the Venusian atmosphere, particularly in and around the 50km zone? While chemical engineering may limit your ability to rearrange elements from the atmospheric constituents into an end-product, if that element isn’t available in the atmospheric constituents, you’re probably going to have to bring it from earth.

While I’ll go into more detail about the sulphuric acid and water vapor concentration in a future blog post, here are links to two tables (one from wikipedia, and another from a Purdue planetary science lecture). With atmospheric density at 50km being approximately 1atm, and with CO2 being most of the atmosphere, the bulk density is probably just a little under 2kg/m^3. I could get more precise than that, but that’s a decent rule of thumb. So the key atmospheric constituents at 50km, their relative abundance, and their mass density per cubic meter are (assuming I’m doing my math correctly):

  • Carbon Dioxide (CO2): 96.5% of the Venusian atmosphere is CO2. I’m not positive if this varies much with altitude in the ranges we’re talking about. But this would be approximately 1.93kg/m^3
  • Nitrogen (N2): 3.5% of the Venusian atmosphere is gaseous nitrogen. This works out to about 70g/m^3
  • Sulfur Dioxide (SO2): 130-150ppm in the Venusian atmosphere, which works out to 260-300mg/m^3
  • Argon (Ar): 65-70ppm, or about 130-140mg/m^3
  • Oxygen (O2): 30ppm or about 60mg/m^3 [Note: this one is only listed on the Purdue site]
  • Water Vapor (H2O): 20-30ppm or about 40-60mg/m^3. Compared this to the driest place on earth in the Atacama desert near the ALMA observatory in Chile, which had 200ppm water vapor at 5km altitude (.74kg/m^3 atmospheric density), which assuming I didn’t make math mistakes works out to ~145mg/m^3 [Note: I wasn't able to find anything on how this varies with altitude, so I'm just going with the raw numbers for now, and assuming they still hold at 50km.]
  • Carbon Monoxide (CO): ~17-20ppm or about 35-40mg/m^3
  • Helium (He): ~12ppm or about 24mg/m^3 [Note: This one was only listed on the Wikipedia site, and I don't know how much it varies with altitude]
  • Carbonyl Sulfide (OCS): 10ppm or about 20mg/m^3 [Note: only shown on the Purdue site]
  • Neon (Ne): 7-9ppm or about 15-18mg/m^3
  • Sulfuric Acid (H2SO4): I had a hard time finding good numbers for this, but according to Figure 3 on this page, at 50km, the abundance works out to ~14mg/m^3 or about 7ppm. So, between sulfuric acid and water vapor, you have about half as much mass per cubic meter as water vapor in the air near the ALMA observatory in the Atacama desert in Chile. Bone dry by terrestrial standards, but sopping wet compared to say the Moon.
  • Hydrogen Chloride (HCl): 0.1-0.6ppm or between 0.2-1.2mg/m^3
  • Hydroflouric Acid (HF): 1-5ppb or between 2-10µg/m^3

Of these components three of them (water, sulfuric acid, and hydroflouric acid) have liquid phases at room temperature, which means they can likely be condensed out as liquid phases relatively easily before processing the rest of the gas-phase constituents. Also, the HCl vapors dissolve so readily into liquid water (forming a hydrochloric acid), that they may also be effectively “condenseable.”

So elementally, we have lots of Carbon, Oxygen, Nitrogen, and Sulfur, decent amounts of Argon, Helium, Neon, and Hydrogen, and trace amounts of Chlorine and Fluorine. What can you do with these building blocks, assuming you can make the chemical engineering work to take these feedstocks and convert them to the outputs you want?

  • Breathable air
  • Drinkable water (from the water vapor and chemically extracted from the sulphuric acid)
  • Chemical rocket propellants (LOX, Methane, Hydrogen, and with a lot more work maybe some storables like N2O, N2O4, Hydrazines, H2O2, and storable hydrocarbons and alcohols)
  • Most plastics including PE, PP, PC, PET, PVC, Epoxies, Teflon and other flouropolymers (in modest quantities–the Florine’s pretty rare). Just no silicones unless you bring your own Si
  • Carbon and aramid fibers
  • Graphite, Graphene, and Carbon Nanotubes
  • Sulfur “Concrete” (likely using graphite whiskers as the reinforcement)

Anything metal would likely need to be imported, but if the ISRU equipment to get to simple polymers and carbon fibers isn’t prohibitively large, you might actually be able to build most of the structures, the sulfuric-acid resistant outer skin, and the breathable atmosphere, and drinking water all from local materials. Seems promising.

Next Up: Condenseables

Posted in ISRU, Space Development, Space Settlement, Venus | 54 Comments