Category Archives: Exploration

Mars Colony Design Update

While it was an honor to get to the top ten finalists out of one hundred entries, I did not get into the top five winners.    I don't think this is the time or place to get into why the judging took place the way it did, simply because I wasn't there for it.  What I will do is defend my thesis and purpose in the decisions I made with the Eureka design, and elaborate on the answers I gave the judges at the time.   As far as making up your own mind, the top 25 semifinalists will be published in a book next month.  So future mars colonists will be able to review our work. 

Pu​rpose

There were a number of hard questions meant to give a more complete picture of the settlement in the contest criteria.  You had to come up with the structure, then an economic model, then a political model, aesthetics, and culture.   I went well beyond this into the very toughest challenges to space settlement where Mars is concerned and took them all head on.  Everyone else was running a marathon, but I was running an obstacle course for the duration of the marathon.  

Here's the thing.  I've been working on parts of the problem for over a decade.  I had focused on the worst issues I could find, because I know that there are not good answers in a lot of those spaces.  No one had a complete solution that was designed to be complete and unassailable to the critics and possible risks of a settlement on Mars.  I decided to try for that.  Even if it fell short, it would show what the hardest issues were left to solve so that I could focus on those.  But as it turned out, I answered all my challenges and offered root cause analysis back to the origins of civilization as to why those solutions were chosen. 

The Greenhouses

Robert Zubrin asked about the power requirements for the greenhouses, and has stated in the past that he felt greenhouses on mars should be naturally lit.  I did not have an answer for him off the bat because I had realized that power was not a forcing function last winter with my design.  The forcing function was surface area per person for food growth.  The best shape for a pressure vessel is a sphere.  A flat greenhouse, even under partial pressure, is a nightmare in terms of structural needs, materials needed for transport to Mars, and so on.  It is wide open to meteor strikes or possible attacks by rival powers.  There is the possibility that a key crop is too sensitive to radiation to be reliably used as food after being grown with such exposure.  I chose a heavily shielded stacked LED lit greenhouse because this gave easy temperature control, 24 hour daylight where appropriate, radiation protection to the harvesters, meteorite protection, and restricted exposure to epigenetic crop stress.  In the rotating ring, I also had 1G gardens where that was potentially appropriate.  We cannot just assume that all plants we want or need will grow in a Mars greenhouse, or that building them would be a good idea.  As for the power question, when the population hits 1200 people, the power demand is 275 megawatts.  At 40 MT per 2 megawatt reactor, this calls for larger reactors for better economies of scale. The concept called for every sixth starship to be carrying a nuclear power plant with a six megawatt output.  My forcing function was volume, followed by reactor transportation, followed by reactor cost.   Natural light would not reach the inside of a stacked plant bed like that used in an LED greenhouse.  With Mars frequent dust storms, you would need a reactor-fed LED light system anyway in addition to all your glass.  So why bother making more failure points?
Anyway, I had to get that off my chest. 

Conclusion

 The Mars Society is now saying they want to sponsor a million person Mars city proposal.  At the moment, I'm not considering making an entry.  I put off a number of projects to do the work I did on the Mars Settlement design.  I'm unwilling to keep putting off life goals for things like this after having sunk a very critical, pivotal year into this one.   The lasting good effects of having a bulletproof (literally) Mars settlement design are just beginning.  Eureka may be the winner in the long run after all. 

Yet Another BFS Set of Changes from SpaceX – Some Speculation

UPDATES (12/9/2018):

The basic layout of the ship will remain the same. So most of the speculation below is off.  However, some issues, such as where the solar arrays will be stowed, are still open for interpretation.

Material Change to Vehicle

The main change is that they are shifting from a very high tech composite to a “fairly heavy metal”.  The lightest metal routinely used in spacecraft engineering at scale is an aluminium/lithium alloy that was used for the Space Shuttle external tank.  An unlikely option is something with a thin layer of stainless steel, which would be necessary for a reusable vehicle using liquid hydrogen.  That said, bear in mind that the initial flights to Mars may need liquid hydrogen in reserve (rather than drilling for water) because the reserves of water would have yet to be proven on Mars.  This was actually a key design detail of Mars Direct, which was designed before glaciers were observed below the dust in middle latitudes.  These glaciers are ideal for providing propellant, but it would take a crew to set up a proper drilling rig and return the melted water to the surface for processing.  The first ships will not have crews, meaning that either they have to take a fairly hard risk and build the propellant plant on the first crewed mission or die on Mars, or they have to have a backup plan like a hydrogen tank.  A lot has to go right on the first two missions to get that infrastructure in place.  That said, there would be no shortage of volunteers.

Schedule Updates

They also announced that we will be seeing “cool pictures of the demo Starship that will fly suborbital hops in the coming (roughly) 4 weeks.”  Four weeks out from the announcement date would be January 5, 2019.

SpaceX applied for a license to test the “up and down hopper” version of Starship in Texas.  They will initially do short tests up to 500 meters/100 seconds.  They will then extend to 5 km flights up to 6 minutes.  They are also finalizing construction of the test facility/launch facility with a large tent, fuel tanks, antennas, and moving a lot of dirt around to make causeways across the soft sandy ground.

(Original Article below).

Recently, Elon Musk mentioned that the new spacecraft in development, known originally as Mars Colonial Transport, then Interplanetary Transport System, then BFS, is now being called simply “Starship”.  The booster is now also simplified from BFR to “Super Heavy”.  This makes some sense in that his satellite constellation is being called Starlink.  This seems to go back to calling the space-suited mannequin on the Falcon Heavy test launch “Starman” after the David Bowie song.  It wouldn’t be the first time – Dragon is named after Puff the Magic Dragon, and Falcon after the Millennium Falcon from Star Wars.  The two drone ships are named after sentient starships from a science fiction book series.  There are also lots of Hitchhikers Guide to the Galaxy references in his nomenclature.

He has also indicated that he recently-announced Hello Moon version of the Starship design is being changed yet again.  The new change would be counter-intuitive, and when asked, he simply said, “RADICAL CHANGE”.  He also said the new design is exciting and delightfully counter-intuitive.  Note that he also said the Hello Moon design was counter intuitive due to the front and rear fins rotating in terms of lateral drag but appearing superficially like forward control surfaces.

Keep in mind that Blue Origin has second mover advantage here.  Whatever SpaceX settles on for a design, Blue Origin can come up with something similar or better with New Armstrong.  Constantly changing the design in radical ways will tend to kill that second mover advantage for Blue Origin in terms of years of lead time.  If SpaceX had stuck with their original design, Blue Origin would be studying it extensively and have a three year lead time in coming up with something better.  As of now, they are just as lost as we are.  That may also be part of the purpose of the ever-changing design, and some of the Issues mentioned below.

Analysis of Issues

Here are the key issues I’ve noticed with Starship’s design…

No escape system – It is designed like an airliner, but with no escape system for ground evacuation or launch escape.

Solar Panels – Most recent versions do not seem to have a place to stow solar panels.  The ones protruding from the initial design could have been stowed in the tri-form fin-like elements, but the past few ships show nothing but tanks in the rear sections. This implies some sort of lateral spine or (in the Hello Moon version) a place to put much smaller panels in the tail-fin.

Center of Gravity/Center of Pressure on Landing – The Falcon boosters can land tail-first in part because all the engine weight is in the tail.  They basically land like lawn darts.  A Starship will launch with a heavy nose, fuel tanks, and a heavy tail with the engines.  After using up the fuel supply from launch, there is still weight in the nose and tail, averaging out the center of gravity.  That said, the rear fins went from protrusions to a small delta control surface to a full pair of fins because the side-facing atmospheric entry would make it difficult with so much mass in the tail to keep the vehicle stable.

Unloading on the Moon/Mars – Depictions show a door opening out of the cargo bay side with a crane lowering components to the surface.  This would work with some elements, but may be difficult with large equipment.  It would also be very difficult with passengers in mass or any sort of emergency landing with a point-to-point flight on Earth.  Unloading like this with heavy gear may actually risk tipping the ship over, especially if it were landed on any slope toward the cargo door or an unsteady surface.

Engine Plume Hammering on Unprepared Surfaces – One key reason that NASA resorted to the extreme measure of landing the Curiosity rover using a skycrane was that engines big enough to land a one ton rover could easily drill the lander into the surface by way of the extreme supersonic exhaust plumes of the rocket engines being so close to the surface.  The Apollo LEM dealt with this by using a wide engine bell, low impulse propellants, and cutting the engine about a meter in the air and then dropping down to the surface.  Existing Mars landers typically use a cluster of tiny rockets in pods on the side to spread out the exhaust plume, and also use low impulse propellants.  SpaceX is using fairly high performance engines, and sea level ones in the case of the Hello Moon version, for landings.  On Earth, landing on a concrete pad solves the problem for the most part – the surface is strong enough to support the lander on a level surface, and also to take the force of engines blasting it with hypersonic, superheated propellant.  Unprepared surfaces would have to be very level bedrock outcroppings.

That Massive Window – This would be heavy, fragile, expensive, and deeply impractical from a structural prospective.  The only aircraft I’ve ever seen with a cockpit like this is the US B-36 bomber.  While the second version of Starship lacked this window, the Hello Moon version brought it back again.

Possible Options

So what does that mean?  SpaceX must be aware of all the issues listed above. Here are some speculations off the top of my head – some wild, some pragmatic.  The wilder ones are simply in response to how loaded that announcement was in terms of language.

Canard Changes?  Given the purpose of the canard wings on the Starship, it seems logical to change the arrangement from rear-swept to forward-swept to decrease drag and increase “reach” for the movement arm of the control surface.  If the lateral engine nacelles were used as noted above, a second set of downward-angled control surfaces could be on the back side.

Move the Solar Panels up to the Cargo Bay?  This has a lot of potential.  They wouldn’t be subject to the stress of being so close to the engines on take-off.  They would also be more accessible by the crew in the event of a deployment or stowing error. On the surface of the moon or Mars, they would be up and away from the dust and surface operations close to the vehicle. This wouldn’t be a radical change, but it’s got some practical benefits.  They could also be more practically scaled to the mission by being larger for deep space, or possibly replaced entirely with a low-enriched uranium reactor like KiloPower.

Detachable Payload/Crew Section?  This also has potential for Lunar and Mars operations.  One benefit of Mars Direct is that the Earth Return Vehicle (filled with propellant) is stored a safe distance from the crew habitat.  By recombining the two (the very first concept that lead to Mars Direct was a single vehicle like Starship), SpaceX adds this risk.

Also, habitats can be left behind or used as space stations, particularly if they have their own solar power supply as mentioned above. Note that the current Starship design has more cubic meters of pressurized volume than the entire International Space Station.  It simply lacks docking ports and would need a much larger solar array. A detachable payload section would have both. At any rate, ISS replacement could simply be a crew module with a solar array, coupled to a power/propulsion/docking Service Module on a second flight.  The Service Module would also have a lot of potential working in series for space factories, solar propulsion systems, and fuel depots. It would basically eat the entire Blue Origin and ULA long term road map in one swift stroke.

This would also add some capacity for crew escape, even if it’s a passive detachment with parachutes or landing rockets.

Lateral Engines?  This is pretty interesting.  The Skylon design has engines on the side because it was derived from the HOTOL concept from a couple decades earlier.  HOTOL would have been a European space shuttle, and used a very heavy engine arrangement at the rear.  However, the center of gravity would have shifted too far back to be stable after fuel burn.  This is also a problem with Starship, and had lead to the ever-increasing wing size at the tail.  Having the small landing engines on nacelles off the side of the vehicle would deal with landing on unprepared surfaces.  It would also give an option for crew escape if coupled with the smaller propellant tanks used for landing in the original design. It may allow for cargo at the rear end if all the engines were put on pylons.  It would remove some of the need for the rear wing, which may be difficult to engineer due to the stress on the hinge and electric motors.  It would give a deployment platform for a crane and a counter-weight for laterally unloading payloads. It may have also led to the name change.  After all, nacelles are a design hallmark of the Enterprise and Firefly’s Serenity.  Elon also doesn’t design anything unless it looks better than Hollywood could design.  This could be a pretty elegant design when he gets through with it.  With such inspirations as Serenity and Enterprise, not to mention the Star Wars Y-Wing, that could be the inspiration for the name change as well.  It certainly would look like a starship in the popular imagination. The disadvantage would be drag on takeoff from Earth, but it would allow for retractable landing gear that could be scaled to the engine arrangement and destination. I can call this neither probable or improbable, but simply file it under, “I wouldn’t put it past them”.

Payload section at the back?  While this would solve the load/unload issue, it would make crew escape much worse. It would also make center of gravity far worse, as well as subjecting the crew/payload to intense vibration.  This is not entirely unlike the back of the Shuttle cargo bay being close to the engines, but it seems incredibly unlikely. It would also be relatively ugly on the interior, since putting windows that close to the compression between the tanks and the engines would be suicidal.  For these reasons, I’d say no.  Though a variant of it is already in place with the tail-end cargo pods for the Hello Moon version.  I cannot see them doing more than that.  Then again, if they put all the engines in nacelles and not just the landing ones, this may make more sense.  The cabin could simply drop down to the surface.

Split Payload Transformer?  Imagine a ship with a payload nose section that splits in two.  Each section could be lowered to the ground for easy access.  The side with the crew/passengers would also have an escape system.  It could also be split into more than two sections, provided they had some symmetry.  They could even be spun for low-level artificial gravity. This seems highly unlikely, because having multiple pressurized bays becomes incredibly heavy for no practical benefit.  I’d say unlikely for this reason.  Elon Musk loves platonic ideals, not complexity for its own sake.

Conclusion

This rather extensive and somewhat wild flight of imagination is the sort of thing one pictures when Elon Musk says, “radical change” and “delightfully counter-intuitive”.  I suspect it will solve some of the issues noted above, because they would need some dramatic reason to change the design at this stage.  Elon Musk likes idealized solutions with minimal draw-backs, and tends to iterate towards a democratized, ubiquitous product line rather than away from it.  I may have hit on some of it with the more likely options.

Knowing SpaceX, I’m looking forward to being proven wrong in some delightfully clever way.









Speaking in August at the 20th Mars Society Conference

I will be speaking at the August 23-26 Mars Society Conference at the Pasadena Convention Center.   This year will be another wonderful, informative convention with a new emphasis on VR projects we are currently getting ready to deliver for use at MDRS and eventually for Mars itself. We also have another university competition to design a heavy lander for Mars.

If you can’t attend the convention, I release the slides to this web site along with links to YouTube when The Mars Society puts those together a couple months later.

Planetary Protection and Settlement

On Thursday in the Science Track room at 1:00 PM, I’ll be speaking about finding ways for planetary settlement to work if and when life is found on another world.  This is actually highly likely given the amount of bacteria ejected into space from meteors colliding with Earth in the early days of the solar system after bacteria had already formed.  The issue is how to find a happy medium where we inhabit other worlds but we keep the existing biomes and our own habitats from interacting accidentally.

SpaceX, Methodologies, and Predictions

On Friday, I’ll be speaking at 2:30 in Room 214 on SpaceX and how the NewSpace companies are accelerating so quickly over their Legacy Space counterparts.  I’ll also forecast how some of these efforts will turn out based on past performance and current conditions.  Want a realistic estimate on when and where you will be able to fly around the Earth in a BFR for a family vacation?

 









A Little Mars Society/Robotics Update

Occasionally, I bump into people who are both interesting and who are interested some of the stuff I’ve described in conversation.  So some of these posts are basically for an audience of one in inspiration, but are probably of enough interest that anyone else who likes this site would enjoy them as well.  So anyway, Mike from the fly in breakfast this morning – this is for you.

I’m the Steering Committee Chair of The Mars Society. Our convention is coming up in Pasadena this August.  My abstracts for this coming year will involve reverse engineering how SpaceX does so much R&D so fast, and why Elon Musk is so “bad” at making predictions about when his rockets will be ready for launch.  The other talk is more of a handbook for preserving science while settling Mars and other places that may have native life, essentially by putting up a “dingo fence” at the microbial level between what humans do and what anything local may do.

You will soon be able to visit Mars Desert Research Station in VR if you have the headset, as well as explore roughly a square mile around the habitat.  You can do something similar right now with 360 views of the various facilities that are online for free just using your web browser.

The Mars Society runs an annual event called The University Rover Challenge.  Teams from universities all over the world compete with robots they have built to do various tasks in the Utah desert around MDRS. These competitors have gone from simple remote control carts to elaborate rovers worthy of any space agency.  Interestingly, Poland’s universities have a tendency to win this thing regularly.

Above is my “Hero shot” from my first trip to MDRS, over 14 years ago now.  Those are the first generation, custom made suits we had that were designed to be like the Apollo moon suits.  Yes, it really looks that much like Mars out there.  The geology is analogous as well, which is why we do so much Mars research out there for not only NASA, but many universities and other organizations.









Slight Update on BFR

SpaceX president Gwynne Shotwell recently did a TED talk that included a slide showing three designs for the BFR.  The original from 2016 is on the far right of this image, and is the largest and oldest concept.  In 2017, the design was revised to be smaller and far easier to build.  This version can also do airline service anywhere in the world near an ocean in less than 45 minutes. 

What is noteworthy is the middle version.  This is simply dated 2018, and shows a length almost exactly half-way between the original 12 meter diameter vehicle and the revised 9 meter diameter. This seems to be due to refinement of the aerodynamic design of the nose and wing surfaces.  The wing roots are much longer along the side of the fuselage, although that seems to be partially due to the slightly different angle in the renderings. 

Also included this time are four small landing legs, which protrude past the booster BFR stage.  They simply do not appear in last year's version.  In the original, there are three retractable legs in fairings, two of which are part of the entry shield.  

New BFR for 2018

New BFR for 2018

Legs and Engine Concerns

The engines in the original design protruded past the back of the fuselage in the original design.  In the 2017 revision, the engines are completely covered by the aft fuselage skirt.  It is possible that the extended landing legs allow for the engines to protrude slightly again.  It may also be a consolidation to landing on Mars or other unprepared surfaces like the moon.  There are two great fears in landing on unprepared surfaces with rockets, such as the moon and Mars.  One is that rocks can be kicked up by the exhaust and damage the engine bell.  This did happen with one of the Apollo landings.  While Apollo used a different engine to return to space, the BFS is stuck with the same exposed engines for ascent.  The second factor is that these engines are basically blow-torches that put out exhaust at hypersonic speeds.  As such, they can take the dirt of the moon or Mars and essentially stir it like liquid while landing.  After landing, the unsettled dirt can settle around the foot-pads, essentially burying them under the surface.  This is one of the reasons the Curiosity lander used a jet-pack on a tether to lower the rover to the surface - to keep those engines as far away from the ground as possible.   While less of an issue for lunar landing due to lower thrust requirements, it may be an issue for Mars.  In both cases, getting landing pads built will be a very early priority to avoid throwing rocks at whatever you had landed prior to that point. Early landings may avoid the issue by landing in craters. 

The four leg configuration also means another slight design difference from last year.  Since the legs protrude, the back-to-back configuration for one vehicle to refuel another on orbit will have to be done at a slight angle to allow the legs of each vehicle to slide past each other.  

Capacity Issues

The configuration changes imply they have stretched the propellant tanks slightly in the new design.  This would be good, as the reduction in diameter between 2016's twelve meter diameter and 2017's nine meter diameter, all else being equivalent, reduces both the propellant and pressurized crew compartment volumes by 70 percent.  The revised design slides form 2017 show only a 43 percent reduction in propellant load by mass, however. The revised design is much longer than a 25 percent reduction in length, and the propellant tanks appear to be more efficiently designed in terms of capacity than the 2016 design.  A recent photo analysis of the machine used to make the fuel tanks of both stages shows that the interior diameter is slightly over nine meters, instead of the exterior as originally expected.  Due to economies of scale, every little addition to the tank volume dimensions has a substantial impact on payload.   The 2017 design also mentioned 40 crew cabins, as opposed to the original crew of 100 people.  While you may well have two to a cabin, the substantial reduction in volume would make things cozier.  

Next Steps

SpaceX is also leasing an older large building with an adjoining dock in Los Angeles, California to build the BFR.  Tooling is already being delivered to the site. (Don't get too excited about the photo that appears to show the nose fabrication machine - that's actually a Boeing 787 machine that would be very similar to it.) 

While Elon Musk wants BFR going to Mars robotically in 2022 and with a crew in 2024, Gwynne sees humans on mars by 2028 as a "for sure" outcome.  Near term projects mostly involve short vertical hops, with longer term work on flying up, then using the engines and remaining fuel to slam into the atmosphere to simulate reentry from deep space.  This is very critical.  Vehicles arriving at these speeds heat up with the cube of velocity, so little changes in speed can make the entry fatal. This, in turn, dictates not only the flight time to and from Mars, but the payload capacity allowed for both flights.  









Low-Thrust Breakthrough Propulsion Round-Up

Next Big Future has produced a number of articles recently on breakthrough propulsion.  Here is a summary of the current state of the art on these speculative systems.

Low-Thrust Propulsion systems are too weak to be used to launch from the surface of a planet, but have extreme efficiency and high exhaust velocities.  Basically, a space probe like Dawn had the propulsive force equivalent two sheets of paper held on your hand.  Yet it could thrust for years with this system.  Over the course of eight years, it thrust over 2000 days, with a change in velocity of 24,000 mph/ 38,000 kph.  That's more than it took to launch it into interplanetary space to begin with, and while using less than 937 pounds/425 kg of propellant on board.  Ion drive takes a slowly-released gas, gives it an electrostatic charge, and then accelerates it in a magnetic field and neutralizes the charge as it exits the engine.  Newer systems, such as the speculative EM-Drive, promise to work with no on-board propellant. 

While creating full-antimatter is very, very difficult and energy-intensive, making simple positrons (antimatter electrons) is fairly simple.  A group is working on a system that can fit on a cubesat for a demonstrator.  Rather than make full anti-matter atoms and trying to store them and use them later in an engine, a positon system is basically an ion drive system like Dawn uses, but using positrons made on the ship itself instead of ionized gas.  Positrons are naturally produced by radioactive materials.  So a sample of a radioisotope is placed on board, and the positrons it emits are cooled enough to allow them to be directed and accelerated in a magnetic field like in a conventional ion drive.  The resulting particles exit the vehicle at ten percent the speed of light.  If idealized, these systems could get to Mars in weeks, Pluto in months, and Alpha Centauri in 40 years.   The developer, Positron Dynamics, plans to launch a cubesat demonstrator somewhere between the middle of this year and next year.  The near term application of these motors would be as a more-efficient substitute for ion drive in positioning communications satellites.  In the longer term, they would be very useful for asteroid mining.  

To make a complex system a bit easier to understand, a small fuel pellet is compressed by a magnetic field and bombarded with particles.  It undergoes nuclear fission and the plasma is further compressed by the magnetic field.  The combination of compression and the heat, self-generated plasma magnetic field, and particle mix of the tiny fission explosion can trigger a fusion explosion, similar to the way an atomic bomb can trigger a thermonuclear (fusion) bomb.   As with the Positron example, this could theoretically get a vessel to Mars in a month.  It would generate exhaust ISP(the efficiency of a rocket)  of 30,000 seconds.   By contrast, a typical chemical rocket has an ISP under 450 seconds. 

This is similar to  EM drive, in that it depends on A) very tiny effects that can barely be observed and B) processes that defy conventional physics, but appear to be explained by some aspects of science.  When I say barely observable, we are talking 2 to 12 micronewtons.  A tiny bottle-rocket has 3 newtons of average thrust, or a million times as much as these experimental engines.  That said, they hope to get up to 10-20 millinewtons in a decade or two.  That said, a microthrust, propellantless system has no theoretical output limit, because there is no propellant to be used up.  This is why those who propose systems like this often speak of starships. 

Conclusions

The positron system seems quite logical, and can be demonstrated soon.  It has limits, though, because it relies on radioactive decay of highly radioactive materials.  This can be scaled down into tiny systems.   The PuFF system will require a lot of expensive research to get worked out, over a fairly long time period.  That said, it has a lot of similarities to Project Daedalus, and could be used for a simple starship probe eventually.  Such a system is at least a decade away, and would be quite large.  Mach Effect is a lot like EM Drive, but while the effects are more explainable, they seem to be even less powerful.   To power a vehicle with any velocity, it also has to be scaled up quite a bit.  
With new systems that can provide fission and possibly fusion electrical power coming online very shortly, systems that require lots of electricity (advanced ion drive, these propellantless systems, and so on) may be arriving sooner rather than later.  Expect to see something interesting in this range within five to ten years.  









Old Space Station, NewSpace Station

There has been much said of the recent budget proposal, that zeros out funding for the International Space Station in the year 2025.  What never seems to be mentioned is that the ISS was due to be retired in 2024.  This is already a four year extension over the original retirement date of 2020.  The station costs a sizable portion of NASA's budget to operate, and may not be sustainable from a structural standpoint after the year 2028.  The ISS has a pressurized volume of 388 cubic meters, and cost $100 billion to construct. 

Bigelow Areospace originally planned to have two of its BA330 modules ready to launch by 2017.  These modules have 330 cubic meters of habitable volume - almost equal to the entire ISS.  Note that the power input from the BA330 solar panels is much lower, so such a new station would not have the same capacity to run experiments.  The ISS has solar arrays the size of an American football field, and generate 84-120 kilowatts. The BA330 power levels are not yet published, but the solar arrays are far smaller.

Bigelow already has a small prototype, called BEAM, attached to the ISS.  This is giving NASA experience with the technology and allows the crews on ISS to experiment with this new inflatable habitat system.  Bigelow is now proposing a new module, a full BA330, to be attached to ISS.  This module is called XBASE.  This could be ready by 2021, although it may be delayed due to the requirement to launch on the as-yet-undeveloped ULA Vulcan launch vehicle.  

Analysis

ISS was built with parts that are no longer in production.  Much like the Space Shuttle before it, the cost of maintaining a system with limited spare parts becomes prohibitive with time.  Also, without the Space Shuttle, large modules cannot be returned to earth to be rebuilt and relaunched. Similarly, the spacesuits on the US side needed to maintain ISS are in many cases leftover from the Shuttle era.  They are far beyond their designed lifespan and are having age-related and design flaw-related issues.  Extending the life of the ISS beyond 2024 becomes more of a risk with each passing year, and the costs will increase as parts become harder to come by.  A key strength of the ISS, the vast solar power system, must run on batteries 45 percent of the time as the station goes into the shadow of the earth on each orbit.  Those batteries also have a finite lifespan. 

We are in a race to build a new system before the old system is retired.  We failed to do this with the Space Shuttle, as several proposed replacements were cancelled prior to retirement of the shuttle.  We also need new spacesuits sooner rather than later.  The XBASE proposal could be launched as an adjunct to the old space station.  This would give the new station access to power and more extensive facilities, while still being a brand new facility.  Not everything on board the ISS is completely worn out.  Some facilities are a decade newer than others.  It may be possible to move some systems over to the Bigelow module to extend their operational lives.  It may also be possible to use the XBASE as a primary facility while maintaining some experiments on the old ISS indefinitely.  ISS already does this to some degree - the original Russian module was the habitat, propulsion, and power system for the ISS in the early stages of construction.  Now, it is primarily just a hallway connecting newer Russian modules on one side with newer US/EU/Japan modules on the other.  

A system with ISS and XBASE combined, with the later addition of one or two more Bigelow habitats, would give a graceful exit to the ISS facility and offer a new platform for life support, habitation, and more modern experiments.  As systems on ISS wore out or were no longer maintainable, they could be shut down and bypassed.  When the overall cost to benefit ratio of the system exceeds practicality, we can simply separate the facilities and send ISS to the bottom of the Pacific as originally intended.  

Having BA330 dependent on Vulcan appears to be a mistake.  Perhaps they can launch something on the Falcon Heavy on a shorter time frame if Vulcan is delayed.  Since all new rocket projects are delayed, that seems a solid bet.  The default Falcon fairing is far too small for BA330, but the payload capacity in terms of mass is far better than Vulcan.  It should be possible to equip a Falcon Heavy with an oversized fairing for the mission, provided the aerodynamics and weight/balance issues can be settled. 









Videos and slides added from my Mars Society talks at Irvine, CA

Video of my talks at UC Irvine for the Mars Society are now available on YouTube.  The slides are in the description and in the comments thread on those YouTube links. 
For a list of all videos available, see the Videos and Other Content page. 

Risk Reduction Missions for Space Settlement


While the early stages of the NewSpace revolution are in place, what projects could be done to expand human activity into deep space as soon as possible, with minimal cost and risk?  This talk examines a few options that could be launched in the next few years. 

PDF of Presentation

Rapid Space Development and the NewSpace Technology Revolution

This presentation examines the nature of technology revolutions, and the nature of the next revolution in space technology.  It goes on to predict the nature of our expansion into the solar system, using principles from past technology revolutions. 

PDF of Presentation









Elon Musk on Reddit AMA

Elon Musk recently did a Reddit Q&A with members (Ask Me Anything).   This mostly focuses on details of the Mars vehicle update.  Here are some highlights.

Mars Settlement

  • The Mars city design from the video was mostly artistic (“I wouldn’t read too much into that illustration”.  There are no specific plans beyond propellant production, power, and life support.  He wants to enable other industries to go to Mars.
  • The landing sites need to be low altitude for maximum aerobraking.  Close to ice for propellant production and free of giant boulders.  Closer to equator is better for solar power.
  • SpaceX is building the ISRU (propellant production system) in house, and it’s pretty far along.
  • They plan to put communications satellites around Mars at some point.

Technical Details of the BFR and Spaceship

  • The vehicle would burn all the fuel in the main tanks getting to Mars (or the moon or Singapore or whatever).  It would then use the secondary tanks for landing.  In the case of Mars, it would turn the nose of the ship toward the sun and vent the outer tanks.  This would basically make the inner tanks super-cold for the trip.  (Editor note – it would also eliminate the possibility of spinning two spacecraft with a tether for artificial gravity).
    • They eventually will add a cryocooler (which would allow it to spin).
  • The newest Raptor engines being tested are actually sub-scale.  The final production version is being designed for reliability, not performance.
  • the small delta wing is to “balance out” the load on reentry, to keep the ship from entering engines-first.  It can also provide some pitch and yaw control during reentry.
  • The RCS system will be methane/oxygen and pressure fed.
  • Early versions of the tanker will be just a fully-loaded propellant tank ship with no payload.  Later versions will look “kinda weird”.
  • Heat shield tanks are mounted directly to the tank walls.
  • The development will start with a full-scale ship doing short hops of a few hundred kilometers up and across.  They don’t need the deep-space Raptor engines for that.
  • VERY INTERESTING – “Worth noting that BFS is capable of reaching orbit by itself with low payload, but having the BF Booster increases payload by more than an order of magnitude. Earth is the wrong planet for single stage to orbit. No problemo on Mars.”
    • Traditionally, methane doesn’t have the specific impulse to do single stage to orbit.
    • A BFS without the booster would be economical for domestic flights, in theory. They could also return themselves from interior destinations like Chicago to coastal launch facilities with the BFR stage.

Anyway, you can read it in detail if you like from the link above.  I simply gleaned what I could from the stream in the notes here.