The ISS as fuel depot testbed

I've been wondering for some time if the ISS could be used to advance the technology required to perfect propellant depot technology. It seems that nearly all of the required hardware is already on board the station. The current ECLSS on the ISS electrolyze waste water and condensate to generate breathable oxygen, with the excess hydrogen being vented to space. If the hydrogen stream could be diverted into a Sabatier reactor, then CO₂ could be scrubbed from the atmosphere and turned into methane fuel.

I've also been wondering for if a propellant depot infrastructure should be resupplied with pure water rather than the cryogenic fluids. The favorable density and handling properties of water as opposed to LO2/LH2 would appear to make it the better choice for transporting aboard a very simple tanker over potentially long time periods. When shipped as water, the "fuel" can be transported in a non-cryogenic, inert state, and then once delivered to the depot, it can be cracked into O2/H2, liquefied, and stored until it is needed.

Of course, this assumes that your depot has sufficient power and/or time to split water and keep the fuel properly chilled. I found this page which describes the Russian Elektron unit. This article cites a passage from a NASA training manual:

NASA TRAINING MANUAL ON ‘ELEKTRON’

From the “NASA Familiarization Manual on Russian Segment Crew Systems”, Published in 1997.

3.1. Oxygen Supply System
...
The decomposition of 1 kg (2.2 lbs) of water yields 25 L (0.88 ft3) of oxygen per hour at a pressure of 760 mmHg, which is enough to support one crew member for one day. To provide the daily amount of oxygen for 3 - 4 crew members, 3 - 4 kg (6.6 - 8.8 lbs) of water must be decomposed. Power consumption of the process is ~ 1 kW.

A kilogram per hour at one kW, seems like a very reasonable rate, at that's just for one Elektron unit (if I'm reading this correctly). If necessary, this can scaled up with additional units if sufficient power is available. It may be possible to build even more power efficient electrolysis system if the work of Dr. Nocera at MIT can be turned into a practical device that will operate in zero-G conditions.

If the depot is also crewed, then a steady supply of water would be required any way. The crewed depot could also generate methane as an additional propellant option if the ECLSS included a Sabatier reactor as well as an electrolysis unit. With the exception of the Sabatier reactor and some cryogenic storage tanks, the ISS already possesses all of the hardware. The existing U.S. electrolysis units even have hardware available for connecting to a Sabatier reactor.

So, what would be the point of having the ISS generate and store propellant? Well, first of all, it is currently our only manned research outpost in zero-G. It would therefore be expedient to take advantage of these facilities to work out the basics of cryogenic fluid transfer in micro-gravity. The data obtained from ISS experiments could go along way towards reducing the techological risks associated with propellant depot development.

The ISS also needs fuel for station-keeping. Having the ability to generate it's own propellant would be a nice capability to have. This would also simplify the ISS resupply requirements. Rather than having to deliver water and propellant, each in the individual compartments, only water would be required. The water tanks could be made larger, and therefore more mass efficient. Since propellants would no longer need to be transported (I think hypergolics are currently used), the handling of the payload for resupply missions would be much less hazardous.

Finally, with the ability to produce fuel, the ISS could support a small array of space tugs and transfer vehicles which would service the station and other objects in nearby orbits. For example, imagine that SpaceX puts up a couple of Dragon lab modules in orbits which are coplanar with the ISS. Now imagine that the ISS has a slightly modified ATV docked to it. It might then be possible for an ISS astronaut to use the ATV to rendezvous with the Dragon module and perform any necessary maintenance or repairs.

I have some additional thoughts on how to convert the ATV into a crewed orbital transfer vehicle, but I think I'll save those for another post.

ISDC 2007 - Day One

Well, I figure I should report my impressions of day one at the International Space Development Conference before I read any one else's , and while it's still somewhat fresh in my mind.

First of all, I have a little gripe. The traffic in and around Dallas is a nightmare. I don't know how it stacks up against other major metropolitan areas, but I've been stuck in Dallas traffic for a total of five hours now, and I've only been here two days. From what I'm beginning to learn from some locals is that the conference location at the Hotel Intercontinental could not be in a worse location as far as commuting goes. Hopefully the weekend traffic will be more merciful, although I'm skeptical since it is Memorial Day weekend.

I did get to see Shannon Lucid and Don Pettit give their presentation in the morning. During and after the lunch break I spent some time talking with folks in the halls and at the displays. This is the first ISDC I have attended, and really my first space related conference. So, it was fun talking to other people who are as passionate about space as I am.

The presentation by Drs. Lucid and Pettit was mostly about the mindset of living and working on the frontier. As both of them have been on long duration missions (six months on Mir for Dr. Lucid, and six months on ISS for Dr. Pettit), they have a unique perspective on life on the new frontier. Dr. Pettit has also recently taken part in a trek across Antarctica looking for meteorites; a journey which he paralleled with his stay on the ISS.

The pair discussed many different aspects of frontier life, but the one I was most interested in was the science of opportunity discussed by Dr. Pettit. He described the ISS and Antarctica as non-intuitive environments: places where everyday can bring new and unexpected experiences. In these environments, discoveries are just waiting to be made.

I wish he would have spent more time talking about those moments of discovery. In my opinion, this is one of the most important reasons why we are sending people into space. Most of the low-hanging fruit, in terms of scientific discovery, have been picked. To make new discoveries, someone has to study new phenomena, or possibly even well known phenomena in new environments. On Earth, this requires spending increasing large amounts to create these new environments in particle accelerators. However, their are many things about the universe that we take for granted just simply because we experience them every day. These things become part of our intuition and typically get pushed to the back of minds. By experiencing the non-intuitive environments, as Dr. Pettit describes, "...we can become children again, and experience the world with a child's curiosity". (quote paraphrased)

After lunch, I got to spend some time talking with James Bauer of Armadillo Aerospace. It is truly amazing what this small group has been able to accomplish. I can't help but think of Steve Wozniack hacking together the first Apple computers in his garage and the effect that effort had on the world of computing. I think that John Carmack and his team are poised to do the same thing for the world of rocketry.

Yes, Pixel was on display, and I got to tell you that this is an impressive machine. It's impressive mostly because it looks so simple. I've been to several Air & Space museums and have seen some of the rocket engines developed by and for NASA. Those things are a maze of wires and tubes and components. I think you really have to know what you are looking at to truly appreciate their design. However, Pixel is the very model of simplicity. I'm not trying to trivialize their work. I think the simplicity of their design is brilliant. Less parts means less things that could fail, which means (or could mean) greater reliability. It also means that they are cheaper and easier to build than your typical rocket engine; a feature the they intend to capitalize on as they move towards building their modular rocket design.

I also had the opportunity to talk with Tom Ligon of Energy Matter Conversion Corporation (EMC²). I've got to say that the system he is describing seems almost too good to be true. He claims that the power output of the fusor reactor scales with the seventh power of reactor radius. I asked him if there were any upper limits to this scaling. He replied that Dr. Bussard has thus far only considered reactor designs up to 6 meters in diameter. That is an enormous amount of energy. We're talking about 6 GW out of a roughly 6 meter diameter reactor (if I'm remembering correctly), and the output goes straight to DC; no more heat water turn turbine.

When someone makes that kind of prediction and only has preliminary experimental data to back it up, I can understand why it would meet with some skepticism. Still, if they are successful, this technology could literally change the world. Given that potential, I don't see why they would have any difficulty raising a couple of hundred million dollars they need to definitively establish its viability. But that's just it. I get the sense that the effort is strapped for cash. I have seen bigger grants awarded to academic institutions to conduct basic research. So, I can't help but think that there may be other factors at work behind the scenes.

Anyway, that's all for now. I try to post more in the next couple of days as I have time.

Mars Rovers on the Futures Channel

Just got an email update from the Futures Channel. They have a new short film up on the Mars Rovers.

http://www.thefutureschannel.com/dockets/hands-on_math/reliable_robots/index.php

Two of the engineers who work on designing robotic rovers discuss what it takes to make a robotic system which is reliable and robust enough to send to the most remote destinations. If any one part of it fails, the rest of the systems should still be able to carry on in some fashion to complete the mission.

While it's true that if something goes wrong there's nobody around to fix it, I can't help but wonder if it would be all that difficult to build an independent micro-repair-bot that would piggy-back on the rover. (Think R2-D2 from Star Wars, or DRD's from Farscape, but smaller.) Then if something should fail on the rover, the ground controllers would have a means for getting a detailed report on the status of the robot. It could do some basic maintenance (like clearing dust off of the solar arrays, or removing a rock jammed in the wheels), or possibly more sophisticated (like replacing or bypassing a failed electronic component).

When we get to the point when the robots that we send out into the cosmos are adaptable, reconfigurable, and repairable without requiring human presence, then we may begin to see some interesting possibilities for what can be accomplished by robotic explorers. Until then, they will continue to be simple extensions of our own senses, mere tools with which we manipulate the universe.

Robotic Astronomy

I knew it probably wouldn't take very long to find people writing about robots and robotics being used in space exploration. Take for example this recent article over at Universe Today. The first half of the article discusses the history of robotics, both in early sci-fi literature and more recently in everyday usage in industry and the home. The article ends with a description of the emergence of the robotic observatory. These observatories are further enhancing the already impressive capability of amateur astronomers to make significant contributions to the field.

This type of technology will almost certainly be deployed when NASA returns to the moon. I wouldn't be surprised if one of the first things they do upon their return is to set up a robotic observatory. Even a relatively modest setup could potentially rival some of the capabilities of the Hubble space telescope. Being located in close proximity to the proposed lunar outpost, the observatory could be upgraded and repaired on a fairly frequent basis (assuming the continuing presence of astronauts at the outpost and frequent resupply transports). With proper planning of upgrades, the capabilities of a lunar observatory could eventually be expanded far beyond that of the Hubble.

In other news, Google is pitching in to help with the data management aspects of a new astronomy collaboration which intends to capture the night sky in motion. Last month Google also announced that it would be teaming up with NASA at Ames Research Lab to help them handle the vast amounts of data that have been pouring in from the agency's robotic probes for the last fifty years.

For astronomers, data glut has always seemed to be a problem. It seems like every new instrument or observatory that comes online is capable of generating many times the amount of data than its operators can reasonably process. For a good example of how this data glut is benefiting one particular astronomer, take a look at this article by Phil Plait of Bad Astronomy regarding the Hubble parallel program. The good news is that much of this information is quickly released to the public. The bad news is that the information is not always easily accessible. Hopefully, Google will be able to help in that respect.

And finally (for this post anyway), Bruce Irving over at Music of the Spheres posts a brief observation about the proliferation of robotics in the home.

A new year, a new focus.

Well, it happened. I have pretty much let this blog atrophy into irrelevance. (Not that it was ever relevant to anyone other than myself.) The thing is, I find myself at a decided disadvantage. There are so many excellent spaceflight related blogs out there, and they all seem to be run by much more qualified individuals than myself and who apparently have much more free time to blog than I do. These individuals do such an excellent job covering the latest "new space" news and speculating on possible future spaceflight architectures that I find I have very little additional insights to offer to the discussion.

I've also been thinking alot about what I'm going to be doing next with my life. I'm nearing the completion of my dissertation research in Computational Engineering, and am beginning to look forward to doing something useful in the area of spaceflight research and development. Since I started this degree program, so much has happened in the area of spaceflight and so many opportunities have opened up, that I can't wait to get out there and start contributing.

Of course, my personal goal all along has been to one day become an astronaut. However, I find that the particular set of research skills I have been developing over the past several years (developing computational simulation technology in support of NASA engineers designing and building the next generation of rocket engines) may not be directly applicable to the duties of an astronaut. At best, I am on track to become a rocket scientist, or propulsion engineer for NASA or any of the emerging companies focused on space launch and transport. In the near term, advanced propulsion technologies are fascinating to me and I would love to have the opportunity to work directly on the development of new rocket engines. However, in the longer term, I am concerned that this particular career path may not put me in demand when in comes to being selected for astronaut duty.

In light of all of this introspection, I've been reviewing my interests, talents, and experience to date, and I think I've found a field of expertise that may be much more relevant to astronauts in the very near future. The way I see it, when people finally start going into space to get some real work done, there will most likely be a great need for robotic assistants to accomplish many difficult and dangerous tasks. An astronaut trained to operate, repair, and modify these robotic helpers would be invaluable. I've always had an interest in robotics and a talent with computers and programming. I also have some limited experience designing and building a very primitive robot for my Masters thesis project (an automated data acquisition apparatus in which a PC ran the experiment, collected the data, and presented the results to the user).

So, with the new year upon us, I have decided to begin to look into the current state of the art, and near future possibilities, of robotics, with particular emphasis on space exploration applications. I will attempt to document my research on this blog. I do not yet know if there are others out there already blogging this particular angle on space exploration, but I hope I will be able to compile and distill some useful information that may be of interest to others.

Ad Astra, Per Aspera