by Richard Obousy
After a stint as project leader for the Project Icarus starship design study, Richard Obousy now serves as Module Lead Primary Propulsion for the effort. Dr. Obousy’s doctoral work at Baylor University focused on the possibility that dark energy could be an artifact of Casimir energy in extra dimensions. For Icarus, he has pivoted to the study of fusion propulsion systems for this ongoing reworking of the original Project Daedalus concept. He’s also fascinated with the possibilities of getting off our planet more easily and establishing a human presence on Mars, all ideas he was able to explore at the Mars Society’s latest meeting, from which this report.
As a native of Texas, living only a couple of hours drive from Dallas, I was thrilled to discover that that was where the Mars Society planned to hold its 14th International Mars Society Convention. This was a perfect opportunity for me to meet space enthusiasts, to present to this community some of the ideas coming out of Project Icarus, and to learn from a successful non-profit foundation how to engage with its members, while delivering something valuable to the field of Mars research.
For those not familiar with the Mars Society, it is a non-profit charity founded in 1998 by Mars exploration luminary Bob Zubrin. The society is devoted to the cause of exploring and, ultimately settling, the red planet. The society has over 4,000 members and is active in over 50 countries worldwide. A large number of volunteers engage in public outreach programs in an effort to foster support for Mars research and exploration, and a notable feature of the society is its commitment to ongoing technical projects – the most exciting of which are arguably the research stations that the society has set up in hostile environments. The purpose of these research stations is to simulate the conditions and environment that early Mars explorers might face. Currently there are research stations in both an arctic environment and a desert environment, representing evidence for what can be accomplished by a devoted collection of volunteers.
The conference itself spanned four days, as numerous presentations relating to Mars exploration were delivered by a selection of scientists, engineers, and private hobbyists. An entire afternoon session was devoted to the topic of nuclear rockets and several of the original engineers involved in the NERVA (Nuclear Engine for Rocket Vehicle Exploration) program presented. NERVA was a fascinating facet of the US space research program, leading to nuclear rocket engines actually being certified as flight worthy in the late 60s, after extensive testing. The untimely cancellation of NERVA was largely a result of the Nixon administration’s lack of interest in the manned exploration of Mars, which it saw as both costly and strategically irrelevant, with the space race already ‘won’ after the successful Apollo moon landings.
One talk that still resonates with me was given by Dr. John Hunter, an ex-theoretical physicist turned space engineer. Hunter is the director of Quicklaunch, a company planning to use a light gas gun to launch payloads into space. The basic idea behind the gas gun is to use a large piston which imparts force to a gaseous working fluid through a smaller diameter barrel which contains the projectile to be accelerated. The gun that Hunter is working on gives the projectile, a single stage rocket engine plus payload, an initial speed of 6 km/s which launches it to approximately 100 km altitude.
Image: Quicklaunch’s larger QL-1000 systems will be built after the smaller QL-100 versions have proven high reliability. Each QL-1000 is a $500M system delivering up to 5 launches/day. After servicing one customer they can switch azimuth and launch angle to accommodate a different customer. At T=0 the vehicle leaves the muzzle and the four sabot petals are stripped away. Meanwhile the muffler closes behind the vehicle, capturing 99% of the hydrogen to be recycled. Credit: Quicklaunch.
At this point, the rocket engine fires and gives the projectile the final kick it needs to circularize its orbit. Using this technique, Hunter believes that he will be able to attain launch costs of $500/lb. Contrast this with the Space Shuttle costs of around $10,000/lb and the economics quickly makes sense. Even Elon Musk’s heavy Falcon launcher will be around the $1000/lb mark, so Hunter’s gas gun looks like an attractive option! One obvious limitation is that the high gee forces (~100 g’s) experienced during the initial launch exclude the possibility of human passengers, and so the gas gun will likely focus on launching propellant payloads. The resulting fuel ‘depots’ could enable future manned lunar and Mars exploration, if Quicklaunch were used in tandem with traditional launch systems. I encourage anyone interested in this fascinating technology to take a look at the Quicklaunch website which contains more details on their plans and accomplishments to date.
Image: Quicklaunch in Earth orbit. At T=9 minutes final maneuvering is performed until the vehicle docks with the depot. At that point a line is opened allowing the propellant to communicate with the rest of the depot. Propellant types will include both storable and cryogenics. Standard propellants are RP-1, LH2 and LOX. In addition xenon, argon and water can be delivered. Credit: Quicklaunch.
Zubrin himself gave a fascinating talk titled “VASIMR: Hoax or Silver Bullet,” arguing hotly that Chang-Diaz’s VASIMR is unlikely to produce any better efficiency than current ion engines, and that the promises being made regarding the utility of the engine are exaggerated. Zubrin believes that research into VASIMR is nothing more than a distraction, since NASA is adopting the mindset that the VASIMR is a necessary technological precursor for a manned mission to Mars. Zubrin argues that a manned Mars landing can be accomplished using off-the-shelf technology available today, for a small fraction of the $450 billion price tag that NASA initially suggested in the “90-day Study” in 1989.
Another of Zubrin’s talks, titled the “Transorbital Railroad,” urges NASA to devote a budget of $1.2 billion per year to pay for launches, possibly using SpaceX technology, to deliver payloads into orbit. The payload mass would be sold to paying customers at $50/kg, and if there were unused payload space, this could be filled with tanks containing water, kerosene and liquid oxygen. These tanks would then be left in orbit and made available to anyone who could reach them. Using the Falcon Heavy launch vehicle, Zubrin estimates that 765 metric tonnes could be launched annually. The main thrust behind this heavily government subsidized plan would be to create a space-based economic sector welcoming to entrepreneurs. His belief is that the tax revenues that would be generated from this endeavor would pay for the Transorbital Railroad many times over. The name Transorbital Railroad is adopted from the history of the settlement of the American West, where the building of the Transcontinental Railroad opened up a plethora of economic opportunities for Americans of the era.
Image: Mars Society founder Robert Zubrin. Credit: The Mars Society.
There were many more talks at the conference, equally worthy of discussion, but the ones reviewed here probably had the biggest impact on me for one reason or another. I was happy to meet with Bob Zubrin at the speakers party one night, and share with him some of the exciting work being conducted by Project Icarus, which was met with enthusiasm by Bob – a former nuclear engineer. Being involved in the area of interstellar research, I was reaching, somewhat, into a community whose goals vary from my own field. However, I felt that there was a common theme and a collective unity that binds the Mars Society with those of non-profits like the Tau Zero Foundation and Icarus Interstellar – namely a core of dedicated volunteers pushing a vision forward, while being supported by a network of collaborators spread across the globe. The success of the Mars Society is a testament to what can be accomplished by such volunteers and I was genuinely happy to be a part of that last weekend.