The Unknown Unknowns of Mars
A small contribution to a big discussion adding some signal to the noise
There are things we know well enough for practical purposes. These are knowns.
Then there are things we know about, but don't know the details. If we're venturing up a mountain range that we've never hiked or researched, we don't know what specific problems we'll have, but we know that there'll be some combination of terrain, weather, wildlife, climbing, dead ends, etc. These are known unknowns: we know of the existence of some dimensions of the problem for which we don't know the specific values in this instance.
Then there are problems that we can't foresee before we're into the process and there's been some adaptation or settling in. Corrosion from saltwater and fatigue from thermal cycling only became known problems in shipping once metal ships were common. Before that, people making [wooden] ships didn’t think about them: they were unknown unknowns. Taking science and creating engineering is a common source of unknown unknowns.1
Space: the final frontier...
In disruptive innovations or frontier-expanding endeavors, like space exploration, there are many known unknowns, for which there's ongoing measurement and design and use of lab rigs (including lab rigs in space): for example, we’re testing ways to grow food in space, we have roaming laboratories on Mars (rovers) taking soil samples, and we’re in the early phases of a mission to return those samples to Earth for further study.
There are also other things that we only discover as we go further and farther into space, unknown unknowns: until we had people living in free-fall for significant periods, bone density loss from lack of gravity was an unknown unknown.
The progress of unknown unknowns to known unknowns to knowns is why early space exploration had many intermediate steps: get to space; do an orbit; do an EVA; maneuver and mate two ships in space; go around the Moon; land. At each step unknown unknowns were discovered, characterized, measured, understood, and solved or otherwise addressed.
Many of the unknown unknowns must be experienced in process (like the thermal cycling fatigue of metal in ships), and some of them are emergent properties of the interaction of the environment with the new innovations (like cyberbullying). Figuring them out takes time, which is why complex endeavors tend to follow phase-gate project structures: “get this phase working and well-understood before you can move on to the next (i.e. open the gate).”
On a sad — shameful really — side note: the time passed since a human last stepped on the Moon is now almost 3/4 of the time between the first powered flight and the first human step on the Moon:
For shame!
We seem to be taking the first tentative steps to get back to the Moon. At least there’s that! What about Mars?
Mars: an optimistic position moderated by some realism about dealing with unknown unknowns
Some of us who like space exploration get occasionally distressed by fellow space enthusiasts who believe that the steps involved in conquering Mars can be skipped: that we can have a civilization on Mars without first having a manned mission, a research base, a permanent presence, and long-term residents, each for some time before progressing to the next step; that these steps aren’t necessary to find and solve the unknown unknowns of Mars.
This optimism has some positive effects, because it counters the relentless naysaying of those opposed to space exploration tout court, but naïve optimism can interfere with the hard realities and the serious work that must be done before we can have a family vacation in the Four Seasons at the base of Mons Olympus.2
Then there's the much larger group of people who seem to be against space exploration for… reasons, and now that [admittedly a controversial figure] Elon Musk has reiterated his desire to have a city on Mars by 2050, they seem to have gone all-in against Mars colonization again.
In response there are plenty of people making the pro-space exploration argument and specifically the case for Mars. Peter Hague wrote a post discussing some of the objections to Mars colonization, useful for reference.3
Here we'll just note that there's an asymmetry in the arguments regarding the unknown unknowns of space exploration.
Benefiting from unknown unknowns
Opponents of space exploration who bring up dangers from unknown unknowns (common ones: radiation exposure during transit and psychological issues from isolation) tend to ignore or dismiss the potential gains from space exploration that cannot be predicted (the positive variant of unknown unknowns). These, historically, have been more important, and the solutions to the dangerous unknown unknowns themselves tend to become sources of positive spillovers.
Consider an unknown unknown obstacle that becomes a known obstacle in one of those intermediate steps towards colonization. That’s an obstacle for which, if history is our guide, and absent violations of the laws of Physics, human creativity finds a solution, a work-around, or a coping mechanism:
Solution (solve the problem): inept car drivers brake too hard on slippery surfaces, making the wheels lock and losing control,4 so motion sensors combined with adaptive control algorithms were used to develop anti-lock braking systems (ABS) that modulate the braking action of the driver and keep the wheels from locking and the driver from losing control.
Work-around (make the problem irrelevant): it was hard to keep pendulum clocks stable in sailing ships in the open ocean (knowing the time at a reference location, say London, is important to determine longitude when you don’t have electronics), so instead of trying ever more complex stabilization mechanisms to keep the pendulum enclosure vertical, the solution was to use a balance wheel clock mechanism, which is independent of gravity.
Coping mechanism (accept the problem and find a way to deal with its consequences): to limit the bone loss from being in free fall, astronauts on the ISS have to do several sessions of resistance training and cardio per week.5
The solution to an unknown unknown problem or the unknown unknown benefit of something developed for space, usually called a technology spillover, sometimes leading to a spin-off company from the technology developer, are sources of hitherto undiscovered value.
Asserting that there’s no possible value that’s worth the cost and risk of space exploration is not just a failure of imagination, it’s a denial of the history of technology and innovation. It’s particularly strange to see it now, when in the last 15 years our lives have been changed in innumerable ways by the smartphone — a technology that 25 years ago would have been forecasted as incremental, had it been posited (then, most people used cell phones as, well, phones, i.e. real-time voice communication devices; youngsters texted some).
Confidently forecasting how people will use a new technology is a great way to entertain people a decade or two later. Unwittingly, that is.
As for those solutions, work-arounds, and coping mechanisms for unknown unknowns —even some that might seem highly specialized prior to their deployment (like all three examples above) — many end up being widely used, not necessarily for the application or market that led to their development.
Modern anti-lock brakes were developed for airliners and trains, now they’re basic safety devices in cars and motorcycles.6 Pendulum-free clock mechanisms were solutions to the problem of determining longitude on sailing ships, but they became pocket watches and eventually wristwatches; and the use of resistance training for astronauts dealing with bone density loss contributed to research on the topic of people suffering from bone density loss on Earth (e.g. osteoporosis).
For more space-related examples, Nasa keeps a page of technological spillovers of the US space program used by outside companies (spinoffs) at http://spinoff.nasa.gov/ and Wikipedia has a friendlier (though not as thorough) version at https://en.wikipedia.org/wiki/NASA_spinoff_technologies.
The relentless focus on the negatives, the fear-mongering based on unknown unknowns, and the dismissal of potential, hitherto unseen, benefits are not a sign of thoughtful or honest consideration of spacefaring.
Quite the opposite, in fact.
To end on a happy note, the Mars Ingenuity helicopter, an example of bleeding-edge engineering from the materials to the solar panels to the airfoils to the control systems, all adding contributions to our shared technological basis on Earth, survived a long Mars Winter shutdown and is now flying again.
We made a robot that’s flying on another planet. One day we will fly there too.
One way to tell engineers from the foundational scientists of their fields is how much the knowns of engineering are unknown unknowns of the basic science. Engineering is based on science, but the core science of any engineering project is taken as granted by the engineers, all the engineering problems come from executing the science in the field:
From the viewpoint of a chemist trying to figure out the production of poly-[ethylene terephthalate], all the actual engineering issues are unknown unknowns; the chemist focuses on the chemistry as it happens in a lab, while all the problems the engineers have to solve take that chemistry as given and solve the real-world problems of making PET plastic. (The differences starts with chemists ordering reagents in grams with part per million or billion impurities and trusting that’s what they get and chemical engineers ordering them by the rail tank car with percent impurities and having to test them on arrival to be sure of what they’re feeding into the reaction vessels.)
Some of the optimism of the more technically proficient among the optimists comes from the disconnect between understanding the core science and understanding the engineering realities of making that core science work productively and economically at scale outside of a laboratory environment, just like in the footnote above (which is why it was there, totally not just to make fun of scientists trying to do engineering).
We’ll add here to the “we haven’t colonized Antartica” nonsensical argument the counter that, on top of the points Peter Hague’s post makes, there’s no practical application (other than science and selfies with penguins) that can be done in Antartica that can’t be done in Northern Canada or Norway, and those two countries have better infrastructure and access.
But Mars is different from any place on Earth, and it’s conceivable that its lower gravity (and therefore easier to leave gravity well) can be an asset: for example, combined with its availability of raw materials to build a waypoint for exploration of the outer Solar System. Oyé, Beltalowda!
Because the wheel/ground friction regime goes from static friction when the wheel is rolling and staying in contact with the road, to dynamic friction (much lower) when the wheel is locked and moving relative to the road; this lowers the ability of the wheel to transfer braking or turning force from the car to the ground.
A proposed solution that removes the need for this coping mechanism is using rotating space stations and ships, which simulate gravity via centripetal force.
Brake modulation systems existed prior to the motion-sensor plus adaptive control system that characterizes ABS; the difference is that those systems reacted only to the locking of the wheel (or sometimes only to the vehicle speed and pedal pressure, being completely open-loop mediator systems), not to the movement of the car with respect to the road.
The key difference is that modern ABS, using motion sensors, operates in closed loop with the movement of the vehicle relative to the ground, while early systems didn’t get feedback from the movement relative to the ground, only the wheels, if that. For obvious reasons these early open-loop systems were inadequate for high-momentum vehicles like trains and airliners braking in slippery conditions.