Robotic Space Probes — Penny Wise, Pound Foolish
Sometimes the most educated thoughts on a subject are dead wrong.
This post is the expanded form of a reply comment I left on a youtube video from the Vintage Space channel.
Firstly, I need to duly summarize the points the video made, putting as little of my own editorial spin as I can manage.
- Focus on Mars is misguided. One reason is that boots on the ground won’t increase our knowledge about the planet much.
- Many other destinations are more interesting than Mars. Reasons why are various, but some Jovian and Saturn moons have more lifelike conditions than Mars. Venus has the possibility of airships with breathable gas.
- More smaller missions to the outer solar-system moons would be better. Later it is elaborated that more diversity in missions would be better, and that it would be a shame for us to dedicate all/most resources to one big Mars program.
- A holding pattern with Mars would be good until we have a better idea of what’s needed to support human presence.
- The motivations for Mars is “for the sake of humans on Mars” while we have the right reasons for exploring other planets and other moons.
- As a concession, the vlogger “could get behind” a manned mission to orbit Mars while controlling things on the surface.
The final point, #6 is ripped almost directly from the Aldrin vision of Mars. More details of his idea are in the book:
Mission to Mars: My Vision for Space Exploration
"Any time an Apollo-era astronaut steps forward with ideas for our future in space, it's time to stop what whatever we…
These Opinions are Very Common
Actually, the above philosophy has basically been the de-facto guiding principles of NASA investment for decades now. This is almost universally the expert opinion (I’m using “expert” a pejorative here, in the spirit of the Black Swan book). There is a precautionary principle at work, where taking big gambles could result in dead bodies in space, breaking that taboo and softening public support. There is also a budgetary standoff, where Congress almost certainly wouldn’t fund a large project to the levels needed to make it work. There’s the hazard of purpose-built infrastructure going away in a whiff of smoke after the object has been accomplished, like with Apollo. Plus, there’s the apparent success of robotic missions to contend with. These have built up a very high success rates and offered the public many tangible wins.
Rhetorically, this is a strawman argument. It takes a modern educated position and compares it to an antiquated, largely debunked, position. The proper comparison is between another educated and modern position.
This status-quo position is that of a focus on science. I contend that we have a rapidly emerging intellectual camp of people who argue that we should have a focus on infrastructure. It’s the focus on science that has led to the domination of space probes as the primary (and almost exclusive) means of conducting exploration.
Here is a link to the actual comment I left, which you could read for a more abbreviated version of the arguments I’ll go through here.
This is not Moon-First, Mars-First
There is somewhat of a long-running divide among space advocates about whether we should go to Mars or the Moon first, and this is not that discussion. The title of the video I’m responding to certainly seems anti-Mars, but this is only because Mars is the current center-of-attention. The video is not in favor of the Moon, it’s not expressing favor for either. The focus on the video is a grand diversity of exploration targets throughout the entire solar system. Per the arguments laid out, achievement of these goals within a resource-constrained environment would mean cuts to a manned spaceflight program.
These arguments hold up as long as your perspective is science-focused. The problem we encounter is that a purely science goal is self-defeating.
Why Mars is a Worthy Goal
If we’re going to keep our heads in reality, then we have 4 places that are worth a darn — The Moon, Near Earth Asteroids, Phobos, and Mars. Sending man-rated Zeppelin-style airship on Venus would be outrageously expensive and would ONLY ever be useful for unsustainable trips to Venus. This exact point was made earlier in the video that multi-destination vehicles are vastly better in terms of resource prioritization. Unfortunately, you just can’t explore Venus without doing destination-specific engineering and design.
Mars is, by far, the best option to create a self-sustaining base. Mars could host a 200,000 person space city. You can’t say that about anything else without it being obviously orders-of-magnitude more expensive than the Mars option. If we ever built such a city (the Musk vision in a nutshell), its primary economic activity would be spaceflight. A sustainable inter-planetary presence would support exploration to all the places talked about in this video and much more. It’s not either or. It’s both or none.
Robotic Probes are One-Off Affairs
Robotic missions aren’t worthy of comparison to a Mars settlement objective because they are never ever sustainable in any sense of the word. Categorically, we send robots up for them to transmit back data (except for just a handful of sample return missions). Every robotic mission takes a vast amount of investment in novel robotics engineering, leading to an economic trap of launch costs spiraling out of control. Every dollar you spend on the payload is a dollar you don’t spend on the launch vehicles, because again, constrained resources.
Again with the disclaimers… this doesn’t mean that I don’t see any value in future Venus probes, and an atmospheric probe would be super interesting and develop a couple of important technologies. But this sort of thing should be achievable at comparatively low cost among a much larger budget.
Make Spaceflight Routine
Do you like the idea of reusable rockets? Then you’re backing the wrong horse with robotic missions. Focusing on science and robotics leads to fewer launches at higher cost. Only some form of manned flight will result a virtuous cycle of higher demand, innovation, and lower launch costs. This is what the COTS program tried, and hardly a decade later reusable boosters are already being flown. If you de-emphasize human flight, then you pull out the rug on the concept of regular supply flights and any impetus to improve launch economies.
Regular supply flights are absolutely vital if we are going to have any future in space at all. In terms of economics, this is one of the few things that will provide a steady demand for launch services, will consume launch services a large part of its budget, and can increase our capabilities while reducing costs.
One thing that we need to be doing more of is engineering missions that can be sent up in multiple pieces and constructed in orbit. This is a component of most Mars architectures, even when employing extreme heavy lift rockets. It makes you wonder, what would be so impossible about doing the same thing with slightly more launches with slightly smaller payloads? This is the path forward if we are to have a path forward at all.
It’s not About Manned Spaceflight, it’s About Infrastructure
Don’t get me wrong, it’s totally possible to do Mars the wrong way — like what we did with Apollo. But we need sustained space stations and surface stations in order to get human kind’s foot in the door of space. Those stations need to be hosting propellant depots and developing ISRU, or else our space program will be stuck in the 20th century forever. Those stations could be totally robotic, that would be fine with me, but that’s just not going to happen.
The only way forward is to advance our supply infrastructure in space. Then we get more payload for less. More moons explored, more science done. If we ignore this and focus only on the number of moons we can land robots on, then we will never advance. In that scenario our space program will stagnate and falter, and perhaps our species with it.
Bigger Budgetary Picture
This is the part where I go through the list of “I’m not saying this” to avoid the predictable responses.
Clearly we have made tremendous progress with space telescopes and robotic probes, and only a fool would suggest getting rid of these programs. But there is something very real and very clear that these do not do. They don’t change the overall ballgame of spaceflight, and they do this even less-so when they run over-budget.
In very basic and crude terms, we need to be spending some base-level amount of our space exploration budget on launching rockets, and the lower this number goes, the worse our prospects look for anything ever changing. We will be forever Earth-bound if the only thing we send are expensive robotic orbiters and landers.
I think the poster child of the evolution of recent decades is the use of nuclear power sources in robotic probes. Note that these do not tend to be used for manned missions, so take a minute to consider that. What is different about each? For one, the robotic missions tend to have lower power demands. For another, the robotic missions have a harder time dealing with the contingencies of problems with unfurling solar panels. Even though an EVA is costly and risky, it’s better than the complete loss of a mission. But the supplies of nuclear material are extremely limited and extremely expensive. This, like many other innovations, have further contributed to the death-spiral of more expensive launches, leading to more expensive payloads, leading to more expensive launches.
That’s why some fraction of the budget really needs to be dedicated to programs that have a certain cost and payoff profile. We need flagship programs that involve putting a lot of mass into orbit and beyond, involve developing technology that make future endeavors more viable, and involve somewhat reliable schedules repeating the same activities. For all its flaws, this demands manned spaceflight and programs like the ISS are keeping the glimmer of hope alive for the time being.