Red Planet Bound

Robots Are No Substitute For Human Space Exploration

By Evan Plant-Weir

Image by author using Licensed Elements (original image of rover mast head by NASA)

Space exploration is not just about gathering data.

By and large, the last few hundred days on Earth are not going to be remembered fondly. Few will recall the COVID-19 years with a sense of happy nostalgia. Ultimately, however, this time won’t be entirely defined by the beating we took at the hands of a pandemic. Despite the many tragedies and challenges therein, we still managed to pull off some pretty remarkable things.

Somewhere high on that list is the recent trifecta success in the robotic exploration of Mars.

In February, spacecraft from three nations reached Mars in close succession. Since then, these missions have collectively knocked it out of the park with a series of impressive firsts.

NASA – now a seasoned veteran of robotic Mars exploration – amazed us with the first controlled flight and audio recording on another planet. As if that’s not enough, their Perseverance rover converted Martian atmosphere into oxygen for the first time (an important prerequisite for Mars settlement).

With Al-Amal, the UAE became the first Arab nation to establish a scientific presence at Mars, achieving that milestone on their opening attempt.

The arrival of Tianwen-1 marks China’s inaugural visit to the red planet, and the only time that a nation has deployed an orbiter, lander and rover during their first successful mission to Mars.

We’re getting good at this.

In fact, we’re getting so good at sending robot explorers to the red planet that you may begin to wonder… why would we ever bother sending humans? Why trouble with the expense and risk of transporting squishy hominids when we can just send metal and silicone instead?

It is difficult to overstate the scientific and societal importance of robotic space exploration. Each of these orbiters, landers and rovers have value in and of themselves, but they are nowhere near the culmination of our potential.

These robotic forerunners are laying the groundwork for their human successors, whose capacity for science and exploration is not only vastly broader, but substantively deeper.

The human body is a far superior mechanical system for generalized planetary exploration. Our brains, too, are uniquely suited for the investigation of Mars because of one vital capacity that no rover can carry, and no communications satellite can transmit: direct conscious experience.

Well in Hand

Credit: NASA (Source)

When I first had the pleasure of listening to NASA’s Perseverance rover driving across the Martian surface, I was astounded, and just a little amused by the juxtaposition in that soundscape. The haunting beauty of those first sounds recorded on another planet was punctuated by an almost cartoon-like humor.

This feat of engineering, built and operated by some of the brightest minds on Earth sounded as if it were squeaking and bumping along like an antique tricycle.

Of course, these noises don’t do justice to the rover’s exceptional sturdiness. This is just the sound of metal wheels in contact with rock and sand, recorded by a microphone that wasn’t meant for surface operations.

Perseverance does, however, share one characteristic with a rickety vintage tricycle: it is very, very slow.

The average human walking speed is around 1.3 m/s. When crawling, most of us move at about 0.5 m/s. At full throttle, Perseverance rolls along at 0.04 m/s. A human being – shuffling on hands and feet – moves more than twelve times faster than the most sophisticated rover yet deployed on Mars.

Of course, speed isn’t all that matters, but the differences in functional mobility don’t stop there.

Relative to a human explorer, rovers are highly restricted in their freedom of movement across terrain. An astronaut can navigate through a cluster of rocks that would be impassable for Perseverance, walk freely over a patch of sand that might hobble a rover, or scale a slope that would flip their mechanical counterparts upside down.

But what of the newly christened quadcopter? Surely, future iterations of flying Mars drones will possess mobility that surpasses us bipedal mammals.

Even then, the flexibility of an astronaut would far outstrip that of remote systems.

Robot hardware is super-human in some precisely defined tasks. For instance, a human hand could never hope to achieve the steadiness and accuracy of the Perseverance Supercam. Whether they roll or fly, however, these machines have hard limitations on the breadth of their abilities once they arrive at a location of interest. With little exception, they can only do what they were specifically designed for.

Humans, on the other hand, are proficient generalists. Our bodies are considerably more multipurpose and dynamic than even the most impressive near-term robotic systems. Machines are still a long way from matching our overall dexterity and flexibility.

Similarly, the software running these robots is super-human within highly specific boundaries, but no match for the versatility and adaptiveness of our brains.

Compared to robot explorers, astronauts can move faster across more variable terrain, and they can repurpose their bodies on the fly to accommodate an incomparably large set of tools and tasks. They can make creative, novel and autonomous decisions in real time, where a rover would require meticulously planned instructions transmitted with a communications delay.

Consider the industrial and manufacturing sector here on Earth. Unskilled human labour continues to be used in factories and warehouses, despite the enormous financial incentive for corporations to do otherwise. Even in a low-complexity work environment, and even when motivated by the almighty dollar, you just can’t beat the near-infinite task flexibility of a human.

At this point, detractors of crewed Mars exploration will reliably vibrate with the neurotic energy that compels them to point out, ad nauseam, that space is dangerous for people. Yes, the hazards of interplanetary travel present a barrier to entry for human explorers. There is an up-front cost in learning to keep astronauts safe and healthy in deep space. Nothing about that challenge is insurmountable, we’re very good at solving problems like this, and the short-term investment in figuring that out will pay off considerably down the road.

We’ve got work to do, but – in the long run – human explorers are the practical choice.

A human geologist can do in a week what the Mars rovers can do in a year.”
– Frances Westall, Astrobiologist at the CNRS (source)

It’s no wonder then, that part of the overt mission objective for these robotic missions is to “pave the way for future human exploration of Mars”. The most salient difference between a robot and an astronaut, however, has nothing to do with practical considerations. A rover could never take the place of an astronaut, because of something a little less tangible and a lot more consequential.

Putting Our Minds to It

Image by author with licensed elements

Why are the Apollo missions so frequently regarded as the current peak of space exploration? Is it because we gathered additional data on the nature and composition of the moon? Is it because we shipped an assemblage of titanium and aluminum to another world?


Six hundred and fifty million people tuned in to see the lunar landing, not simply because it was an achievement in science and engineering, but also because it was an opportunity to witness the broadening of human experience.

Those astronauts encountered a range of sensation and awareness that is qualitatively different than anything available here on Earth.

It felt a particular way to stare out across that alien, monochrome landscape, and there was a certain comprehension found in observing Earth as a distant object. The resulting constellation of thought and emotion was so novel that it was given a name.

This psychological phenomenon, the overview effect, has such a strong impact on astronauts that it drives them to engage in humanitarian efforts, create art and even form non-profits aimed at simulating and sharing that experience.

We’ve barely dipped our toes into the immensity of outer space, and yet we have already encountered the intangible experience and profound inspiration available by traveling beyond our atmosphere.

Robots do not experience the overview effect. Their data streams can reveal a great deal about the appearance, nature and composition of Mars, but they tell us very little about what it is actually like to be there.

Credit: Artists Ren Wicks (source)

How would it feel to gaze down into Valles Marineris, a canyon system so deep that you could hide most of the Rocky Mountains inside of it? What novel blend of thought and emotion will the expansive landscapes of Mars stir in the minds of explorers and settlers?

What is it like to dance in partial gravity, or to sing in a pressurized lava tube? Which looks better under the Martian sky, watercolor or acrylic? What’s the best way to dust regolith off a solar panel when you forget your brush inside the habitat? How does it feel to be a human on a new planet, engaged in the single greatest adventure in history?

There is a deep well of insight available in the resolution of these questions, and no robot can answer them for us.

The longer we stay on Mars, the deeper and fuller this well becomes. Eventually, these unique frames of mind will make the pillars of new culture and tradition. The foods that taste best from vegetables grown in reclaimed regolith will shape Martian cuisine. New forms of art and literature will take root, with a style reflective of interplanetary life. Technical and scientific quandaries specific to living on Mars will spur unexpected means of innovation and discovery. The red planet will be home to future Leonardo Da Vincis, Marie Curies and Louis Armstrongs, who’s inspiration will derive from the myriad nuances unique to Martian life.

All of this potential will be lost if we choose not to go ourselves.

I would be remiss if I did not point out that robots will still be necessary in any case. Like so many misunderstandings regarding space exploration, this is not a mutually exclusive proposition. In fact, the number of robotic systems on Mars will no doubt climb drastically with the arrival of their human counterparts and the resulting flurry of activity. As is the case on Earth, there will always be situations for which robots are best suited.

So, why not leave Mars to the robots? Because you can’t build human adaptivity into a machine, and space exploration isn’t just about gathering data. It’s about expanding the bounds of human experience into new and challenging corners of reality, and – as a pandemic’s worth of virtual gatherings and shutdowns have reminded us – there is just no substitute for doing it in person.