I think this benefit of unmanned over manned will increase as time goes on. An unmanned spacecraft can be small and low cost, in the future we may soon even have interplanetary Cubesats and be able to launch a mission as far as Jupiter for $5 million. They would communicate using lasers to Earth and get power from solar panels
Dandelion Mars Lander
Dandelander mission concept
Europa
Tiny Satellites Could Hitchhike To Europa With Bigger NASA Mission Concept
And many other proposals, see Planetary CubeSats Begin to Come of Age
Try fitting a human mission into a 10 cm cubed box :).
Short of some "Tardis technology" bigger on the inside, a human mission has a minimum size and weight.
It has to be
You can design them to go to places that humans can't go without greatly increased protection, or that are currently impossible for humans.
Such as close to the sun, or to the surface of Venus, or the high radiation levels of the Gallilean satellites of Jupiter. Or they can drill kilometers below the surface of a planet as in plans for moles to study subsurface of Mars.
They can be fired at a planet at kilometers per second and still survive (in case of ideas for "smart penetrators").
If you don't need your spacecraft or it has nothing to do, right now, for instance on a long interplanetary journey, you can just put it into a resting dormant state. You can never do that with humans.
On the surface of a planet, you can leave it observing something for months on end, or doing a long experiment, and it will never get bored or tired, or require resupply to stay alive. Just solar panels, or an RTG, is enough to keep it healthy indefinitely.
So far, we don't have any way to do that with humans. There are ideas for human hibernation which may come to fruition some day, but so far it is not practical to do this.
You can sterilize a robotic mission to whatever level you need. Humans have a hundred trillion microbes in ten thousand species that co-exist just on our bodies. There is no way you can sterilize a human occupied spacecraft and the inhabitants be still alive.
Robots can be sterilized to the requirements needed for planetary protection. There it is just a technological matter.
Humans could only explore a vulnerable location with spacesuits or similar that contain all microbes. We don't have the technology to do this in a spacesuit yet.
You could land humans on a vulnerable target, in principle, if you enclosed them in a totally impervious and immensely strong sphere and sterilized the outside. But what is the point? As they couldn't get out and just have to observe from inside? They might as well be in orbit and explore via telepresence.
Perhaps with future technology if our sphere can also be mobile and transparent, this could be a way for humans to explore vulnerable targets. Or even some very high tech flexible but totally unbreakable spacesuit. But we don't have that technology yet.
Anywhere in our solar system, once you get there, a robot can start roving over the surface or orbiting the target indefinitely. A human mission has to "dig in" and cover themselves with some meters of radiation shielding if they plan to be there any length of time.
The main advantage we have are that we can make quick accurate decisions to deal with unexpected situations. However, there is nothing usually that a robot on an interplanetary mission has to respond to instantly. Most robotic emergencies e.g. during landing on Mars happen too quickly for a human to respond anyway.
Given enough time, a robot on Mars or anywhere else in the solar system can handle just about anything, relying to a large extent on decisions made on Earth. But it is slower.
So it is mainly a speed advantage that humans have here. Since robotic missions are also lower cost, then especially as robotic capabilities increase, and costs go down further, you can compensate for this by better autonomy, and just sending more missions.
We can't yet build a robot that is as capable as the human hand. But are getting close. Maybe in future robots on Mars will have hands that they can use to repair themselves like a human mission?
Also this advantage is somewhat offset by the need to use spacesuits. The astronauts on the Moon had a lot of difficulty doing even simple tasks like drilling a short way into the surface. Your hands are stiff and clumsy, again due to the high pressure, needed to protect your hands from the vacuum of space. It's like trying to use your hands with your fingers each enclosed inside a garden hose.
A robot designed to drill, for instance, would probably do a far better job of it than a human. And humans may well find that many tasks are done more easily by telerobotics especially with improved technology, in the near future.
They may repair the ISS for instance, in the future, from inside, using telerobotics. More dextrous, and no danger of e.g. drowning in your spacesuit or being hit by micrometeorite during a spacewalk.
We like to see other humans doing daring missions. More interested in humans going to the summit of Everest than a robot.
Humans exploring the solar system can describe their experience, write poems, do paintings and so on.
However, as we get improved communications, then we can explore the solar system virtually.
Our rovers have a strong emotional appeal also. Experimenters on these missions like Curiosity, New Horizons, Rosetta and the Philae lander, and Dawn to Ceres - often feel as if in some sense they are there themselves. These robots are like extensions of ourselves, like mobile eyes and hands that we can send througout the solar system.
And if we use robots, then everything that comes back can be experienced by everyone, not just the astronaut explorers themselves.
And our senses are adapted to the Earth. We can experience blue skies, and the sea, and winds, and trees directly. We can sense via sight, vision, sound, smell.
Nobody will ever experience the Mars surface in this way, not present day Mars with its near vacuum conditions. Or Europa or Venus or even the Moon. Always you have a barrier of technology, your spacesuit, you look at it through a visor. And your eyes are not adapted to those conditions. Too much contrast in case of the Moon. In case of Mars, everything a dull grayish reddish brown (the images we see are hugely digitally enhanced to resemble a landscape illuminated by sunlight so that human eyes can interpret them).
So given that our senses are not adapted to these places, we may get our best and most direct experience of them through telerobotic explorers and our unmanned spacecraft.
The appeal of sending humans to space gets less as it becomes more routine.
The first mission of humans to the Moon was of great interest, fifth and final mission to the surface, though it was the most interesting of all for scientists, was something of a yawn event for most of the general public.
While robots continue to have an appeal. Because they are there for the science and exploration, the focus is always on what they can discover. And that gets the public engaged in the discoveries - probably more so than for a human mission where the human interest angle is the main thing that will get publicity. And science and exploration and discovery is something that continues almost indefinitely.
So, I'm sure humans have a role to play. We have advantages that make it worth while having humans "on the spot". Many of those at present for special situations where humans are needed. And also as explorers and adventurers, the human element of humans out there exploring the solar system has an obvious appeal.
These advantages may become less as our robots get more capable.
But at the same time we may have improvements in life support, be able to send larger masses into orbits, and find ways to support humans in environments where at present it is impossible because of the hazards or for planetary protection reasons.
So, I'm not saying that we should explore the solar system purely robotically.
But we can do a huge amount with robots, as our partners in this exploration of the solar system, and as extensions of ourselves as our eyes and hands and senses on remote moons and planets.
Dandelion Mars Lander
Dandelander mission concept
Europa
Tiny Satellites Could Hitchhike To Europa With Bigger NASA Mission Concept
And many other proposals, see Planetary CubeSats Begin to Come of Age
Try fitting a human mission into a 10 cm cubed box :).
MINIMUM SIZE AND WEIGHT FOR A HUMAN OCCUPIED SPACESHIP, NO FIXED MINIMUM FOR ROBOTS
Short of some "Tardis technology" bigger on the inside, a human mission has a minimum size and weight.
It has to be
- Physically large enough to contain humans, which can be dwarfs and double amputees, but still, it has to be physically quite large just to fit the human in
- Space for exercise.
- Launch weight at minimum the mass of the astronauts. But realistically, for a long duration flight, many tons of supplies as well for each astronaut
- Life support system to sustain the humans, and to remove build up of toxins that can harm us
- Spacecraft has to be built to hold in ten tons per square meter of atmospheric pressure, leading to bulky designs usually based around cylinders or spheres, like the ISS.
Robotic spacecraft can be any shape, and unpack to flimsy structures, even can be too light weight in construction to hold together on the Earth surface. - Humans need protection from cosmic radiation.
- It may need to spin for artificial gravity at any rate something needs to be done to deal with issues of zero g. Robots are absolutely fine in zero g.
- Risk tolerance is far higher. We could launch cubesats even with a failure rate of 50% or higher, even 90% and only 1 in 10 get there.
CAN GO ALMOST ANYWHERE
You can design them to go to places that humans can't go without greatly increased protection, or that are currently impossible for humans.
Such as close to the sun, or to the surface of Venus, or the high radiation levels of the Gallilean satellites of Jupiter. Or they can drill kilometers below the surface of a planet as in plans for moles to study subsurface of Mars.
They can be fired at a planet at kilometers per second and still survive (in case of ideas for "smart penetrators").
CAN GO INTO DORMANCY OR LOW ENERGY OBSERVATION STATES
If you don't need your spacecraft or it has nothing to do, right now, for instance on a long interplanetary journey, you can just put it into a resting dormant state. You can never do that with humans.
On the surface of a planet, you can leave it observing something for months on end, or doing a long experiment, and it will never get bored or tired, or require resupply to stay alive. Just solar panels, or an RTG, is enough to keep it healthy indefinitely.
So far, we don't have any way to do that with humans. There are ideas for human hibernation which may come to fruition some day, but so far it is not practical to do this.
CAN BE STERILIZED FOR PLANETARY PROTECTION
You can sterilize a robotic mission to whatever level you need. Humans have a hundred trillion microbes in ten thousand species that co-exist just on our bodies. There is no way you can sterilize a human occupied spacecraft and the inhabitants be still alive.
Robots can be sterilized to the requirements needed for planetary protection. There it is just a technological matter.
Humans could only explore a vulnerable location with spacesuits or similar that contain all microbes. We don't have the technology to do this in a spacesuit yet.
You could land humans on a vulnerable target, in principle, if you enclosed them in a totally impervious and immensely strong sphere and sterilized the outside. But what is the point? As they couldn't get out and just have to observe from inside? They might as well be in orbit and explore via telepresence.
Perhaps with future technology if our sphere can also be mobile and transparent, this could be a way for humans to explore vulnerable targets. Or even some very high tech flexible but totally unbreakable spacesuit. But we don't have that technology yet.
RELATIVELY UNAFFECTED BY COSMIC RADIATION DEPENDING ON DESIGN
Anywhere in our solar system, once you get there, a robot can start roving over the surface or orbiting the target indefinitely. A human mission has to "dig in" and cover themselves with some meters of radiation shielding if they plan to be there any length of time.
BENEFIT OF HUMANS - DECISION MAKING
The main advantage we have are that we can make quick accurate decisions to deal with unexpected situations. However, there is nothing usually that a robot on an interplanetary mission has to respond to instantly. Most robotic emergencies e.g. during landing on Mars happen too quickly for a human to respond anyway.
Given enough time, a robot on Mars or anywhere else in the solar system can handle just about anything, relying to a large extent on decisions made on Earth. But it is slower.
So it is mainly a speed advantage that humans have here. Since robotic missions are also lower cost, then especially as robotic capabilities increase, and costs go down further, you can compensate for this by better autonomy, and just sending more missions.
BENEFIT OF HUMANS - ADAPTABILITY
We can't yet build a robot that is as capable as the human hand. But are getting close. Maybe in future robots on Mars will have hands that they can use to repair themselves like a human mission?
Also this advantage is somewhat offset by the need to use spacesuits. The astronauts on the Moon had a lot of difficulty doing even simple tasks like drilling a short way into the surface. Your hands are stiff and clumsy, again due to the high pressure, needed to protect your hands from the vacuum of space. It's like trying to use your hands with your fingers each enclosed inside a garden hose.
A robot designed to drill, for instance, would probably do a far better job of it than a human. And humans may well find that many tasks are done more easily by telerobotics especially with improved technology, in the near future.
They may repair the ISS for instance, in the future, from inside, using telerobotics. More dextrous, and no danger of e.g. drowning in your spacesuit or being hit by micrometeorite during a spacewalk.
BENEFIT OF HUMANS - EXPERIENTIAL
We like to see other humans doing daring missions. More interested in humans going to the summit of Everest than a robot.
Humans exploring the solar system can describe their experience, write poems, do paintings and so on.
However, as we get improved communications, then we can explore the solar system virtually.
Our rovers have a strong emotional appeal also. Experimenters on these missions like Curiosity, New Horizons, Rosetta and the Philae lander, and Dawn to Ceres - often feel as if in some sense they are there themselves. These robots are like extensions of ourselves, like mobile eyes and hands that we can send througout the solar system.
And if we use robots, then everything that comes back can be experienced by everyone, not just the astronaut explorers themselves.
And our senses are adapted to the Earth. We can experience blue skies, and the sea, and winds, and trees directly. We can sense via sight, vision, sound, smell.
Nobody will ever experience the Mars surface in this way, not present day Mars with its near vacuum conditions. Or Europa or Venus or even the Moon. Always you have a barrier of technology, your spacesuit, you look at it through a visor. And your eyes are not adapted to those conditions. Too much contrast in case of the Moon. In case of Mars, everything a dull grayish reddish brown (the images we see are hugely digitally enhanced to resemble a landscape illuminated by sunlight so that human eyes can interpret them).
So given that our senses are not adapted to these places, we may get our best and most direct experience of them through telerobotic explorers and our unmanned spacecraft.
YAWN EVENTS
The appeal of sending humans to space gets less as it becomes more routine.
The first mission of humans to the Moon was of great interest, fifth and final mission to the surface, though it was the most interesting of all for scientists, was something of a yawn event for most of the general public.
While robots continue to have an appeal. Because they are there for the science and exploration, the focus is always on what they can discover. And that gets the public engaged in the discoveries - probably more so than for a human mission where the human interest angle is the main thing that will get publicity. And science and exploration and discovery is something that continues almost indefinitely.
HUMANS HAVE A ROLE
So, I'm sure humans have a role to play. We have advantages that make it worth while having humans "on the spot". Many of those at present for special situations where humans are needed. And also as explorers and adventurers, the human element of humans out there exploring the solar system has an obvious appeal.
These advantages may become less as our robots get more capable.
But at the same time we may have improvements in life support, be able to send larger masses into orbits, and find ways to support humans in environments where at present it is impossible because of the hazards or for planetary protection reasons.
So, I'm not saying that we should explore the solar system purely robotically.
But we can do a huge amount with robots, as our partners in this exploration of the solar system, and as extensions of ourselves as our eyes and hands and senses on remote moons and planets.
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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