Human missions to Mars in doubt after astronaut kidney shrinkage revealed
‘An astronaut could make it to Mars but they might need dialysis on the way back,’ scientist warns
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“You can’t protect them from galactic radiation using shielding, but as we learn more about renal biology it may be possible to develop technological or pharmaceutical measures to facilitate extended space travel.”
I wonder why
If you're asking about the shielding, probably the mass required for materials that are generally used for radiation shielding. If the craft is built terrestrially, the amount of energy necessary to launch would be insurmountable with current chemical rockets.
Now, if the craft were manufactured in space (and forming of the shielding materials were practical in low-G), the problematic materials could be shuttled up over time, making it a non-issue. This would, of course, also mean that the craft could not be used for re-entry and would require landing craft. And there's all the logistics challenges (supplying air, etc). Probably though the direction that will be necessary for long-distance space craft.
That's seems a lot different from "can't be."
Yeah. I think that they are simplifying a bit. For practical purposes, for the foreseeable future, it is a "can't be". There is a lot of work and research that would be necessary to get an orbital shipyard in place. As someone else mentioned, the current state-of-the-art space station is effectively little more than rocket body segments with extras (solar panels, etc).
It's much easier for me to say "this is what we would need to do" than to actually do it. We have the technology to build a space station. We don't currently have proven technologies to refine, cast, forge, and extrude metal in microgravity and hard vacuum. We don't currently have proven technologies to manufacturer space craft out of components in microgravity and hard vacuum. And those are just a handful of the necessary things that we know - there are a bunch of unknown unknowns.
So, technically, yes, it isn't a "can't be" but, at this time, it may as well be.
My company worked on the ISS (what's now my team did the electrical power system software), and there really was more to it than that. The way you word it sounds like they took spent boosters and converted them into habitat modules, but that's not at all the way it was. Each element was designed to be brought up in the space shuttle bay and assembled in space (it's the reason for the shuttle's existence). We know how to assemble stuff in space, it's just expensive.
Assembling premade components is one thing, I think he was talking about actually making stuff. If we want effective shielding, that’s a lot of mass, so it would be much easier if we could find it already up there
Maybe if you were going to try to mass produce up there, but the mass of the equipment needed to mine and smelt ore and roll it out into plating would be way more than the mass of the plating for a single vehicle. And that's not considering capturing an asteroid and bringing it into orbit.
Definitely oversimplification and I don't mean to understate the efforts, technology, engineering, and materials that went into the ISS. It's incredible. My main point being just how simple the current state-of-the-art is compared to what would be needed for a sustainable orbital shipyard.
We know how to assemble stuff in space, it's just expensive.
Indeed (ISS being a good example of this fact). The scope here though is beyond just assembly. Also, at minimum, manufacturing of shielding components would likely be necessary in order for such an undertaking to be feasible.
Also means that you have to haul all that shielding to Mars and back, so some combination of bigger engines, more propellant, or just go slower
That’s the benefit of setting up a permanent orbit for transit. You could make a much bigger ship with more shielding and more comfort for a long haul, but only need to get it up to speed once. Then you just need smaller shuttles with good acceleration on both sides
I wonder how much energy would have to be generated to have an active “shield generator” that would positively charge the hull to deflect the solar radiation from it?
The trouble is that solar radiation has both charge polarities in it, meaning your charged shield only deflects half the particles while attracting the other half.
Oh that is interesting. Maybe an oscillating polarity could do it?
First, you'd need to figure out the best "energy shield(s)" for deflecting the problematic radiation. A quick glance shows that there's been some promising research using charged plasma bubbles contained by superconductors. That does not sound likely to be low energy. Then there's other problems like getting telemetry data, etc. Would be awesome if such an approach were proven to work.
Imagine the Co2 released just to get to a space station.
Search Labs | AI Overview Learn more… The amount of carbon dioxide (CO2) emitted by a SpaceX rocket depends on the stage of the launch and the type of rocket:
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Starship
According to Andrew Wilson, an assistant professor at Glasgow Caledonian University, one launch of SpaceX's Starship rocket produces 76,000 metric tons of carbon dioxide equivalent (CO2e), which is a measurement that combines different greenhouse gases into one unit.
Falcon 9
According to an independent study, the amount of CO2 emitted by the Falcon 9 rocket in the lower atmosphere isn't significant compared to the surrounding air. However, in the mesosphere, which is 30–50 miles above Earth, the rocket emits the same amount of CO2 as 26 cubic kilometers of the surrounding air as it travels 1 kilometer.
Other launches
In 2022, the BBC reported that one SpaceX launch emitted around 116 tons of CO2 in 165 seconds during the first stage of the launch. In general, rockets emit around 200–300 tons of CO2 per launch
Despite the downvotes, you do make an important point. In order for space travel to be feasible, efforts are needed to mitigate and reduce the environmental impacts of chemical rockets. For cargo, it could be possible to use electromechanical means of propulsion that may involve acceleration before what a human body is capable of.
Best would likely be a space elevator powered by nuclear and/or renewables. This could greatly reduce the amount of pollution involved in transiting between the Earth and orbital positions.
Plants consume CO2. As CO2 levels increase in the air, plants grow more photosynthesizing material to take advantage of the resource.
Maybe they're looking at SLS numbers and ignoring reusable rockets like Starship? Perhaps it would not be feasible to move a sufficient mass of shielding into orbit using the $2 billion per flight, one time use SLS.
So the monied overlords can escape the mess they made, likely.
I think it's more so they can give false hope to humanity while they continue squeezing the life out of the planet.
Why not both, or more?
They'll die in luxurious insulated compounds of old age before anyone gets to Mars.
Maybe!