A telescope this large could tell us whether any of these potentially habitable planets contain oxygen, and thus, biological processes.
Yet thanks to funding cuts in science the biggest telescope we have in the pipeline right now is one with a 30 metre mirror.
This telescope won't be big enough, and as a result, our failure to push now for bigger sizes is almost certainly going to push back for decades humanity's ability to answer one of the most important questions we face:
Why are we here, and are we alone.
Space-based telescopes are a better avenue. You can achieve much better resolution in practice with a much smaller telescope. There's no atmosphere to block you, and instruments can capture light of any frequency. Cost is the main disadvantage, but delivery of satellites (and maintenance) to space is getting cheaper and cheaper.
All of which is to say that I agree we should be spending more on astronomy. That was your main point, of course. I disagree with the particulars, and think we should be more willing to go to space.
At that point, it will make more and more sense to launch space based telescopes. But... if we wait until we reach that point in the diminishing returns curve, than we lost valuable innovation time/expertise in space based technology.
My hunch is that if we wanted to get the best telescope tech in any given period of time, we should do both and watch as the two types of technologies converge.
That aspect is also much easier in space. Once you get it out there, which is hard...
In comparison, with adaptive optics ground based telescopes have a lot more leeway to be fixed and corrected.
(That said, if astronomical interferometry can achieve the same result as a 100Metre telescope, then let's do it that way! How is less important than making sure we have something in our pipeline within the next decade that can be capable of directly measuring the spectra of exoplanets.)
It has a 6.4m (21ft 4in) primary mirror. Which, from a pragmatics standpoint, answers your question.
Though I suspect mission plans could be drafted for a larger scope yet.
Despite it's impressive number of steps, this does not look like good engineering.
Instead, it looks like a design by committee, with engineers going drunk on complex parts coming together rather than dumbing down the unfurling of this telescope down to its most basic possible mechanism, with the fewest moving parts possible (where failure is chronically always possible).
Seeing how overcomplicated this is, it's no surprise it cost $10 billion to build.
You're looking at a high-precision instrument, that's being fit inside a distinctly finite space and mass budget, that will have to operate for years (possibly decades), and which is beyond reach of any conceivable service mission for a very long time.
Movement, thermal control (the Webb operates in the low end of the visible spectrum, through the infrared, so its temperature itself is critical), alignment, and drift, all matter.
And every piece of equipment has to be tested and trialed to the maximum extent possible.
Yes, it's a bit Rube-Goldbergish, but then, so is the specification.
I wonder if you could make one with a few bits of lens that fold out? They'd have to be positioned more accurately that one wavelength of light (to ~100nm say or a 10,000th of a mm) which is tricky on earth but might be doable in space where you don't have gravity making things flop?
This is because most of society is still struggling with day-to-day tasks like getting housing, clean water, reliable food, healthcare and dealing with physical conflicts.
Even people rich enough to not be stuck in the short term future have to be concerned with near term risks like political destabilization countries and climate change.
So it's hard to rush to do something like this as a society when we are already rushing to solve acute issues.
Only the most pathetic hacks would argue that we are the worse for having invested that money to push the bounds of exploration.
At a point, there are 6 billion people on the earth, and there will always be _some_ problems unsolved, whether that is because a few countries are trying to collapse, or because we have found new first-world problems to agonize about in the US.
It's a question of whether we will spend 10x the cost to solve the last 10% of those problems, or spend that money moving forward as a civilization.
Had we put the same resources into solving other more earthbound problems would we be better off? Maybe we could have developed a better, standard, safer nuclear power plant design and could have left coal and oil behind 30 years ago. And we would not be discussing climate change or at least not the idea that it was man-made.
You might, for example, instead point out that even extravagant space budget proposals are a drop in the bucket compared to military spending.
Once you resolve the issue of poor political leadership, the problem basically solve itself as money and investment engender a positive feedback loop that take care of itself.
The Apollo program was part of the space race against the SU. See my comment about conflicts motivating people to invest in this stuff.
You could (more or less) translate the fascination of the moon landing into an excuse for less reliable housing and so on in the 60s. You can't do so today.
Of course, you do realize that statement could also read: "When we ran the Apollo program, the world had less reliable housing, less clean water, less reliable food, worse healthcare, and more physical conflicts."
Neither of these statements are particularly good at answering the question: How much do we gain by investing money in space exploration versus something else?
There's more than enough money for both. It's a lack of political will that holds us back.
It's been nearly 100 years since anyone struggled with that in the West. Nobody's expecting Eritrea to put a satellite in orbit.
Worth pointing out that Ghana just did.
If we waited until we "solve all our problems here at home," as the GP suggests, we'd still be calling to each other from neighboring trees in a jungle somewhere.
You have go to be joking.
Almost every fourth person in the EU still experiences at least one of the three forms of poverty or social exclusion.
Monetary poverty is the most widespread form of poverty, affecting 17.3 % of EU residents in 2015. Severe material deprivation and very low work intensity follow, affecting 8.1 % of the EU residents and 10.6 % of EU citizens aged 0 to 59, respectively.
Today advanced robotic bionic prosthetics are experimental prototypes. In 100 years, people will be arguing that access to bionic limbs should be a universal human right.
The privilege is palpable. That's almost insulting.
Indian here, lot of people in metro cities dont have clean water. Most middle class and rich people use water filter to clean the water in their house. Forget the villages.
"ISLAMABAD: Eighty-four per cent of the population does not have access to safe drinking water in a country where commercial banks posted windfall profits exceeding Rs475 billion in three years, the Senate was told on Tuesday.
Quoting a study, Provision of Safe Drinking Water, conducted by the Pakistan Council of Research in Water Resources (PCRWR), Minister for Science and Technology Rana Tanvir Hussain said only 72pc of water supply schemes were found to be functional, and 84pc of those had supplied water that was not fit for consumption."
This article was published March this year. Maybe the report in question was alarmist, I don't know.
In case dawn.com isn't a reputable source, here's a number of other articles covering it:
This one has a slightly different focus, and also links to reports claiming the same agency has found contaminations in bottled water too:
Here is the agency's actual report on Punjab province, with a quote below:
"The outcome of the survey conducted in the domains of 21 districts of the Punjab province,
has revealed that water supply schemes are providing piped water supply for drinking
purposes to meet household needs and for other multiple uses to an enumerated population of
19.017 million persons on 2408 surveyed water schemes. The survey has however, summed
up that the performance of these schemes in terms of providing water in an adequate quantity
and of safe quality, is extremely poor. This inability and inefficiency may be scaled from the
fact that 35 percent of the schemes are presently not functioning. As a result, nearly 61
percent of the total enumerated population remains unserved by the water supply schemes.
More alarming situation is that 88 percent of the functional schemes are providing unsafe
drinking water to the consumers. It is also notable that, on province basis, the average water
charges per scheme figure out to Rs. 64 per month. "
"For Pakistan’s majority, the main source of drinking water is groundwater. The most common instrument for extracting groundwater in rural areas are the hand pump and the motor pump. Hand pumps and motor pumps together provide 61 percent of households with drinking water; in rural areas this percentage rises up to 70. "
"In 2015, 91% of the population had access to an "improved" water supply. This was 94% of the population in urban areas and 90% of the population in rural areas."
E.g. if you have a well or running water, and no alternative, you use it, because no water is far worse than bad water. And most of the time chances are it'll be ok.
That makes it easy to conclude that it's probably safe even when there are flaws in the supply that can quickly render it unsafe or that makes it unsafe for sustained consumption.
E.g. arsenic leaking into the supply won't kill you from a drink here and there - arsenic is difficult to kill with, because too high concentrations makes you puke it up - but sustained ingestion of smaller doses may have severe and lasting health effect and may ultimately kill you.
(Arsenic is "interesting" in that a lot of arsenic contaminated water from pumped wells in developing countries is a result of inadequate testing in the rush of upgrading water sources from surface sources prone to bacterial contamination - as such, a lot of those pumped sources may in fact still represent an improvement, but in some cases also still represents a severe health risk)
Overall there's a great deal of progress in securing basic safe water supply. We're just not there yet. Even many developed countries regularly run into water supply issues.
It is clear to me that the purpose of Earth-life is to spread and assimilate all matter that it may encounter, and the purpose of humanity is to build and launch Earth's reproductive spores.
If we are not alone, those other guys had better have some good antibiotics, because we're coming. Right now, it seems like we'll be moving at just a small fraction of c, but slow and steady can still win a race with only one contestant.
The important question is therefore "Once we're all dressed up and ready to go, whats our heading?"
So with respect to telescopes, would it be better to invest that in the ships, and simply launch toward any random nearby star, to be surveyed by the breeding population en route over the next few centuries, or would it be better to sacrifice a ship or two in order to send the ones we do build toward more promising stars?
How about we first at least try to understand life on Earth? We are definitely not alone, there are other conscious beings on this planet. After decades of studies we still have no idea what a humpback whale's song means. Bottlenose dolphins have at least 2 if not 3, sound generating mechanisms that could work simultaneously. The amount of information that can be encoded is enormous. Yet, we are still to learn what a single dolphin's call means. We know the function of some meercats' calls or praire dogs' calls, but despite 60 years of research we are yet to decode a function of at least one dolphin call, let alone something more complex like beluga chatter or a humpback song.
I don't follow. You could say the same thing about any Earth-bound phenomena. There is an endless supply of interesting things to study on our planet. There's also an endless supply of space exploration waiting for us. To pick one to the exclusion of the other seems very shortsighted, given that we don't know what we'll find in either place.
Seems like pursuing all avenues of exploration is the best way to move us forward.
Also, what would the effect of the atmosphere be in such a large telescope? would a bigger mirror increase or decrease the effects of Earth's atmosphere for these kind of observations?
Why not a 100 Meter Telescope? Cost and engineering. With these retro reflectors getting so big, you have to worry a lot about thermal expansion and differential levels of it across the whole surface. Also, the structure to hold it has to be monitored really closely in real time to make sure the calculations are accurate. It's not easy. Also, with modern adaptive optics, you'll have apply all the little piezo-motors across the entire surface which goes as the square of the radius, so costs go up geometrically (plus about 15% more for each doubling in surface area due to cabling, power issues, larger facilities with thicker steel beams, more janitors, etc.). If the TMT costs X, then the 100-MT should cost about 11X, and with the 15% doubling factor, its ~15X for only a 3X increase in radius.
The Thirty Meter Telescope cost $1 billion. So the 100 Metre Overwhelmingly Large Telescope would cost ~$15 billion using your ~15x multiplier. That's large, but for perspective: The F-35 fighter jet program cost $168 billion.
Like with the Large Hadron Collider, if the extra cost means the difference between being able to crucially measure the atmospheric spectra of nearby exosolar planets and not being able to, then the extra cost is worth it.
I'll take getting definite answers to humanity's most pressing questions, over new tools for killing people, any day.
15 billion (as per a sibling comment) sounds like a lot, but relative to other, IMO not so important things like said plane, it's not that much.
However I wonder if it would be worth it or if that money would be better spent creating a Hubble replacement for example.
Why do you need to see a habitable planet soon? If you can't survive that trip, it means almost nothing.
Once we find a good target, the Breakthrough Starshot program is one example of a promising project that could get us results within our lifetime.
This, or a similar concept, is hoped to be in the upcoming National Research Council decadal survey which recommends astronomical priorities for the 2020s. Current designs require as little as 4 meters.
Stability is one advantage of space telescopes. Integration times for spectral characterization can run into days.
We know what technology we need to build. Why must we wait a full two more years for a report to get finished before even beginning funding proposals on which path to pursue, before beginning any construction or engineering?!
None of us are getting any younger. I know this is complicated technology to build, but contrast how fast technology moves in the valley compared to this, and you can see the ways in which NASA could really use a bit of startup hustle... (like back in the 60's, when NASA engineered and landed people to the moon within a decade.) There just appears to be no sense of urgency at all.
The trade studies are highly complex (how big the aperture is, how long the mission is, how much propellant is needed to slew the spacecraft, what the yield will be in terms of number of spectral characterizations, whether you need an external star shade). The star shade, if needed, would be a separate spacecraft.
General comparisons to "how fast technology moves in the valley" are not specific enough to benchmark what's needed for this rather unique mission.
It would be fun to see part of NASA run on design/execution challenges. Have 5000 postdocs on salary, then offer a ($1B-X) bonus for the team which designs and launches a space telescope for X.
Using the sun as a gravitational lens would be pretty sweet.
I have a feeling we will have some more tricks to play with E&M locally before we can go to space on that scale though.
edit: My own semi-blind musing has made me curious:
metamaterials for super-lensing: https://arxiv.org/pdf/0905.0263.pdf
entanglment enhanced microscopes?!: https://arxiv.org/abs/1401.8075
(@shpx linked to this quantum stuff before me, by the way)
We certainly can't visit these places for quite some time though.
ESO is not going to give up, and they don't have to fight with science-deniers for funding, so there's not much to worry about yet.
An old friend once said, "We're all alone together". I replied, "I can't handle that".
"Well, can you handle this?", he said, with arms spread wide to the sky, laughing.
Not to be anti-technology, but it may well be that the answers to life's questions depend on nothing.
Bill Gates also made it painfully clear that he wants his money to go to issues we can resolve right now here on Earth like renewable energy, clean water, fighting disease, etc, which is why philanthropists like him avoid funding anything space-related. They want to witness the fruits of their investments within their lifetimes.
Easy: Marketing the brand name. Imagine a rocket with Google painted on the side on the evening news. Updates on the construction and progress, all mentioning Google. Google setting up a Google Center that collects all the data coming down. Every discovery has Google's name attached to it. Etc.
Consider this: Let's assume group A and group B both follows a bell curve in terms of abilities. Let's assume they're not equal. Maybe group B is shifted so that only 3% of group B can compete with the top 10% of group A, for example.
Now, if you hire exclusively from group A, and you due to competition for resources end up hiring from the top 20% of group A, you are losing out - there are then substantial numbers of candidates in group B that outperform people you are willing to hire from group A.
That is a non-emotional explanation for why diversity is good unless we're in a world where current distribution already accurately reflects merits:
Even if you assume that there are substantial differences in abilities between genders or races, unless you can consistently rule out that anyone in these groups are able to compete on abilities, creating an environment that is non-inclusive will leave your competitors with access to better people than you have.
The best way of ruling that out, if you believe these groups have different distributions of abilities, is to carefully control for biases and recruit on ability.
Now, if you mean quotas where metrics of abilities are ignored in favour of hiring people belonging to specific groups, then that changes the issue, though sometimes such quotas can also be justified if you have reason to believe the metrics used are flawed.
E.g. in the UK private schools tend to outperform state schools on A-level grades (equivalent, roughly to SATs / high school diplomas; used for university applications), but the conditions a top student in state school works under also makes it likely that their grades under-represents their learning abilities vs. private school students under equivalent conditions - differences in class sizes and available resources does make a difference in exam performance, and if you can correct for it, it makes sense to do so. If you don't, it may make sense to use quotas to ensure you safeguard your ability to skim the best candidates from these groups.
Incidentally, taking more students from state schools would on average be likely to take more black students, for example.
My (black, female) ex is on the diversity board of a major investment bank's offices in the UK, and is struggling with exactly this: The bank in question almost exclusively hires from a set of private schools where white men dominates, and sees "diversity" as being about attracting the few black people and women from those schools, rather than hiring by ability without looking at which schools the candidates are from, which would let in far more women and black people.
This is before taking into account other factors, such as positive PR with customer groups that hold increasing importance.
In other words, there are substantial cold, hard, emotionless reasons to push for less biased hiring, and the proponents of most diversity programs believes that these will provide more diversity through meritocracy, not despite it.
Not everything a company does is always related to medium-short term returns and most shareholders probably get that.
To me that question is high on the list as well. And preferably more so.
If they are a few hundred years ahead of us technologically they know about us and don't care. If they are a few hundred years behind they won't be able to receive our transmissions. I know science nerds need a wondergasm, but until we get some decent deep space propulsion technology it doesn't freaking matter. Seriously, except for some cool TV shows what tangible benefit had deep space cosmology brought us in the last 40 years?
No, seriously: https://en.wikipedia.org/wiki/Overwhelmingly_Large_Telescope
What do you mean by this?
So while discovering life on another planet wouldn't answer exactly "why we are here", it would go a hell of a long way in shaping our answers to that question.
That is to say, that arguably "Why are we here" is the only question of more significance than "Are we alone?"
If this telescope can answer the second most important question to humanity, that's pretty good.
Man, I too wish we had more money for large scale scientific endeavours, but I am not flabbergasted that we don't; I can see perfectly why not.
By another commentators estimate, the 100 Metre Telescope would cost ~$15 billion to build. In comparison the F-35 fighter jet program cost $168 billion, and in 10 years the U.S. will spend roughly $5.5 trillion on its military.
The point is to grab perspective about how achievable these goals are, using money that's being wasted in such large supply right now on tools to kill people.
If we found strong evidence of life existing on another exoplanet (due to finding oxygen in the emission spectrum of an exoplanet's atmosphere), it would be a game changer. A story of the year, and influence the outcome of the rest of our century.
It would compel, very likely spending on space probes and exploration to go way back up to levels seen in the 1960's or even higher. That was a time when we had both robust spending on space exploration and social programs...
If we had thought the similar way in case of microscopes, we would still be dealing with pandemics cluelessly about how to prevent them.
Sometimes thinking long term can solve a lot of short term problems.
However, we have a good prior on the inclination of these planets, because we know the inclination of the dust disk around the star (https://www.scientificamerican.com/article/tau-ceti-s-dust-b...), and it is likely the planets are at a similar inclination. Because the disk isn't edge on, the planets also likely aren't, and won't transit.
"In astronomy, a transit or astronomical transit is the phenomenon of at least one celestial body appearing to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point."
You have to assume it has examined this close neighbor thoroughly.
I'd expect it's easier to measure at the brighter stars. Maybe calibrating the instrument for the weaker stars makes it "overload" for a really bright ones?
If we could hit 50% speed of light we could do a fly-by mission in ~25 years. Then another 12 years waiting for the data. Honestly, ~37-40 years isn't bad for an interstellar mission. Remember the Voyager program
has been going on for that long! So we already have experience with long space missions.
Sadly it's going to likely a require 100metre telescope mirror or larger, and current science funding only has a 30metre telescope mirror in the works. The 100 metre telescope was cancelled. https://en.wikipedia.org/wiki/Overwhelmingly_Large_Telescope
The answer is at our fingertips, yet the science community can't get the money to build something that would be a fraction of what F-35 fighter jets cost.
What the !@#$ are we doing as a human race...
I thought you needed to be capable of directly imaging the light of an exoplanet in other wavelengths in order to do that.
What is SKA? Super K? Aperture?
It's not quite enough to build the instruments. We have to fund the ongoing science, too. Philanthropy does play a role here, too, of course: endowments for academic research, but generally not as inspiring as making Very Large objects.
Anatomically modern humans have lived on Earth for 200,000 years, and the creatures we descended from have lived on Earth for 541 million years. Stuff as dumb as the moon cycles affect us. How are we going to live somewhere that isn't exactly Earth?
I understand that the military is partly a large welfare program which doesn't compete with private enterprise due to different technologies and classified material, but I wish there was a movement to invest more of that time, money, and energy on basic research, climate change, energy technologies and space exploration. It's a hard sell though because I suspect that these technologies would compete heavily with established businesses.
- large part of budget is salaries and pensions.
- looks like %budget for military is lowest it's been in 20 years, (in 2015) 16% https://en.wikipedia.org/wiki/Military_budget_of_the_United_...
The point is the size of it, not the trendline.
NASA got 2-4% to go to the moon. Right now it's at 0.5%. Imagine how much space they could do with 8%.
50% for the military? All the figures I can find say it's 16% of federal spending.
Edit: As others have pointed out. OP may have been suggesting we redirect 50% of the military budget to space not that the military budget is 50% of the national.
Entitlement programs like SS and Medicare/Medicaid are raised on a separate tax (you can see it on your paystub), and have zero discretion in how they're spent. It's determined by statute and is automatic, not part of the budget process, and the money never really mixes with the rest of the federal budget.
If you take those out, and take out interest payments which we also don't have much choice in, military spending is 54% of the money that's actually at issue when Congress makes budget decisions.
Astronomy funding stagnates when its about rocks and geology. Bring real evidence of aliens into the mix and you've defined humanities focus for the next century.
We could develop our own alien life right on Earth within that timeframe.
E.g. Breakthrough Starshot can get us to many exoplanets within 20-30 years: https://en.wikipedia.org/wiki/Breakthrough_Starshot
It is ~4 ly away. If you're willing to go ~10 ly, you get 6 more stars to look at. And it gets far worse from there.
So that's 7 or more planets. That's many.
I agree with the text of your message; it just isn't an appropriate reply to what I said. In fact if such a thing was discovered I'd say all bets are off in terms of the response.
People will get more sick, they will need more attention. But that doesn't mean that it is not possible.
Umeå is a Swedish city with a population of over 120,000. January has 33 hours of sun, while June has 286. That's fairly different from your usual place to live. But the city is a completely normal city. You need to go to more extreme situations to get a city that needs extreme changes.
So yes, there are challenges. People living in zero gravity has a lot of health problems, for example. But the most similar the planet the fewer problems there are. And it is cheaper and easier to move there.
In other words, you'd almost definitely have to send a generation ship. Which means you'd have to have already figured things like artificial gravity, giving birth and raising children in space, etc. It wouldn't be too hard to imagine taking earth values for day/night and gravity, and then gradually over 50 years adjusting them so that, by the time you arrive, you'd have acclimatized to those values on the new world.
Also, nuclear sub crews live 18 hour days, so it's definitely doable.
 disclaimer: I didn't do the math, i just googled the tables.
Divide the elapsed time in the stationary reference frame by the dilation factor and you get values that roughly agree with yours.
Some kind of sleep hibernation tech, might make it possible to kind of stop or dramatically slow down aging.
Maybe someone knowledgeable in this space can tell me, but is a planet's atmospheric pressure reliably proportional to its mass?
One common solution in SF novels is for aliens to be in an atmosphere suit, typically very high tech (thin and floating). In extreme cases, the suit would encase the whole body in gel fluid and also inject it into lungs and other orifices to withstand pressures from different gravities or ship acceleration.
In essence, you need a lot of tech to allow diverse aliens to spatially co-exist.
Edit: All of this ignores food. Typically, stories solve that with some kind of nano-replicator that can make any combination of chemicals safe for aliens to eat.
I feel you on Star Trek. It always kills me that 90% of species in the quadrant is a bipedal humanoid, although they did address this in "The Chase" (TNG:S6E20). But I digress.
I m a firm believer that non-natural, non-random life forms will dominate the space exploration including robots, augmented humans, bio-robo hybrids and Supra and sub swarms of those.
No. Proof: Venus/Earth.
So that particular aspect is not something to worry about.
To further your (good) point about gravitational and diurnal differences, it is worth also considering the experience of native americans in the face of novel (to them) micro-organisms brought in by europeans.
These diseases were not from another solar system and they were related to animals that had local analogs ... and yet they were devastating (up to 90% mortality in some places) to the native population.
On another planet the bacteria, viruses and fungi (not to mention the potential discovery of previously unknown biological primitives) would be completely novel to us.
I wouldn't be shocked if there was 100% mortality outside of containment/quarantine after a week or two.
EDIT: On the other hand, imagine if we found that our genetic code did contain information related to what we found offworld ... wouldn't that be fascinating ...
> microscopic dust
Found on earth! I change my HVAC filters regularly.
> and a complete lack of nature
There's plenty of nature on Mars. Not much life, but we'll bring that with us. I'd suspect early colonists will have more plant life in their quarters and living areas than your average NYC resident.
> or Internet
I'd fully expect a solution along the lines of Netflix's edge caches for this by the time we're seriously considering building a base. Daily snapshots of Reddit, StackOverflow, major news sites, etc.
People living in large urban centers are essentially 100% disconnected from any sort of natural day/night light cycles, but they still manage (with, admittedly, some negative health effects). Same deal with gravity; the human body can support people who way 2x the average for their demographic, so I don't think 10% different gravity will matter much.
In the worst case, we could probably do genetic modification or just use exogenous hormones to help adapt to weird sleep cycles.
This isn't the same thing at all.
Growing up in a high gravity environment would definitely alter your growth. We've also seen that it leads to fluid imbalance, cardiovascular issues and general fatigue
Sounds pretty much the same as obesity to me.
to conditions on Earth
"The outer two planets around tau Ceti are likely to be candidate habitable worlds, although a massive debris disc around the star probably reduces their habitability due to intensive bombardment by asteroids and comets."
In such planets, the most habitable zone is around an equator like region where the light and dark regions kind of merge to produce a reddish sunset like hue all through the day. I think one of the planets that Kepler discovered is like that. Life would evolve to absorb these light wavelengths. So for instance plants would all look black. Nova has a great episode on these exoplanets. https://www.youtube.com/watch?v=5HZsFMqqGJo&t=793s
Project Orion is awesome and I am a big supporter. Unfortunately people won't stand for the thousand some odd nuclear bombs it would take to get the interplanetary version out of the atmosphere.
Because it is so massive, building it in space also poses a problem unless we capture a iron meteorite and bring it back or mine/build it on the moon. Both of which we should really do because it would be by far the fastest ship we can build right now.
I realise it's like 4*Australia^3 in volume and mostly iron, but seems like small changes could have huge impacts.
Because it doesn't use conventional chemistry the presence or absence of chemicals, like ambient oxygen wouldn't change the output (like it might for a fuel air bomb) but their their properties might change it. Air will provide some resistance and fluoresce at high enough temperatures. I am curious how big this effect would be though. Debris leaving a nuclear explosion in space would only stop when it hit something and that I think is the biggest flaw with the Orion motor.
If the motor and fuel can be designed so only particles are emitted and somehow ensure that no bullet size fragments are ejected then it seems likely it could be made safe in a practical sense.
That said they at least all seem like solvable problems given enough time and resources.
Build something like the TransAmerica Pyramid (without the two white flanges) and put the motor(s) where the foundation would be as to make the building fly like a rocket. Put the motors on at one G and you get artificial gravity, a slim profile and damage equally distributed along the bulk of the ship and most collision will happen at extreme glancing angles.
Stop off near a comet and melt large boulders of ice to the hull. If the outer hull is tiered whipple shields there will be plenty strong and will serve as mount points for the ice. Run simple heating element through it and simplify the installation of ice as ablative armor.
Have all of the storage on the ship be on walls, cabinets, netting, shelves, etc... and bolt all the furniture down. Because when you aren't accelerating you will have no gravity.
When you want to stop, turn the ship around (using reaction wheels or attitude jets) and blow your engines at the target at 1 G to slow down for the same amount of time you burned them to accelerate. This will create artificial gravity again in the same direction you were experiencing it before because you changed the direction of thrust the same amount you changed the orientation of the ship.
You have a nuclear explosion clearing crap from in front of your ship as you slow down, not as safe as the ice, but presumably your engine(s) is tough enough to withstand a nuclear blast.
Isn't turning the ship at those speeds nearly impossible? You'd either have to slow the entire ship down first (the whole idea) or burn a ton of fuel to turn it while accelerating at a percentage of light speed, while avoiding debis and the spaceships engines explosions. I believe this is why scientists researching this prefer magnetic sails as a means to slow down. Or maybe an alternative engine scheme that doesn't require doing a 360 turn.
The feathers/fletching on an arrow produce more drag and the the arrowhead is dense and moves the center of mass really far forward. As air passes over it the center of mass is pushed back least and the part with more drag are pulled back more.
In space there is no air so rotating the ship is trivial. Consider comets or planets that are constantly revolving. Also, don't confuse turning with changing velocity and direction or travel.
In my previous example the ship would stay in constant motion even though it is turning a 180 degrees. The actual turn could be done with rockets or reaction wheels and by spending very little force to do it.
On the serious side, we only need antimatter and the drive problem is kind of solved (yes, I might be the one in the good enough ship :)).
If it got down under a year maybe, but predicting what might happen if we invent FTL is a job for people who are deliberately making things up.
On the other hand, they would probably have beer.
The Expanse series is predicated on the development of a reactionless drive that converts energy directly into thrust without expenditure of mass. If such a technology existed, you could get going pretty fast just motoring along at a constant 1-g acceleration, and have "gravity" too.