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Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

theguardian.com

231–240 of 264 posts

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#231
post #119

Earlier quoted context omitted.

Would evolutionary timelines or cycles be slower in an overall colder planet? (Thinking of those interactive diagrams for temperature on the kinetic energy of molecules zooming around in closed space)

Well, at least that seems to be the case on earth. Creatures from the cold deep sea have slower life cycles than creatures in the tropics.

Shorter life cycle sounds like faster evolution actually.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#232

Nitpicking, I know, but to call it "Planet Ceres" in the title is more than a bit wrong. This is a dwarf planet at best and is also often classified as a really big asteroid (the only one in the asteroid belt that's rounded by its own gravity). If even the much larger Pluto can't get the "Planet" title, Ceres hardly deserves to be called that in a headline from a major newspaper.

Funny enough the headline now reads "Dwarf planet Ceres ..."

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#233
post #66

Ceres is a good place for a lander and rover then. Might be some action there. Face it, Luna and Mars are boring, low-value real estate.

You think Mars is boring?? I think it's exciting. The more evidence we find that life may have existed there, the less valid our mythical creation stories of earth as the special only recipient of God's hand. Mythology is fun but it's given too much power in certain societies, while science and truth are devalued in turn.

You might be interested in this line of reasoning, why finding life on Mars might in fact be counter to the long-term survival of humans.

https://www.nickbostrom.com/extraterrestrial.pdf

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#234

Earlier quoted context omitted.

We'll eventually get to the point where Starship-like rockets only ferry people, cargo, and, maybe, propellant to LEO for transfer to spaceships that don't need to go deep into any gravity well. These ships will then take you to orbit around your destination so you can board another shuttle to the surface.

That would be massively inefficient for travel to Mars, because you can Aerobrake to land and make fuel on Mars for your return.

You could probably aerobrake to get into orbit instead. But eventually it might make sense to build ships that are never supposed to touch atmospheres, or only upper layers. Some design constraints can be relaxed then.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#235

Nitpicking, I know, but to call it "Planet Ceres" in the title is more than a bit wrong. This is a dwarf planet at best and is also often classified as a really big asteroid (the only one in the asteroid belt that's rounded by its own gravity). If even the much larger Pluto can't get the "Planet" title, Ceres hardly deserves to be called that in a headline from a major newspaper.

I don't know what the criteria are for defining a planet (and I know that there is a great deal of controversy), but "rounded by its own gravity" seems like a good dividing line to me.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#236
post #229

Nitpicking, I know, but to call it "Planet Ceres" in the title is more than a bit wrong. This is a dwarf planet at best and is also often classified as a really big asteroid (the only one in the asteroid belt that's rounded by its own gravity). If even the much larger Pluto can't get the "Planet" title, Ceres hardly deserves to be called that in a headline from a major newspaper.

>>If even the much larger Pluto can't get the "Planet" title Damn you Neil deGrasse Tyson Pluto is and always well be a planet

what an odd hill to die on...

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#237

Earlier quoted context omitted.

That would be massively inefficient for travel to Mars, because you can Aerobrake to land and make fuel on Mars for your return.

You could probably aerobrake to get into orbit instead. But eventually it might make sense to build ships that are never supposed to touch atmospheres, or only upper layers. Some design constraints can be relaxed then.

There definitely is a place for Aldrin Cyclers, not soon, but eventually. It’s not to save on fuel, but to provide safer and healthier accommodations for the trip.

How it will likely work is passengers will take a Starship to orbit. It will be refueled in LEO, then accelerate to Mars injection velocity to match orbit with a passing Cycler. It will dock with the Cycler, passengers will switch to the Cycler for the duration of the journey. The Cycler will be much roomier, have better shielding, and likely rotate to provide Mars level artificial gravity. Passengers will have far better work, entertainment and workout options.

Once the Cycler approaches Mars, passengers will reboard their Starship, and it will Aerobrake to land, while the Cycler continues on in its orbit, which returns to Earth. The Cycler never slows to orbit either Earth or Mars, it just coasts between them but occasionally will need fuel for course optimizations.

The only problem is that Cyclers will take 9 months to go to or return from Mars. They will be like large cruise ships. Starship can make the trip to Mars in as little as 3 months, and some will still do that. They will be the equivalent of the long distance direct flight, trading a less comfortable and less healthy trip for a big time savings.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#238
post #167

Earlier quoted context omitted.

True, but in orbit refuelling means 3 or 4 additional refuelling launches, so now your cost per kg is back up to a few thousand $ per kg again. Still cheap for Ceres though.

Yeah, orbital refueling doesn't change the rocket equation unless you can manufacture fuel in space. The only benefit is that you don't need a bigger rocket.

Sort of true. The rocket equation doesn't account for the added weight of lifting the rocket itself, just the added fuel. Multiple launches can reduce the practical overhead, even if not changing the overhead in the limit of 0% rocket mass 100% fuel mass.

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#239
post #236
post #229

Earlier quoted context omitted.

>>If even the much larger Pluto can't get the "Planet" title Damn you Neil deGrasse Tyson Pluto is and always well be a planet

what an odd hill to die on...

Probably depends on your age. Did you grow up with Pluto being a planet? Having to learn about it in all levels of schooling as a planet? Seeing images of all the planets and Pluto is included?

Or did you grow up afterwards and learn from elementary school that Pluto is not a planet so people who still insist that Pluto is a planet seem anachronistic?

It would be like Hydrogen being removed from the periodic table and being told that from now on Hydrogen is no longer considered an element. Would you still try to say that you feel that Hydrogen really is an element, even though you are wrong and Hydrogen is not an element and never should have been included on the Periodic Table in the first place?

Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds

#240
post #236

Earlier quoted context omitted.

what an odd hill to die on...

Probably depends on your age. Did you grow up with Pluto being a planet? Having to learn about it in all levels of schooling as a planet? Seeing images of all the planets and Pluto is included? Or did you grow up afterwards and learn from elementary school that Pluto is not a planet so people who still insist that Pluto is a planet seem anachronistic? It would be like Hydrogen being removed from the periodic table an…

Pluto was a planet when I learned about it in school. I also learned that it was the one that was discovered last.

When they decided to change its status to dwarf planet, I looked up the reasons behind it, read up on the complexities of the matter, and could see the reasoning behind the change.

Then again, I hadn't reached thirty yet. Even in my forties I find it takes slightly more time to change my mind on some things...

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