All these worlds are yours except Ceres. Use them together. Use them in peace.
Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds
51–60 of 264 posts
Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds
#52spaceX when? 2048?
Somewhat related I saw it’s going to take NASA’s new Perseverance rover about 7 months to get to Mars and it’s traveling at something like 25,000 MPH. Since NASA had to take the planetary orbits and launch timing, etc. into account I’m assuming that’s the fastest ideal velocity for the rover but not necessarily the fastest possible. So I guess my question is, given that Ceres is so much further away than Mars, what’s…
Faster is normally not all that important: it's much better to save fuel and send more stuff than to get there a few months earlier. Fuel costs vary roughly with delta-V, the total amount you have to accelerate or decelerate your spaceship. Because of the tyranny of the rocket equation, they aren't linearly proportionate to delta-V, but in general, if it takes more delta-V it's going to be harder and more expensive to send a spaceship there.
Here's a map of the solar system by delta-V [0]. Good news is it's roughly equally difficult to get to Ceres as to get to Mars! It's further away, but it's smaller which means less decelerating when you get there.
For your actual question...you can get faster routes with more fuel. We're pretty close to the limits of how big a rocket we know how to build and still get it to Mars (or Ceres) with a 2-ton payload (enough for a lander, a rover and a little fuel) using the most fuel-efficient route. If you want to get there faster, which might be important for manned missions, you need a smaller payload or a bigger rocket. Or the most likely solution - you launch lots of rockets and join up the payloads into a bigger spaceship in Earth orbit. If Elon's goal was to make a one-way trip to Ceres as fast as possible, he'd be doing mostly the same as he is now - focusing on being able to build lots of rockets and launch them cheaply.
Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds
#53Earlier quoted context omitted.
The book(s) acknowledges it's made of ice. You can't drink your entire habitat.
All the water on Earth was drunk at some stage wasn't it?
drunk by a human or drunk at all?
I'd suspect that not all water has been drunk at all, but lets cover the human part.
Lets say the average human drinks 3 liters per day and lives 80 years (3 * 365 * 80 ) = 87,600 liters per human.
there have been about 100 billion humans so 100 b * 87600 =8,760,000,000,000,000 liters have been drunk.
there are about this many liters in Earths 5 oceans (source google search): 1,400,000,000,000,000,000,000
Assuming no one has ever drank the same amount of water before, 8,760,000,000,000,000 It sounds fairly certain that not all water has been drunk by a human, even if my math is way off
Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds
#54Is this actually H2O water? I read the article but I am still unclear. I am often excited to hear that water was discovered on some planet or moon but its always a disappointment to learn that its liquid methane or some other liquid that is not actually H2O water.
I think they will usually refer to this as "oceans" or "liquid oceans". The term "water" as far as I know only refers to H2O.
Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds
#55Earlier quoted context omitted.
I always wondered why we are overly focused on the conditions that created life on earth. Arguably it makes sense to see similar conditions lead to life. But do we really know enough to assume that's only way?
Numerous other ideas exist for alien life, but most of them have their shortcomings. It all boils down to chemical reactions and physics. Imagine a universe of only helium. No valence electrons would be readily available, so chances are you are not going to see helium molecules. Lithium, sure, as a metal. Continue examining various smaller (and more plentiful elements). Fluorine? Well, only one slot available, so you…
This was fascinating to read, thanks for sharing! I hadn’t thought about how much harder it would be to create life out of other elements due to chemistry. Had previously believed the chances were small that other life would be similar to us, given so many options. You’ve convinced me that it seems more likely that other life would be carbon/water based as well due to those limitations.
Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds
#56It's not a planet is it? If Pluto is not a planet, Ceres certainly is not either.
Ceres actually has a similar classification history to Pluto, at one time being called a "planet" and then demoted to "asteroid". Later it became a "dwarf planet" when Pluto was reclassified.
Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds
#57Earlier quoted context omitted.
Somewhat related I saw it’s going to take NASA’s new Perseverance rover about 7 months to get to Mars and it’s traveling at something like 25,000 MPH. Since NASA had to take the planetary orbits and launch timing, etc. into account I’m assuming that’s the fastest ideal velocity for the rover but not necessarily the fastest possible. So I guess my question is, given that Ceres is so much further away than Mars, what’s…
Faster is normally not all that important: it's much better to save fuel and send more stuff than to get there a few months earlier. Fuel costs vary roughly with delta-V, the total amount you have to accelerate or decelerate your spaceship. Because of the tyranny of the rocket equation, they aren't linearly proportionate to delta-V, but in general, if it takes more delta-V it's going to be harder and more expensive t…
> It's much better to save fuel and send more stuff than to get there a few months earlier.
Yes. For cargo and probes/rovers. Not for humans. The faster we can arrive, the less supplies are required and the risk of something going wrong while the nearest help is light minutes away is lessened.
> For your actual question...you can get faster routes with more fuel
Not fuel, but more Delta-V. Which may or may not imply on more fuel. Options are: more fuel (rocket equation bites here), less weight, more efficient thrusters, aka higher ISP (see the nuclear propulsion sibling comment).
What this gives you is the ability to use other trajectories besides pure Hohmann Transfers - which are efficient, but slow.
Ideally we would send supplies ahead of time with the most efficient transfers possible, then get humans there as fast as we possibly can. Otherwise this would take a while, around 400 days, one way. So over two years just to get there and back, plus wait time until the next launch window.
Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds
#58Earlier quoted context omitted.
Somewhat related I saw it’s going to take NASA’s new Perseverance rover about 7 months to get to Mars and it’s traveling at something like 25,000 MPH. Since NASA had to take the planetary orbits and launch timing, etc. into account I’m assuming that’s the fastest ideal velocity for the rover but not necessarily the fastest possible. So I guess my question is, given that Ceres is so much further away than Mars, what’s…
Faster is normally not all that important: it's much better to save fuel and send more stuff than to get there a few months earlier. Fuel costs vary roughly with delta-V, the total amount you have to accelerate or decelerate your spaceship. Because of the tyranny of the rocket equation, they aren't linearly proportionate to delta-V, but in general, if it takes more delta-V it's going to be harder and more expensive t…
Whoa! Thanks for the awesome answer and the map! This blew my mind:
> Good news is it's roughly equally difficult to get to Ceres as to get to Mars! It's further away, but it's smaller which means less decelerating when you get there.
As someone without any background in science I only ever hear about the journey to moon and mars so it’s super interesting to eyeball the marginal difficulty of getting to different planets on that map. Thanks for sharing!
Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds
#59Earlier quoted context omitted.
All the water on Earth was drunk at some stage wasn't it?
I suspect that isn't true, but it is an interesting question. There is a lot of water on the planet, some of it spends long periods locked up out of reach of drink ability. I would guess that at most water has been drunk multiple times, but that there is some miniscule a fraction that moved between icecap, permafrost and deep water table and has avoided being consumed by an animal since it arrived on earth. I would b…
There is a related interesting observation that every breath you take contains on average one molecule that was breathed out by Julius Caesar in his dying breath:
https://www.sciencefocus.com/planet-earth/are-we-really-brea...
Re: Planet Ceres is an 'ocean world' with sea water beneath surface, mission finds
#60Earlier quoted context omitted.
I always wondered why we are overly focused on the conditions that created life on earth. Arguably it makes sense to see similar conditions lead to life. But do we really know enough to assume that's only way?
Numerous other ideas exist for alien life, but most of them have their shortcomings. It all boils down to chemical reactions and physics. Imagine a universe of only helium. No valence electrons would be readily available, so chances are you are not going to see helium molecules. Lithium, sure, as a metal. Continue examining various smaller (and more plentiful elements). Fluorine? Well, only one slot available, so you…
This is so non esoteric. I can't remember who said it but I'm reminded of the old saying: "if you can't explain something to a high school student then you don't understand it". You certainly understand it and I certainly appreciate you sharing your understanding in such an accessible way, thanks.