Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Earth-like planet spotted orbiting Sun’s closest star

nature.com

Post reply on HN
Print view View original

331–340 of 351 posts

Re: Earth-like planet spotted orbiting Sun’s closest star

#331

Post by rnk »

ethbr0 wrote: post #144
T-A wrote: post #56

There seems to be some confusion about the meaning of "within the habitable zone". From the paper (Introduction and Conclusions, respectively) [1]: The habitability conditions of Proxima b, which orbits within the HZ of the star, have been extensively studied (e.g. Barnes et al. 2017; Ribas et al. 2016; Turbet et al. 2016; Meadows & Barnes 2018). On the other hand, the candidate Proxima d orbits much closer to the st…

Here's a good collection of details about the entire star system of Proxima Centauri, including its planets. https://www.star-facts.com/proxima-centauri/ Also fascinating, a relative distance vs time graph of close stars. It turns out we'll have closer distances for 6 in the next 10,000 - 50,000 years. https://www.star-facts.com/wp-content/uploads/2020/08/Neares... Somehow I feel like Elon Musk has a print out of tha…

Thanks for that chart, that site is really worth checking out! There is a ton of cool stuff there, like the nearest starts, when we computed their distances, and other thing.

Re: Earth-like planet spotted orbiting Sun’s closest star

#332

Post by politician »

GoblinSlayer wrote: post #124
politician wrote: post #67

Earlier quoted context omitted.

This is hopeful negativism. - They don't need fusion. A StarShip can deposit hundreds of solar panels and put them on the ground. No, dust isn't an issue because they'll bring a roomba. No, this isn't a joke, NASA martian probes' solar panels were cleaned by a light Martian breeze. - They will be able to become self-sufficient rapidly. They're not going to send 1M tons of cargo to Mars without a deployment plan. Spac…

>They're not going to send 1M tons of cargo to Mars without a deployment plan. Can this happen? I imagine before we can settle on Mars we first should be comfortable flying there, and the latter should be sufficient for asteroid mining. But, right, our technology is just not at a comfortable level yet.

Comfortable comes much later than possible. When it's possible to go, that's the time to go. The early Atlantic crossings weren't comfortable, just possible.

Re: Earth-like planet spotted orbiting Sun’s closest star

#333

Post by ncmncm »

s1artibartfast wrote: post #328
ncmncm wrote: post #317

Earlier quoted context omitted.

McDonald's won't go bankrupt if you elect not to get the large fries. SpaceX would have gone bankrupt several times if NASA hadn't kicked in at a crucial moment.

So they deserve equity for being a critical customer? I still don't follow the logic.

You won't.

Re: Earth-like planet spotted orbiting Sun’s closest star

#334

Post by ncmncm »

mannerheim wrote: post #296
ncmncm wrote: post #295

Earlier quoted context omitted.

We do ISRU all day, every day right here, in the millions of tons. "A stop" is not just useless, but is actively harmful in space transportation. You go, for free, until you get there, and then use up fuel stopping. Starting and stopping are exactly what costs. Stopping halfway makes the whole trip cost literally twice as much.

It's also 'for free' to continue from LEO to anywhere else, but it can still make sense to refuel in LEO rather than launch with all the fuel requirements you need for the mission from Earth surface. The delta v required from LEO to another body is lower than that from Earth surface there. Delta v required from lunar orbit to some non-terrestrial body is also lower than that from LEO, and it could potentially make se…

Refueling in LEO or high earth orbit is fundamentally different, in every single particular, from stopping somewhere halfway.

Until you understand this, everything you say about space travel will make zero sense, and furthermore will deeply embarrass you for long after you finally catch on. You make a fool of yourself by continuing in this vein.

Re: Earth-like planet spotted orbiting Sun’s closest star

#335

Post by e40 »

carapace wrote: post #143
e40 wrote: post #135

Earlier quoted context omitted.

I just finished the book yesterday. I rank it #1 on my all-time SciFi list. I would say A Fire Upon the Deep is #2 and Dune #3.

Really? A Fire Upon the Deep and Dune are masterpieces, yes, but The Dark Forest although good isn't in the same league IMO. - - - - Tangent: Have you read Gene Wolfe's Book of the New Sun ? It's less famous than the books above, but (IMO) it's in the same rarefied company as Dune and J.R.R. Tolkien's work.

I definitely think The Dark Forest ranks up there with those.

I haven't even heard of Wolfe's book. Will check it out, thanks.

Re: Earth-like planet spotted orbiting Sun’s closest star

#336

Post by wizzwizz4 »

mcbits wrote: post #266
wizzwizz4 wrote: post #76

Earlier quoted context omitted.

> We have only recently put a man on the moon, and now we're saying we would be able to detect dyson spheres...? A moth doesn't even have electricity, but it can detect a lampshade. A Dyson sphere is basically a stellar lampshade; we can detect it if the laws of thermodynamics hold, and we're pretty sure they do. (A Dyson swarm is similar, though a bit harder to detect.)

Maybe stars are the Dyson spheres, and their emissions are the waste energy that wasn't worth harvesting.

The spectral signature would be different if that happened. If all of the stars are Dyson spheres, then… maybe our models about stars are fundamentally wrong. But I doubt it; the maths to work out what the signature should be (given the composition) is pretty simple. Take a blackbody, put spectral lines as measured in the lab onto it, then redshift it.

Re: Earth-like planet spotted orbiting Sun’s closest star

#337

Post by mannerheim »

ncmncm wrote: post #334
mannerheim wrote: post #296

Earlier quoted context omitted.

It's also 'for free' to continue from LEO to anywhere else, but it can still make sense to refuel in LEO rather than launch with all the fuel requirements you need for the mission from Earth surface. The delta v required from LEO to another body is lower than that from Earth surface there. Delta v required from lunar orbit to some non-terrestrial body is also lower than that from LEO, and it could potentially make se…

Refueling in LEO or high earth orbit is fundamentally different, in every single particular, from stopping somewhere halfway. Until you understand this, everything you say about space travel will make zero sense, and furthermore will deeply embarrass you for long after you finally catch on. You make a fool of yourself by continuing in this vein.

You can do the calculations yourselves. Refueling in LEO is energetically more costly than a launch from the Earth surface to escape. You will end up using more fuel overall if you launch into LEO vs. if you take all the fuel you need from the Earth's surface in a single launch. If there is a difference, you haven't explained it.

Re: Earth-like planet spotted orbiting Sun’s closest star

#338

Post by ncmncm »

mannerheim wrote: post #337
ncmncm wrote: post #334

Earlier quoted context omitted.

Refueling in LEO or high earth orbit is fundamentally different, in every single particular, from stopping somewhere halfway. Until you understand this, everything you say about space travel will make zero sense, and furthermore will deeply embarrass you for long after you finally catch on. You make a fool of yourself by continuing in this vein.

You can do the calculations yourselves. Refueling in LEO is energetically more costly than a launch from the Earth surface to escape. You will end up using more fuel overall if you launch into LEO vs. if you take all the fuel you need from the Earth's surface in a single launch. If there is a difference, you haven't explained it.

I have, several times, and you have ignored it, several times. Other readers caught on long ago. Only you continue embarrassing yourself.

Re: Earth-like planet spotted orbiting Sun’s closest star

#339

Post by mannerheim »

ncmncm wrote: post #338
mannerheim wrote: post #337

Earlier quoted context omitted.

You can do the calculations yourselves. Refueling in LEO is energetically more costly than a launch from the Earth surface to escape. You will end up using more fuel overall if you launch into LEO vs. if you take all the fuel you need from the Earth's surface in a single launch. If there is a difference, you haven't explained it.

I have, several times, and you have ignored it, several times. Other readers caught on long ago. Only you continue embarrassing yourself.

No, you did not. You have made such false claims as 'If you can't get there without a stop at Mars, then you really, really can't get there with a stop at Mars.' This is a claim that is easily shown to be false by calculating the differences in delta v from Mars to belt/outer planet destinations vs from Earth. You then claimed what you meant was that it takes more energy - but so what? It takes more energy to refuel in LEO than it does to launch a ship from the Earth surface to escape. Basically this entire time you have simply just claimed 'no, you're wrong' without any calculation to back it up, and the few claims that you have made have been ludicrously wrong.

Re: Earth-like planet spotted orbiting Sun’s closest star

#340

Post by ncmncm »

mannerheim wrote: post #339
ncmncm wrote: post #338

Earlier quoted context omitted.

I have, several times, and you have ignored it, several times. Other readers caught on long ago. Only you continue embarrassing yourself.

No, you did not. You have made such false claims as 'If you can't get there without a stop at Mars, then you really, really can't get there with a stop at Mars.' This is a claim that is easily shown to be false by calculating the differences in delta v from Mars to belt/outer planet destinations vs from Earth. You then claimed what you meant was that it takes more energy - but so what? It takes more energy to refuel…

"When you find yourself in a hole, first stop digging."
Post reply on HN