3 ms·

Barely spacefaring. We are like fish on the shore who can survive in the mud long enough for the tide to come back to rescue us, if that.

morkalork 3y ago
That's a pretty good comparison. We go to space but it's a fleeting excursion so far and we haven't yet evolved the necessary abilities to make it permanent
- Charon77 3y ago
  If a planet in the nearest star harbors life form that launched a rocket, would we know?
  - cryptoz 3y ago
    No, we wouldn't know today. But this is knowable in about 50 years or so, if we send probes to ~550AU and use the Sun as a gravitational lens; we will then be able to get high-res (1km resolution?) photos/videos of nearby extrasolar planets themselves. This may be enough to find a spacefaring civilization. (sure, rockets aren't 1km big, but they do leave big traces. maybe we could see that)
    - Qem 3y ago
      > if we send probes to ~550AU and use the Sun as a gravitational lens; we will then be able to get high-res (1km resolution?) photos/videos of nearby extrasolar planets themselves. It doesn't scale well. The probe would be able to observe a carefully chosen extrasolar planetary system in the opposite direction in relation to the sun. If you want to observe a second system, it's necessary to launch a second probe 550 AU in another direction. You can't change targets just by rotating the probe, given its lens is the sun.
      - cryptoz 3y ago
        Oh yeah, I'm aware that you'll need multiple probes - but I imagine we could send 50 or 100 of these things starting in like 20-30 years once some of the required engineering on propulsion systems etc is done. Assuming we have the will and money to send 1, I think we'd have the will and money to send dozens.
    - defrost 3y ago
      As Qem mentioned, and as laid out on page 7 of the source paper: A significant difference of the solar gravitational lens from a conventional telescope is that the gravitational lens telescope is not in any practical sense pointable. For the telescope at a distance F from the sun to be re-aimed to image a new target 1° away, it would have to move a distance of (π/180°)F, which is 10 astronomical units at the minimum focal distance-- a lateral distance equivalent to the distance from Earth to Saturn. This means that, in practice, such a telescope is not able to be repointed. Thus, a telescope at the gravitational focus is necessarily going to be a singlepurpose telescope, with the target of observation selected before the mission is launched. A gravitational focus mission can’t be used as a telescope to search for a target: such a mission must be with the objective to observe a target whose position is already known. Mission to the Gravitational Focus of the Sun: A Critical Analysis Geoffrey A. Landis, NASA John Glenn Research Center https://arxiv.org/ftp/arxiv/papers/1604/1604.06351.pdf https://arxiv.org/ftp/arxiv/papers/1604/1604.06351.pdf
    - p1mrx 3y ago
      That seems like a good match for this nuclear sail concept: https://www.nasa.gov/general/thin-film-isotope-nuclear-engine-rocket/ https://www.nasa.gov/general/thin-film-isotope-nuclear-engin... > The basic concept is to manufacture thin sheets of a radioactive isotope and directly use the momentum of its decay products to generate thrust. Actually it's mentioned at the end of the article: > Novel ability to reach deep space (> 150 AU) very quickly and then continue aggressive maneuvers (> 100 km/sec) for dim object search/rendezvous and/or retargeting telescopes at the solar gravitational focus over a period of years.
zarzavat 3y ago
That’s just because our neighbourhood is so boring in comparison to Earth. Imagine that by some chance Mars was another Earth with a breathable atmosphere. NASA would have been given a trillion dollar budget and we would have been there in the 80s. Instead it’s a dead red rock so NASA gets a small budget and the US spends its money on blowing people up instead. We have the technology to be a spacefaring civilisation but we won’t care until Earth becomes a worse place to be than the rest of the solar system, which is probably never given how bad the other bodies in the solar system are. Most likely we develop Von Neumann probes before we ever get bored of Earth.
- XorNot 3y ago
  I do keep hoping we get lucky in my lifetime and a massive, water bearing comet with slam into Mars and jumpstart the terraforming. Watching a planet which could retain water go from "nothing to oceans" would be amazing.
  - lostemptations5 3y ago
    Evidence suggests Mars had oceans before and they just evaporated due to the thin atmosphere and non-existant magnetic field no? I'm not sure how that would get solved without some active technological solution by humans let's say.
    - XorNot 3y ago
      Over a timespan of hundreds of thousands of years. Which is short in geological terms, but an eternity in technological ones. We would have plenty of time to solve that problem.
    - mjevans 3y ago
      I'm not sure which is more practical. Diverting enough material to replicate earth's natural magnetic core system on mars into the planet, or building an artificial system. The knowledge gained from attempting either is likely valuable.

morkalork 3y ago

That's a pretty good comparison. We go to space but it's a fleeting excursion so far and we haven't yet evolved the necessary abilities to make it permanent

Charon77 3y ago
If a planet in the nearest star harbors life form that launched a rocket, would we know?
- cryptoz 3y ago
  No, we wouldn't know today. But this is knowable in about 50 years or so, if we send probes to ~550AU and use the Sun as a gravitational lens; we will then be able to get high-res (1km resolution?) photos/videos of nearby extrasolar planets themselves. This may be enough to find a spacefaring civilization. (sure, rockets aren't 1km big, but they do leave big traces. maybe we could see that)
  - Qem 3y ago
    > if we send probes to ~550AU and use the Sun as a gravitational lens; we will then be able to get high-res (1km resolution?) photos/videos of nearby extrasolar planets themselves. It doesn't scale well. The probe would be able to observe a carefully chosen extrasolar planetary system in the opposite direction in relation to the sun. If you want to observe a second system, it's necessary to launch a second probe 550 AU in another direction. You can't change targets just by rotating the probe, given its lens is the sun.
    - cryptoz 3y ago
      Oh yeah, I'm aware that you'll need multiple probes - but I imagine we could send 50 or 100 of these things starting in like 20-30 years once some of the required engineering on propulsion systems etc is done. Assuming we have the will and money to send 1, I think we'd have the will and money to send dozens.
  - defrost 3y ago
    As Qem mentioned, and as laid out on page 7 of the source paper: A significant difference of the solar gravitational lens from a conventional telescope is that the gravitational lens telescope is not in any practical sense pointable. For the telescope at a distance F from the sun to be re-aimed to image a new target 1° away, it would have to move a distance of (π/180°)F, which is 10 astronomical units at the minimum focal distance-- a lateral distance equivalent to the distance from Earth to Saturn. This means that, in practice, such a telescope is not able to be repointed. Thus, a telescope at the gravitational focus is necessarily going to be a singlepurpose telescope, with the target of observation selected before the mission is launched. A gravitational focus mission can’t be used as a telescope to search for a target: such a mission must be with the objective to observe a target whose position is already known. Mission to the Gravitational Focus of the Sun: A Critical Analysis Geoffrey A. Landis, NASA John Glenn Research Center https://arxiv.org/ftp/arxiv/papers/1604/1604.06351.pdf https://arxiv.org/ftp/arxiv/papers/1604/1604.06351.pdf
  - p1mrx 3y ago
    That seems like a good match for this nuclear sail concept: https://www.nasa.gov/general/thin-film-isotope-nuclear-engine-rocket/ https://www.nasa.gov/general/thin-film-isotope-nuclear-engin... > The basic concept is to manufacture thin sheets of a radioactive isotope and directly use the momentum of its decay products to generate thrust. Actually it's mentioned at the end of the article: > Novel ability to reach deep space (> 150 AU) very quickly and then continue aggressive maneuvers (> 100 km/sec) for dim object search/rendezvous and/or retargeting telescopes at the solar gravitational focus over a period of years.

zarzavat 3y ago

That’s just because our neighbourhood is so boring in comparison to Earth. Imagine that by some chance Mars was another Earth with a breathable atmosphere. NASA would have been given a trillion dollar budget and we would have been there in the 80s. Instead it’s a dead red rock so NASA gets a small budget and the US spends its money on blowing people up instead. We have the technology to be a spacefaring civilisation but we won’t care until Earth becomes a worse place to be than the rest of the solar system, which is probably never given how bad the other bodies in the solar system are. Most likely we develop Von Neumann probes before we ever get bored of Earth.

XorNot 3y ago
I do keep hoping we get lucky in my lifetime and a massive, water bearing comet with slam into Mars and jumpstart the terraforming. Watching a planet which could retain water go from "nothing to oceans" would be amazing.
- lostemptations5 3y ago
  Evidence suggests Mars had oceans before and they just evaporated due to the thin atmosphere and non-existant magnetic field no? I'm not sure how that would get solved without some active technological solution by humans let's say.
  - XorNot 3y ago
    Over a timespan of hundreds of thousands of years. Which is short in geological terms, but an eternity in technological ones. We would have plenty of time to solve that problem.
  - mjevans 3y ago
    I'm not sure which is more practical. Diverting enough material to replicate earth's natural magnetic core system on mars into the planet, or building an artificial system. The knowledge gained from attempting either is likely valuable.