4 ms·

If aluminum is the issue, could steel and plastics be a solution? Especially with Starship coming online, weight should be less of an issue.

by golol 2y ago

justin66 2y ago
Anything’s possible but the mass of the satellite won’t cease to be something they need to optimize, even with a heavier booster. Those little satellites use thrusters themselves when they’re in orbit.
- ginko 2y ago
  There's also magnesium alloys, but if MgO is any better in the stratosphere is anyone's guess
  - dylan604 2y ago
    There's a lot of really smart people that understand chemistry at a much better level than the typical reader on an internet forum. Do we really need to "guess"? Seems like we could study this to actually determine what would happen with controlled experiments. One might go so far as to call that the scientific method.
    - s1artibartfast 2y ago
      Nope, it is unknowable because ginko doesnt know /s
- kortilla 2y ago
  The thrusters are to offset atmospheric drag, which accumulates with surface area, not mass.
  - justin66 2y ago
    Weird half-true comment. Imaging satellites change their orbits, satellites operating in constellations station-keep, etc.
    - kortilla 2y ago
      Station keeping is for drag, which is the only thing the vast majority of satellites maneuver for.
      - justin66 2y ago
        There are some oddities here. The least interesting is that drag is not the only reason satellites station keep and I can't imagine why you'd say it is. The weirdest is that we're actually having an argument about whether satellite mass continues to matter once the satellite is in orbit. More interestingly, the majority (perhaps not yet "vast majority" [0]) of active satellites right now are Starlink satellites. Those things actually maneuver all the time in the interest of collision avoidance, and the rate at which they maneuver is predicted to increases as the number of satellites increase for obvious reasons. [1] [0] https://www.visualcapitalist.com/who-owns-the-most-satellites/ https://www.visualcapitalist.com/who-owns-the-most-satellite... [1] https://www.space.com/starlink-satellite-conjunction-increase-threatens-space-sustainability https://www.space.com/starlink-satellite-conjunction-increas...
  - roywiggins 2y ago
    More mass still means you get less velocity out of your fuel, even if the drag stays constant.
    - ordu 2y ago
      But you also lose less velocity with the same drag.
- DennisP 2y ago
  Since Starship itself is made of steel, it seems possible that the satellites could be as well. Assuming it's overall heavier, you have to carry more fuel, and then the rocket equation kicks in and you have to carry more fuel than that. That's all extra weight that makes your launch more expensive. But if your cost to launch is $30/lb instead of $1200/lb, you've got the budget for it.
  - dr_orpheus 2y ago
    But it's not just the cost of the launch, its also going to be the cost of the satellite itself. More mass means you need larger reaction wheels (or CMGs) to control the attitude of the spacecraft, larger reaction wheels means you need more power to control those reaction wheels, more power means you need more solar arrays/batteries, more solar arrays means more mass and moment of inertia...which means you need larger reaction wheels and on and on and on. Often people talk about the "tyranny of the rocket equation" but many other things on a satellite are the "tyranny of other non-linear systems" You can end up seeing that in companies like K2 Space. Their goal is to take advantage of cheaper launch costs with large, cheap satellites. But if you read in the article [0] they had to do things like develop new reaction wheels in house because "there was not a suitable supply chain for spacecraft bus like Mega Class". Starting from scratch on mechanisms like that for space is not super cheap. https://spacenews.com/k2-space-plans-first-launch-as-company-wins-customers-for-its-large-satellite-bus/ https://spacenews.com/k2-space-plans-first-launch-as-company...
    - DennisP 2y ago
      These are good points, but I still think it's technically feasible to make non-aluminum satellites, and reasonably economical even if it costs somewhat more. If the only alternatives are giving up on large satellite networks or destroying the ozone layer, then switching away from aluminum seems like the way to go. I'm not claiming steel is the best option though. Other metals, or even non-metal materials as mentioned in other comments might be better. I don't think needing new components is really a downside except in the very short term. With much cheaper launch at much higher volume, we're going to be doing a lot of that anyway. We're going to have all sorts of new applications that weren't economically feasible before.
HPsquared 2y ago
Or visiting satellites to be deorbited and encapsulating them inside a re-entry vehicle with refractory tiles.

If aluminum is the issue, could steel and plastics be a solution? Especially with Starship coming online, weight should be less of an issue.

by golol 2y ago

If aluminum is the issue, could steel and plastics be a solution? Especially with Starship coming online, weight should be less of an issue.

justin66 2y ago

Anything’s possible but the mass of the satellite won’t cease to be something they need to optimize, even with a heavier booster. Those little satellites use thrusters themselves when they’re in orbit.

ginko 2y ago
There's also magnesium alloys, but if MgO is any better in the stratosphere is anyone's guess
- dylan604 2y ago
  There's a lot of really smart people that understand chemistry at a much better level than the typical reader on an internet forum. Do we really need to "guess"? Seems like we could study this to actually determine what would happen with controlled experiments. One might go so far as to call that the scientific method.
  - s1artibartfast 2y ago
    Nope, it is unknowable because ginko doesnt know /s
kortilla 2y ago
The thrusters are to offset atmospheric drag, which accumulates with surface area, not mass.
- justin66 2y ago
  Weird half-true comment. Imaging satellites change their orbits, satellites operating in constellations station-keep, etc.
  - kortilla 2y ago
    Station keeping is for drag, which is the only thing the vast majority of satellites maneuver for.
    - justin66 2y ago
      There are some oddities here. The least interesting is that drag is not the only reason satellites station keep and I can't imagine why you'd say it is. The weirdest is that we're actually having an argument about whether satellite mass continues to matter once the satellite is in orbit. More interestingly, the majority (perhaps not yet "vast majority" [0]) of active satellites right now are Starlink satellites. Those things actually maneuver all the time in the interest of collision avoidance, and the rate at which they maneuver is predicted to increases as the number of satellites increase for obvious reasons. [1] [0] https://www.visualcapitalist.com/who-owns-the-most-satellites/ https://www.visualcapitalist.com/who-owns-the-most-satellite... [1] https://www.space.com/starlink-satellite-conjunction-increase-threatens-space-sustainability https://www.space.com/starlink-satellite-conjunction-increas...
- roywiggins 2y ago
  More mass still means you get less velocity out of your fuel, even if the drag stays constant.
  - ordu 2y ago
    But you also lose less velocity with the same drag.
DennisP 2y ago
Since Starship itself is made of steel, it seems possible that the satellites could be as well. Assuming it's overall heavier, you have to carry more fuel, and then the rocket equation kicks in and you have to carry more fuel than that. That's all extra weight that makes your launch more expensive. But if your cost to launch is $30/lb instead of $1200/lb, you've got the budget for it.
- dr_orpheus 2y ago
  But it's not just the cost of the launch, its also going to be the cost of the satellite itself. More mass means you need larger reaction wheels (or CMGs) to control the attitude of the spacecraft, larger reaction wheels means you need more power to control those reaction wheels, more power means you need more solar arrays/batteries, more solar arrays means more mass and moment of inertia...which means you need larger reaction wheels and on and on and on. Often people talk about the "tyranny of the rocket equation" but many other things on a satellite are the "tyranny of other non-linear systems" You can end up seeing that in companies like K2 Space. Their goal is to take advantage of cheaper launch costs with large, cheap satellites. But if you read in the article [0] they had to do things like develop new reaction wheels in house because "there was not a suitable supply chain for spacecraft bus like Mega Class". Starting from scratch on mechanisms like that for space is not super cheap. https://spacenews.com/k2-space-plans-first-launch-as-company-wins-customers-for-its-large-satellite-bus/ https://spacenews.com/k2-space-plans-first-launch-as-company...
  - DennisP 2y ago
    These are good points, but I still think it's technically feasible to make non-aluminum satellites, and reasonably economical even if it costs somewhat more. If the only alternatives are giving up on large satellite networks or destroying the ozone layer, then switching away from aluminum seems like the way to go. I'm not claiming steel is the best option though. Other metals, or even non-metal materials as mentioned in other comments might be better. I don't think needing new components is really a downside except in the very short term. With much cheaper launch at much higher volume, we're going to be doing a lot of that anyway. We're going to have all sorts of new applications that weren't economically feasible before.

HPsquared 2y ago

Or visiting satellites to be deorbited and encapsulating them inside a re-entry vehicle with refractory tiles.