11 ms·

Thruster for Mars mission breaks records

141 points by skolos 9y ago

samstave 9y ago
[tinfoil] So at what point is musk and all these others going to have to be called into to a room to have a sit-down for the break-away civilization leaders to tell them what they can and can’t do? [/tinfoil]
ctdonath 9y ago
What's the mass consumption/ejection rate for this thing? What's the power consumption rate? Wondering if a non-solar power source (batteries, nuclear, etc) could cannibalize its waste fuel as ejection material.
sp332 9y ago
102kW? How do they plan to provide power for that on a spaceship?
- Gravityloss 9y ago
  Solar cells. Electric propulsion is potentially good for a cargo carrier, where you don't care so much about the extra acceleration time.
- Symmetry 9y ago
  For Mars probably solar. The ISS's panels provide that much. Any time you're looking at electric propulsion your power plant is going to be a big fraction of your vehicle weight.
  - sp332 9y ago
    The current prototype weighs 500 pounds (226 kg) so it could just accelerate itself at 1/400 g. After 100 hours it could be moving at 8,500 m/s but that's not including cargo or solar panels.
    - Someone 9y ago
      The Voyagers do around twice that at the moment. So, (very much ballpark, and ignoring all additional weight for fuel, etc.), would that mean this could reach three times their speed in a month, and, after that, catch up with one of them in 15 years or so? If so, is it feasible to build one with enough fuel to accelerate for a year or so? If so, where’s the billionaire willing to spend a few quid on a machine that goes out to photograph one of the Voyagers from close up while it zooms by, or even bring one of them back to earth before the century is over?
      - Symmetry 9y ago
        So, getting up to 25.5 km/s with a rocket with an exhaust velocity of 30 km/s means you need the wet weight to be 2.33 times the dry weight. Last I checked [1] you can get 77 W/kg with photovoltaics so you need you'll need 1402 kg of those in addition to the 226 kg of engine for a total of 1626 kg. Round that up to 2200 kg for structure and tankage and so on for a total we mass of 5126 kg where 2926 kg of that is fuel. You're using that at 5.4/30000=.00018 kg/s for a total of 16255555 seconds of acceleration or about six months. So six months instead of one but basically yes. [1]http://hopefullyintersting.blogspot.com/2015/03/rockets-electric-propulsion.html http://hopefullyintersting.blogspot.com/2015/03/rockets-elec... EDIT: Of course, as it accelerates it'll get further away from the sun leading to less power from the solar panels and a slower acceleration.
        sp332 9y ago
        Xenon is apparently pretty expensive, like $1,200/kg. Just running it for 100 hours at 0.00018 kg/s will cost $76,800 for the propellant. Plus 10,200 kWh of electricity!
        jandrese 9y ago
        For a deep space probe that fuel cost is not a showstopper. That's well down in the weeds compared to the cost of launching it to orbit and manning the tracking stations and buying airtime on the Deep Space Network.
Symmetry 9y ago
Doing the math on this 5.4 netwons in 108 kilowatts would give you a maximum exhaust velocity of 38 km/s which is in line with what you expect from a Hall effect thruster. You can get much higher exhaust velocities (and thus more fuel efficient engines) from gridded ion engine but that requires more power for a given thrust and the wear on the grid is a concern. I'm not really sure why it's important that we have big hall thrusters, though? My impression was that you could just keep adding more of these to a spacecraft if you needed to.
- sp332 9y ago
  It seems like the bigger ones are more efficient. Looking at the design I think they nested several hall effect thrusters which could improve focus or something. Edit: http://pepl.engin.umich.edu/projects/NCHETs.html http://pepl.engin.umich.edu/projects/NCHETs.html
- deleted 9y ago
  [deleted]
- matthew349hall 9y ago
  Why not have a nuclear battery/generator powering an array of ion thrusters?
- btilly 9y ago
  This is a tradeoff that I don't think is widely enough understood. The faster the rocket's exhaust goes the less fuel and more energy you need to reach a given speed. This only makes sense if you have access to a lot of energy, and are concerned with conserving fuel.
nickik 9y ago
The hole of Space exploration is really hindered by the approach to nuclear power. Many missions that could fly with nuclear batteries don't use them. Rosetta would have been a far better mission with one. On a larger scale we should have nuclear reactors in space. If we ever want a mars colony, nuclear is way, way better then solar. Elon Musk is gone try with solar but he really doesn't have any other options. NASA is the one place there can actually be progress on this stuff, no private company can reasonable attempted this stuff because of regulation. We need more nuclear batteries, we need small reactors for space and we need nuclear thermal rockets engines.
- Gravityloss 9y ago
  It's not so easy to make space nuclear power light and reliable. Most likely a nuclear powered spacecraft with electric thrusters would be a dog. Nuclear thermal rockets aren't that great either, the temperature and thus the specific impulse is not very high, and they have high dry mass and would be really expensive to develop and hard to make reliable. In space you have 1.3 kW per square meter sun power constantly without the atmosphere or clouds in the way, and solar cells improve constantly.
  - chesimov 9y ago
    I think it's more like ~0.6kW/m^2 out at Mars
  - kakali 9y ago
    I think your 1.3 kW number assumes being near Earth.
  - camiller 9y ago
    "...1.3 kW per square meter sun power constantly..." at Earth's distance from the sun. At Mars it is .715 kW. Inverse square law and all that.
    - sdenton4 9y ago
      New plan! Colonize Venus! (What's all this about cloud cover?)
dang 9y ago
Url changed from https://newatlas.com/x3-hall-thruster-test-record-nasa/51869/ https://newatlas.com/x3-hall-thruster-test-record-nasa/51869..., which points to this.
jtchang 9y ago
Weren't we still unsure how the thruster actually worked? As in where the thrust was coming from?
- Elv13 9y ago
  No, that's the EM drive. This engine is less or more a particle accelerator shooting high velocity noble gas. It's like a rocket (less or more), but instead of using a lot of slow matter, it use a little, but very fast, matter. It still requires a supply of matter to trow from the back of the spacecraft, it just uses it in a way to minimize the amount required (by trading it by silly amount of power). It's based on the classic `F=m*a` Newtonian second law. But uses high `a` instead of high `m`. The Hall and Ion engines just replace chemical energy with electricity. Edit: Added the `F=ma` part. Edit2: Added that it still requires matter.
  - samstave 9y ago
    But you still need to give it a supply of noble gas, correct? So how many AU per unit of noble gas do you reach at terminal velocity of the thing? Also what are the manufacturing limitations for noble supply - given all the talk about us running out of helium. Aside: it would be ironic if they had helium balloons at the launch party of some such rocket... Finally, what is the state of the noble gas when consumed by this engine in a full vacuum of space? Is it destroyed into a state that is unrecoverable?
    - JumpCrisscross 9y ago
      > terminal velocity of the thing? What?
      - hyperbovine 9y ago
        c
        camiller 9y ago
je42 9y ago
how does this compare to Space-X Raptor engines ?
- lutorm 9y ago
  Raptor is a conventional chemical rocket engine. The thrust is much higher (of order 1 million N vs 5N) but the specific impulse is much worse so your ability to reach speeds is limited by the amount of propellant you need to carry.
- foxyv 9y ago
  Typically hall effect thrusters have an ISP of 1600 while Raptors have an ISP of 375 in a vacuum. In a cost benefit analysis this is what makes electric propulsion sensible for long term missions. Otherwise their low thrust and heavy weight (Thruster and electrical generator) would make them unappealing.
zlynx 9y ago
One of the best things about these thrusters is how they look exactly like a science fiction space thruster should. This would not look out of place on a Star Destroyer or a Federation Constitution class cruiser.
the8472 9y ago
Isn't corrosion an issue with hall thrusters, especially at high power and long-duration firings? At least that was one of the selling points of VASIMR over ion thrusters.

141 points by skolos 9y ago

[tinfoil] So at what point is musk and all these others going to have to be called into to a room to have a sit-down for the break-away civilization leaders to tell them what they can and can’t do? [/tinfoil]

ctdonath 9y ago

What's the mass consumption/ejection rate for this thing? What's the power consumption rate? Wondering if a non-solar power source (batteries, nuclear, etc) could cannibalize its waste fuel as ejection material.

sp332 9y ago

102kW? How do they plan to provide power for that on a spaceship?

Gravityloss 9y ago
Solar cells. Electric propulsion is potentially good for a cargo carrier, where you don't care so much about the extra acceleration time.
Symmetry 9y ago
For Mars probably solar. The ISS's panels provide that much. Any time you're looking at electric propulsion your power plant is going to be a big fraction of your vehicle weight.
- sp332 9y ago
  The current prototype weighs 500 pounds (226 kg) so it could just accelerate itself at 1/400 g. After 100 hours it could be moving at 8,500 m/s but that's not including cargo or solar panels.
  - Someone 9y ago
    The Voyagers do around twice that at the moment. So, (very much ballpark, and ignoring all additional weight for fuel, etc.), would that mean this could reach three times their speed in a month, and, after that, catch up with one of them in 15 years or so? If so, is it feasible to build one with enough fuel to accelerate for a year or so? If so, where’s the billionaire willing to spend a few quid on a machine that goes out to photograph one of the Voyagers from close up while it zooms by, or even bring one of them back to earth before the century is over?
    - Symmetry 9y ago
      So, getting up to 25.5 km/s with a rocket with an exhaust velocity of 30 km/s means you need the wet weight to be 2.33 times the dry weight. Last I checked [1] you can get 77 W/kg with photovoltaics so you need you'll need 1402 kg of those in addition to the 226 kg of engine for a total of 1626 kg. Round that up to 2200 kg for structure and tankage and so on for a total we mass of 5126 kg where 2926 kg of that is fuel. You're using that at 5.4/30000=.00018 kg/s for a total of 16255555 seconds of acceleration or about six months. So six months instead of one but basically yes. [1]http://hopefullyintersting.blogspot.com/2015/03/rockets-electric-propulsion.html http://hopefullyintersting.blogspot.com/2015/03/rockets-elec... EDIT: Of course, as it accelerates it'll get further away from the sun leading to less power from the solar panels and a slower acceleration.
      - sp332 9y ago
        Xenon is apparently pretty expensive, like $1,200/kg. Just running it for 100 hours at 0.00018 kg/s will cost $76,800 for the propellant. Plus 10,200 kWh of electricity!
        jandrese 9y ago
        For a deep space probe that fuel cost is not a showstopper. That's well down in the weeds compared to the cost of launching it to orbit and manning the tracking stations and buying airtime on the Deep Space Network.

Symmetry 9y ago

Doing the math on this 5.4 netwons in 108 kilowatts would give you a maximum exhaust velocity of 38 km/s which is in line with what you expect from a Hall effect thruster. You can get much higher exhaust velocities (and thus more fuel efficient engines) from gridded ion engine but that requires more power for a given thrust and the wear on the grid is a concern. I'm not really sure why it's important that we have big hall thrusters, though? My impression was that you could just keep adding more of these to a spacecraft if you needed to.

sp332 9y ago
It seems like the bigger ones are more efficient. Looking at the design I think they nested several hall effect thrusters which could improve focus or something. Edit: http://pepl.engin.umich.edu/projects/NCHETs.html http://pepl.engin.umich.edu/projects/NCHETs.html
deleted 9y ago
[deleted]
matthew349hall 9y ago
Why not have a nuclear battery/generator powering an array of ion thrusters?
btilly 9y ago
This is a tradeoff that I don't think is widely enough understood. The faster the rocket's exhaust goes the less fuel and more energy you need to reach a given speed. This only makes sense if you have access to a lot of energy, and are concerned with conserving fuel.

nickik 9y ago

The hole of Space exploration is really hindered by the approach to nuclear power. Many missions that could fly with nuclear batteries don't use them. Rosetta would have been a far better mission with one. On a larger scale we should have nuclear reactors in space. If we ever want a mars colony, nuclear is way, way better then solar. Elon Musk is gone try with solar but he really doesn't have any other options. NASA is the one place there can actually be progress on this stuff, no private company can reasonable attempted this stuff because of regulation. We need more nuclear batteries, we need small reactors for space and we need nuclear thermal rockets engines.

Gravityloss 9y ago
It's not so easy to make space nuclear power light and reliable. Most likely a nuclear powered spacecraft with electric thrusters would be a dog. Nuclear thermal rockets aren't that great either, the temperature and thus the specific impulse is not very high, and they have high dry mass and would be really expensive to develop and hard to make reliable. In space you have 1.3 kW per square meter sun power constantly without the atmosphere or clouds in the way, and solar cells improve constantly.
- chesimov 9y ago
  I think it's more like ~0.6kW/m^2 out at Mars
- kakali 9y ago
  I think your 1.3 kW number assumes being near Earth.
- camiller 9y ago
  "...1.3 kW per square meter sun power constantly..." at Earth's distance from the sun. At Mars it is .715 kW. Inverse square law and all that.
  - sdenton4 9y ago
    New plan! Colonize Venus! (What's all this about cloud cover?)

dang 9y ago

Url changed from https://newatlas.com/x3-hall-thruster-test-record-nasa/51869/ https://newatlas.com/x3-hall-thruster-test-record-nasa/51869..., which points to this.

jtchang 9y ago

Weren't we still unsure how the thruster actually worked? As in where the thrust was coming from?

Elv13 9y ago
No, that's the EM drive. This engine is less or more a particle accelerator shooting high velocity noble gas. It's like a rocket (less or more), but instead of using a lot of slow matter, it use a little, but very fast, matter. It still requires a supply of matter to trow from the back of the spacecraft, it just uses it in a way to minimize the amount required (by trading it by silly amount of power). It's based on the classic `F=m*a` Newtonian second law. But uses high `a` instead of high `m`. The Hall and Ion engines just replace chemical energy with electricity. Edit: Added the `F=ma` part. Edit2: Added that it still requires matter.
- samstave 9y ago
  But you still need to give it a supply of noble gas, correct? So how many AU per unit of noble gas do you reach at terminal velocity of the thing? Also what are the manufacturing limitations for noble supply - given all the talk about us running out of helium. Aside: it would be ironic if they had helium balloons at the launch party of some such rocket... Finally, what is the state of the noble gas when consumed by this engine in a full vacuum of space? Is it destroyed into a state that is unrecoverable?
  - JumpCrisscross 9y ago
    > terminal velocity of the thing? What?
    - hyperbovine 9y ago
      c
      - camiller 9y ago

je42 9y ago

how does this compare to Space-X Raptor engines ?

lutorm 9y ago
Raptor is a conventional chemical rocket engine. The thrust is much higher (of order 1 million N vs 5N) but the specific impulse is much worse so your ability to reach speeds is limited by the amount of propellant you need to carry.
foxyv 9y ago
Typically hall effect thrusters have an ISP of 1600 while Raptors have an ISP of 375 in a vacuum. In a cost benefit analysis this is what makes electric propulsion sensible for long term missions. Otherwise their low thrust and heavy weight (Thruster and electrical generator) would make them unappealing.

zlynx 9y ago

One of the best things about these thrusters is how they look exactly like a science fiction space thruster should. This would not look out of place on a Star Destroyer or a Federation Constitution class cruiser.

the8472 9y ago

Isn't corrosion an issue with hall thrusters, especially at high power and long-duration firings? At least that was one of the selling points of VASIMR over ion thrusters.