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No it didn't. Transmitting power via microwave radio signal through a vacuum is no new thing. That's all they did here: transmit power a meter or two across the

No it didn't. Transmitting power via microwave radio signal through a vacuum is no new thing. That's all they did here: transmit power a meter or two across the inside of the spacecraft while it was in space. They did not even attempt to do transmission of power to ground for obvious reasons. At 9.84 GHz their ~meter scale aperture from 400km LEO orbit to the biggest NASA dish in existence (that could track LEO) would have a path loss of 76 dB. That means something like (being generous) 0.0000000001% of the power would make it. Plenty for carrying information but useless for beaming power. Space solar power requires coherent emitting apertures on the order of a handful of kilometers to be feasible (from LEO). We can't build kilometer scale anything in LEO. End of story. Once that changes we can think about space solar power.

jahnu 3y ago
> No it didn't. I think you are reading something in the headline that isn't there. They ended their first space based mission which was to test various things. It wasn't to beam power back to Earth. The details in the article are actually interesting.
- superkuh 3y ago
  I read the article. It's glaringly obvious that the goal is space solar power to earth. >"Solar power beamed from space at commercial rates, lighting the globe, is still a future prospect. But this critical mission demonstrated that it should be an achievable future," says Caltech President Thomas F. Rosenbaum, the Sonja and William Davidow Presidential Chair and professor of physics. This mission did nothing to show that was achievable. The hard part isn't the vacuum. It's the distance which requires, because of physics, a large coherent emitting aperture. And the larger your aperture the harder it is to point. If they really wanted to make progress towards this they'd be building a km-scale coherent phased array for power transmission here on earth. The EISCAT scattering radars in the artic circle are much closer to proving feasibility for space based solar power than this is.
  - dekhn 3y ago
    You're being pedantic, and incorrectly pedantic. Complaining about a scientist saying "it's a future prosect... that should be an achievable future" is just silly. Look, I get it. I see a PR and I get angry at the implications. But it's just not worth overinterpreting this PR as justifying future research into beamed power delivery. My guess would be this has space-based military applications they're not discussing but that's purely speculation based on what we believe the military space community is already exploring.
dekhn 3y ago
There's nothing in the press release to suggest that his specific mission was intended to demonstrate a working, economic delivery of power to earth. The article is clear about this, and the title is accurate. Whether it makes any sense to continue this line of research is an open question; they seem to be very far from having something that would produce useful power, with a long line of technical challenges facing them.
mattashii 3y ago
Many modern earth imaging satellites use something called "synthetic aperture radar" where the movement of the satellite is used to increase the aperture for the radar larger than the satellite's own dimensions. Could a similar mechanism be used as well for space to earth energy transfer, or is that unrealistic at the orbital speeds of LEO?
- superkuh 3y ago
  Synthetic apertures are not applicable to power transmission. That's just information processing. The velocity at which you're traveling doesn't matter. It can be done from plane. Or balloon. Or a walking human. You just have to transmit and receive from spots some distance apart multiple times (in a smaller timescale than your target is moving).
grecy 3y ago
In case you missed it, this is Hacker News. Where people post inspiring and interesting things we can learn from, we can aspire to and maybe even improve some things from time to time. There's no need for all the negativity every time someone tries something new. It serves no purpose.
- superkuh 3y ago
  https://www.caltech.edu/about/news/caltech-announces-breakthrough-100-million-gift-to-fund-space-based-solar-power-project https://www.caltech.edu/about/news/caltech-announces-breakth... The only reason Caltech is doing this is that a really rich person with delusions gave them 100 million dollars to research space based solar power. They know as well as anyone with a bit of RF experience that what they're doing isn't really increasing the TRL of space based solar power transmission. It's just humoring the donor for the money. The best that can be said is that it's the first flex pcb RF system in orbit. That's kind of cool but as a person looking to be inspired and improve things it seems like a significant waste of money. It's not like high power RF transmitters haven't been tested in vacuum in LEO before. There have been many, many radar satellites. They should've been spending they $100 million attempting to make coherent kilometer scale transmitting apertures on Earth and actually demo something that'd prove the feasibility of space based solar power transmission.
  - grecy 3y ago
    > They should've been spending they $100 million attempting to make... I'm not sure you understand how the world works. You don't get to decide how institutions spend money that is donated to them, and I really don't know why you think you do.
    - superkuh 3y ago
      If the donor really wanted to work towards space based power the experts could convince them the first step is achieving KM-scale coherent transmitting aperatures on Earth. If they just want the money and have no intention of fulfilling the goal, or if the dude is as you say... not open to input, then yeah, you end up with waste like here.
gene-h 3y ago
Caltech's approach[0] is to make their satellite with solar panels on one side and a transmit antenna on the other, so pretty much the whole area of solar panels serves as a giant phased array transmit aperture. They claim that this approach can be made very lightweight and might only mass 160 g/m^2. Kilometer space structures need not be very massive, as the loads they are subject to are quite small. More often achieving a certain stiffness, such that the structure doesn't wobble around too much when being repointed, drives design more than resisting structural loads. The main loading case they consider in [0] is solar radiation pressure. Making the entire structure coherent gets interesting as it's expected to flex a bit. However, they have demonstrated methods to correct for this flex[1]. One problem they have is that their satellite has to consist of a number of smaller spacecraft connected to each other in a grid because they can't launch the whole structure at the same time. One person involved with the project had concerns about how they would align each spacecraft to within subwavelength accuracy. [0]https://arxiv.org/ftp/arxiv/papers/2206/2206.08373.pdf https://arxiv.org/ftp/arxiv/papers/2206/2206.08373.pdf [1]https://www.nature.com/articles/s41528-022-00218-z https://www.nature.com/articles/s41528-022-00218-z

jahnu 3y ago

> No it didn't. I think you are reading something in the headline that isn't there. They ended their first space based mission which was to test various things. It wasn't to beam power back to Earth. The details in the article are actually interesting.

superkuh 3y ago
I read the article. It's glaringly obvious that the goal is space solar power to earth. >"Solar power beamed from space at commercial rates, lighting the globe, is still a future prospect. But this critical mission demonstrated that it should be an achievable future," says Caltech President Thomas F. Rosenbaum, the Sonja and William Davidow Presidential Chair and professor of physics. This mission did nothing to show that was achievable. The hard part isn't the vacuum. It's the distance which requires, because of physics, a large coherent emitting aperture. And the larger your aperture the harder it is to point. If they really wanted to make progress towards this they'd be building a km-scale coherent phased array for power transmission here on earth. The EISCAT scattering radars in the artic circle are much closer to proving feasibility for space based solar power than this is.
- dekhn 3y ago
  You're being pedantic, and incorrectly pedantic. Complaining about a scientist saying "it's a future prosect... that should be an achievable future" is just silly. Look, I get it. I see a PR and I get angry at the implications. But it's just not worth overinterpreting this PR as justifying future research into beamed power delivery. My guess would be this has space-based military applications they're not discussing but that's purely speculation based on what we believe the military space community is already exploring.

dekhn 3y ago

There's nothing in the press release to suggest that his specific mission was intended to demonstrate a working, economic delivery of power to earth. The article is clear about this, and the title is accurate. Whether it makes any sense to continue this line of research is an open question; they seem to be very far from having something that would produce useful power, with a long line of technical challenges facing them.

mattashii 3y ago

Many modern earth imaging satellites use something called "synthetic aperture radar" where the movement of the satellite is used to increase the aperture for the radar larger than the satellite's own dimensions. Could a similar mechanism be used as well for space to earth energy transfer, or is that unrealistic at the orbital speeds of LEO?

superkuh 3y ago
Synthetic apertures are not applicable to power transmission. That's just information processing. The velocity at which you're traveling doesn't matter. It can be done from plane. Or balloon. Or a walking human. You just have to transmit and receive from spots some distance apart multiple times (in a smaller timescale than your target is moving).

grecy 3y ago

In case you missed it, this is Hacker News. Where people post inspiring and interesting things we can learn from, we can aspire to and maybe even improve some things from time to time. There's no need for all the negativity every time someone tries something new. It serves no purpose.

superkuh 3y ago
https://www.caltech.edu/about/news/caltech-announces-breakthrough-100-million-gift-to-fund-space-based-solar-power-project https://www.caltech.edu/about/news/caltech-announces-breakth... The only reason Caltech is doing this is that a really rich person with delusions gave them 100 million dollars to research space based solar power. They know as well as anyone with a bit of RF experience that what they're doing isn't really increasing the TRL of space based solar power transmission. It's just humoring the donor for the money. The best that can be said is that it's the first flex pcb RF system in orbit. That's kind of cool but as a person looking to be inspired and improve things it seems like a significant waste of money. It's not like high power RF transmitters haven't been tested in vacuum in LEO before. There have been many, many radar satellites. They should've been spending they $100 million attempting to make coherent kilometer scale transmitting apertures on Earth and actually demo something that'd prove the feasibility of space based solar power transmission.
- grecy 3y ago
  > They should've been spending they $100 million attempting to make... I'm not sure you understand how the world works. You don't get to decide how institutions spend money that is donated to them, and I really don't know why you think you do.
  - superkuh 3y ago
    If the donor really wanted to work towards space based power the experts could convince them the first step is achieving KM-scale coherent transmitting aperatures on Earth. If they just want the money and have no intention of fulfilling the goal, or if the dude is as you say... not open to input, then yeah, you end up with waste like here.

gene-h 3y ago

Caltech's approach[0] is to make their satellite with solar panels on one side and a transmit antenna on the other, so pretty much the whole area of solar panels serves as a giant phased array transmit aperture. They claim that this approach can be made very lightweight and might only mass 160 g/m^2. Kilometer space structures need not be very massive, as the loads they are subject to are quite small. More often achieving a certain stiffness, such that the structure doesn't wobble around too much when being repointed, drives design more than resisting structural loads. The main loading case they consider in [0] is solar radiation pressure. Making the entire structure coherent gets interesting as it's expected to flex a bit. However, they have demonstrated methods to correct for this flex[1]. One problem they have is that their satellite has to consist of a number of smaller spacecraft connected to each other in a grid because they can't launch the whole structure at the same time. One person involved with the project had concerns about how they would align each spacecraft to within subwavelength accuracy. [0]https://arxiv.org/ftp/arxiv/papers/2206/2206.08373.pdf https://arxiv.org/ftp/arxiv/papers/2206/2206.08373.pdf [1]https://www.nature.com/articles/s41528-022-00218-z https://www.nature.com/articles/s41528-022-00218-z