Jan 05, 2017 02:45 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Dec 18, 2016 16:14 michael.million@sky.com Posted on: Centauri Dreams
"If I get this right, isn't the magnitude of the power requirement about the same as Dr Gerald P Jackson envisages for his antimatter factory (~40GW)? http://www.antimatterdrive.org/index.htm Maybe there is more than one use for a facility like this."
Yes it could aid an antimatter factory, it could also be used for asteroid defence, if we accelerate a sail say with a deuterium package at high enough velocity it will undergo fusion and release a large amount of energy on impact. It could also much later be used to send out materials that could be used in a pellet runway system to supply a much larger probe/ship with fuel without it having to carry it."

Answer:
Thanks for your help. We agree that after these facilities are developed there will be several spin offs and other ancillary activities associated with this effort.

- Pete Klupar, Breakthrough Starshot

Jun 06, 2017 03:22 Robert Clark Posted on: Breakthrough Initiatives

NASA just announced a solar probe to travel quite close to the Sun, about 3.7 million miles from the solar surface:

Nasa’s hotly anticipated solar mission renamed to honour astrophysicist Eugene Parker.
Renamed the Parker Solar Probe to honour solar astrophysicist who predicted high speed solar wind, the spacecraft will attempt to get close to sun’s surface.
Wednesday 31 May 2017 07.08 EDT
https://www.theguardian.com/science/2017/may/31/nasa-to-announce-details-of-hotly-anticipated-mission-to-the-sun-solar-probe-plus

Spacecraft able to get this close to the Sun could potentially allow beamed interstellar propulsion. For a spacecraft of any size, you would need huge amounts of beamed power. Where to get it? If you make the beam be solar-powered then can just use space-borne mirrors to focus the Suns rays. But the mirror(s) would have to be impractically large if they were in Earth orbit.
But what if we placed them close to the Sun? At the distance quoted of 3.7 million miles away from the Sun, a mirror 1 km on a side could collect a terawatt worth of power.

Note this means this could also provide space solar power to Earth. Two of these 1 km wide mirrors could supply the electricity usage of the entire world. The possibility of providing total worldwide electrical power might allow funding for the proposal beyond that just for space exploration purposes.

Bob Clark

Jun 15, 2017 14:47 Robert Clark Posted on: Centauri Dreams

At the distance of the Parker probe, a 1 km sq. mirror could collect a terawatt of power for beamed propulsion or space solar power beamed to Earth.

But could we put the mirror actually on the surface of the Sun? The Sun puts out 3.86X10^26 watts of power, http://m.wolframalpha.com/input/?i=solar+luminosity&x=0&y=0.

Given its 700,000 km radius, this amounts to over 60 terawatts per sq. km. This is 3 times the total energy usage of humans on Earth from all sources.

Could we have a station on the Sun's surface that would persist long term? The Sun's surface is at about 5,500 C. The highest temperature ceramic we have is at about 4,000 C:

Rediscovered ceramic Hafnium Carbide can withstand temperatures three times hotter than lava at 4050 celsius and could help enable hypersonic planes.
brian wang | September 17, 2014
https://www.nextbigfuture.com/2014/09/rediscovered-ceramic-hafnium-carbine.html

However, there are cases such as with rocket engine combustion chambers where the operating temperature is well above the melting point of the material composing the engine. The reason this is possible is that in order for a material to undergo a phase change from solid to liquid not only does it have to be at the melting point but a sufficient quantity of heat known as the heat of fusion has to be supplied to it.

So with high performance rocket engines such as the SSME's a cooling techniques known as regenerative cooling is used that circulates cool fuel around the engine to draw off adequate heat to prevent melting from occurring.

However, with rocket engines this cooling fuel is burned or dispensed with after being used for the cooling. So this wouldn't work for a power station existing long term on the surface of the Sun. You would need something like a refrigeration system.

The Parker probe will use a refrigeration system to lower the temperature of the components of the spacecraft from 1,400 C to room temperature. This is about the same temperature drop as the temperature drop from the Sun's surface to the maximum temperature of our high temperature ceramics. So it should be possible to do this temperature drop on the surface of the Sun using our highest temperature ceramics.

Still, we might not want the extra difficulty of landing on the Sun. If we make the distance to the Sun of our beaming station about 1/3rd that of the Parker probe we would be at 10 terawatts per sq. km. Two of these would provide the entire energy requirements for the entire human population, and the surrounding temperatures wouldn't be so extreme.

Bob Clark

Jul 15, 2017 03:42 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
Jun 06, 2017 03:22 Robert Clark Posted on: Breakthrough Initiatives

Answer:
This is a cool idea but would be very difficult to implement. Keep in mind that the mirrors you’re talking about would be moving on heliocentric orbits and would not always be in view of the Earth.

- Zac Manchester, Breakthrough Starshot

Jul 15, 2017 03:43 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
Jun 15, 2017 14:47 Robert Clark Posted on: Centauri Dreams

Answer:
An interesting idea, but I think there are a few important problems with it. In addition to the obvious thermal issues, the mirrors would be moving on their own heliocentric orbits, and not always able to point at the Earth.

- Zac Manchester, Breakthrough Starshot

May 26, 2020 19:04 decaf2023@gmail.com Posted on: Breakthrough Initiatives

Instead of landing on the surface of the Sun with a probe to beam power, why not put multiple probes in Heliostationary orbit? It would solve many of the thermal issues, as well as costing far less Delta-V in order to pull off.

Jun 25, 2020 15:53 Breakthrough Initiatives Posted on: Breakthrough Initiatives

Dear decaf2023,

Thanks for your input. I think you are correct that it would be far cheaper to build a system in heliocentric orbit (also called circumsolar orbit) than on the surface of the sun. Our current plan is to place the beamer on the surface of the earth. At current launch costs, this is the only feasible place to build a system that will be highly complex and have a map many thousands of tons.

Keep asking questions – it is especially important that we get your help to solve these problems.

Pete Klupar
Director of Engineering
Breakthrough Initiatives

May 26, 2021 01:16 jokocraft@yahoo.com Posted on: Breakthrough Initiatives

What if a miniature version of such laser array were to be built on a ship?

American air-craft carriers often have more than 10,000 square meters of surface area. They also have nuclear reactors capable of producing close to ~1 GW. This is about 1/100th scale model.

The US-Navy might provide funding and support for such mobile laser array as it may have anti-missile capabilities. A primary use of such floating laser would likely be to remove orbital space debris (NASA funding?). The mobility factor will allow it to target a greater variety of space junk.

Perhaps this array might be useful in sending lower-speed satellites to destinations within our solar system? Mobility of the array will allow it to be positioned in the best spot for any destination. This system be up-scaled by simply adding more of these array ships. Old container ships are less expensive and have great surface area. If power (generation and storage) is accounted for, it may be economically feasible to use them. Construction of these arrays will take place in port cities which have great infrastructure. Meanwhile, remote high-altitude areas can be difficult to access.

In the near future, there might be numerous decommissioned aircraft carriers. Could be an opportunity to learn and improve the needed technologies.