News for hackers. Stuff that matters.
Re:So, you want to build a CubeSat? by asdfman123 on Tuesday July 30, 2019 @01:06PM (#20566832)
Now I want to build a CubeSat that will point a laser pointer at different population centers as it passes around the earth. E.g. this pass of North America you choose LA, then NYC, then Houston, then Chicago... so you can see it streak by in the sky.

My rough estimation is you could create a spot 2 miles across with a standard laser pointer at 400 miles high. Maybe you could use a different kind that would have a little more spread. And you'd have even more if you weren't beaming directly downwards -- maybe you could point it at 45 degrees or more with a powerful laser and get nice coverage.

Re:So, you want to build a CubeSat? by modeless on Tuesday July 30, 2019 @01:28PM (#20567056)
You don't need a laser pointer. All you need to do is reflect sunlight. There was a recent attempt to deploy a cubesat that would become the brightest object in the night sky (besides the Moon), simply by deploying some white fabric. Unfortunately, or fortunately depending on your opinion (I lean toward the latter), it failed to fully deploy. http://spaceflight101.com/soyuz-kanopus-v-ik/mayak-lighthous...

Many satellites are visible to the naked eye; some even brighter than the stars. If you want to see them, heavens-above.org is a great place to find out when to look. https://heavens-above.com/PassSummary.aspx?satid=42830

Re:So, you want to build a CubeSat? by vkou on Tuesday July 30, 2019 @01:54PM (#20567366)
> Many satellites are visible to the naked eye; some even brighter than the stars.

And if you want to see an absolute cornucopia of satellites, grab a pair of binoculars, and look straight up, an hour or two after sunset.

You'll see faint little lights, crossing your field of vision, to and fro, on a very regular basis.

Re:So, you want to build a CubeSat? by massimo-nazaria on Wednesday July 31, 2019 @01:10PM (#20576190)
> Many satellites are visible to the naked eye; some even brighter than the stars. If you want to see them, heavens-above.org is a great place to find out when to look. https://heavens-above.com/PassSummary.aspx?satid=42830

Interesting link. Another interesting one is https://spotthestation.nasa.gov about the ISS, which is probably the most visible to the naked eye.

Re:So, you want to build a CubeSat? by xhgdvjky on Tuesday July 30, 2019 @01:20PM (#20566967)
cool idea for ten minutes but this is exactly the kind of pollution I don't want from cheaper satellites
Re:So, you want to build a CubeSat? by asdfman123 on Tuesday July 30, 2019 @01:27PM (#20567042)
I guess this is the space equivalent of when Clark Griswold's redneck cousin Eddie comes into town.

Move over, high falutin' space types! I want a laser pointer pointing at my house every night!

Re:So, you want to build a CubeSat? by snickmy on Tuesday July 30, 2019 @01:47PM (#20567291)
For a while I thought you would need too much energy, then I realized I don't know well enough the physics of how a laser works.

[Warning, very stupid idea ahead]: Since I don't know well enough the topic, why wouldn't be possible to use a satellite to collect solar energy (because outside the atmosphere you can collect ~40% more (edited) the solar energy due to lack of atmospheric filtering effect),and then transmit that energy back to earth via some sort of wireless energy distribution mechanism (laser?). I guess a YoYo satellite with real tens of KM of wire to earth has a lot of reasons for not be feasible.

Re:So, you want to build a CubeSat? by ohazi on Tuesday July 30, 2019 @01:55PM (#20567371)
It's not 40x more, it's barely 40% more. [1]

> Average annual solar radiation arriving at the top of the Earth's atmosphere is roughly 1361 W/m^2. The Sun's rays are attenuated as they pass through the atmosphere, leaving maximum normal surface irradiance at approximately 1000 W /m^2 at sea level on a clear day.

There are practical challenges, but otherwise, yes, it should work.

[1] https://en.wikipedia.org/wiki/Solar_irradiance#Irradiance_on...

Re:So, you want to build a CubeSat? by snickmy on Tuesday July 30, 2019 @02:19PM (#20567621)
Thank you for the pointer! I've updated the original comment, and my knowledge base too :)
Re:So, you want to build a CubeSat? by asdfman123 on Tuesday July 30, 2019 @01:53PM (#20567350)
It's actually not a terrible idea and it's been considered in depth before: https://en.wikipedia.org/wiki/Space-based_solar_power.

Like so many things it's got a few unsolved technical difficulties thought that make it not-quite feasible.

Re:So, you want to build a CubeSat? by ChuckMcM on Tuesday July 30, 2019 @02:49PM (#20567929)
Search "Solar power satellites". Lots of research, some unsolved problems, downlink is typically microwaves to a rectenna.
Re:So, you want to build a CubeSat? by erklik on Wednesday July 31, 2019 @02:34AM (#20572142)
I think its not that crazy an idea. The biggest issue ( based on my very limited knowledge reading online articles ), is that the transmission without a physical medium leaves a lot to be desired. Secondly, waste heat disposal is enough of a problem in space, but when your craft is designed to accept as much radiation as possible, it becomes even more so.

I do think that its certainly going to be one of the ways humanity powers themselves going into the future. As our power needs increase, we will inevitably look to more efficently use the power eminating from our star and one of the first steps in doing that is by harnessing it without the atmospheric effects.

Re:So, you want to build a CubeSat? by wickedlasers on Thursday August 01, 2019 @04:42AM (#20582143)
Maybe check out the lasercube for a laser you can program https://wickedlasers.com/cube