First Image from Sony Star Sphere Satellite Released | Hacker News Reader

First Image from Sony Star Sphere Satellite Released

tlpnetwork.com

78 pointsBrajeshwar37 comments

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HNHTD, here's the archive.org link:

https://web.archive.org/web/20230227151050/https://tlpnetwor...

"HNHTD"?

HN hugged to death?

434F5252454354.

>offering an unprecedented opportunity for users to select one of 16 possible orbits, each of which can be completed in approximately 90 minutes.

Does the satellite actually change orbits for every user? That seems super expensive, propellant-wise. Or just 16 different tracks from the earth's precession?

Also, I'm not sure if this is actually the first satellite that let regular people take their own satellite pictures -I believe Ardusat aka Nanosatisfi aka Spire previously let people rent the cameras on their cubesats

Edit: actually I'm not sure if Ardusat ever actually let users use the camera feature

Most satellite imagery companies (Planet, Maxar, Satellogic etc.) allow users to pay for "tasked" imagery over an area within a given time window. This article doesn't explain why this Sony effort is the first of its kind in that regard.

> That seems super expensive, propellant-wise.

It would be ludicrously expensive. If "different orbits" means different orbital inclinations, you would be better off launching another satellite for each one. It's that expensive (there's at least one case of a satellite operator sending the satellite to the Moon and back, as it was cheaper).

If it meant different orbits as different altitudes, that would still be expensive if we wanted to allow anyone to request a different one and the 90 minutes figure would change.

By exclusion, they probably mean 16 tracks indeed.

Sony describes its Star Sphere project as a way to open space perspectives that have been previously limited to just astronauts and provide it to anyone on Earth via remote-controlled orbiting camera satellites.

https://petapixel.com/2023/01/05/sony-star-sphere-will-let-y...

"anyone on earth" might exclude those who cant pay the fee of...

Yes but now instead of having to spend $20 million on a satellite launch (including R&D time and hardware, not just the rideshare fee) you can pay $XX dollars to get your photo. Seems to be a significant cost savings.

I'm sure users from nations embargoed by whatever nation these images are sold from.

"Currently, this service is available only at Japan and United States"

https://starsphere.sony.com/en/

Well that seems to substantially ease restrictions on space photography. I assume the project is in response to the rule change that allows US satellite imagers to be approved if commercial images are available of the same type from another country. https://spectrum.ieee.org/eased-restrictions-on-commercial-r...

Not really. Airbus, a french company, is already providing high-quality satellite imagery. Based on the specs and the sample pic, I don't think this Sony thing is going to provide any useful imagery; its more of a fun artsy marketing campaign thing than something for serious use.

Just a month ago there was a startup announcement reselling satellite imagery to low-volume customers, and it raised fairly big comment thread. That thing has far better chance of democratizing satellite access https://news.ycombinator.com/item?id=34468644

I guess at some point we should expect a Sony SpaceStation.

Still waiting for the PS9. It gets delivered to your brain via nasal insufflation.

Cocaine is a helluva drug.

How can they constantly reorient the spacecraft for each shot without quickly running out of propellant?

Nevermind, I guess they only need to use the gyros for changing attitude.

Just a nitpick: they are reaction wheels (which work on the basis of conservation of angular momentum), not gyros (which work on the effect of gyroscopic precession).

Could you explain further please.

Angular momentum is conserved. If you're in space, and subject to no outside forces, and start off stationary... while you spin a wheel one way, you move in the other way (an equal and opposite reaction). When you stop the wheel, you stop. These are called reaction wheels. (There's also reaction spheres, etc.).

A control moment gyro works on a different principle. They're big (generally only used on space stations) but more versatile and power efficient. They are a wheel spinning quickly. A motor "tilts" the wheel and the resultant gyroscopic force imparts a torque to the station.

https://en.wikipedia.org/wiki/Control_moment_gyroscope

https://en.wikipedia.org/wiki/Reaction_wheel

Does this mean you'd always need three reaction wheels (or possibly just two?) to be able to orient in any direction, or is a single wheel itself able to orient to face different directions before activation, to achieve the same thing?

Two wheels, or a movable wheel, or a "ball" that you can actuate in two directions do it.

Of course, you probably also have thrusters (to "spin down the wheels" when they accumulate speed from outside forces), magnetorquers, passive stabilization mechanisms, etc.

Magnetorquers, very interesting - electromagnets that couple with the earth's magnetic field to assist with attitude/stabilisation:

https://en.m.wikipedia.org/wiki/Magnetorquer

Yup. There have even been satellites that have used only passive stabilization--- a permanent magnet + dark/light surfaces that spin it up from photon pressure.

And even more entertaining, these are off-the-shelf parts at this point.

https://www.cubesatshop.com/product/isis-magnetorquer-board/

Very interesting, the reaction wheel is obvious but to the gyro is not.

I can't see any efficiency problem though, electrical spin-up and spin-down with regenerative braking should reclaim the energy. I'll read the wiki article. Thanks.

> I can't see any efficiency problem though, electrical spin-up and spin-down with regenerative braking should reclaim the energy.

A lot of uses of reaction wheels requires them to constantly spin because there's been an outside force applied. The wheel mass also tends to be low because it's divided between multiple axes and so speeds of wheels need to be pretty high.

> with regenerative braking should reclaim the energy.

Nah. You start braking, you start spinning again. You have to combine that with thrusters, which means you are probably braking pretty quickly.

If the wheels have not accumulated steady rates from outside forces, you spin a wheel and move while it's spinning. Then you stop the wheel and stop. That was the (trivial) case I'd described that the person you replied to is responding to.

It likely has reaction wheels and magnetorquers on board for attitude control. The propellant is only used for orbit raising.

raising and lowering. sometimes, you have to move your bird out of the way of something else. with enough notice, you speed up or slow down to change altitude cost effectively. direct lifting in altitude is expensive in use of fuel

I think you also use propellent to reset the reaction control wheels when they run too quickly.

I believe that's the reason for the magnetorquer? There should be very little reason for a satellite to build up angular velocity beyond very small imbalances like from atmospheric drag. The needle of a high quality compass seems to have plenty of torque. It probably used propellant initially, though.

Using the propulsion system frivolously could even be detrimental for various reasons. Depending on what it is, it could cause degradation to parts of the satellite like its optics or solar panels. During scheduled thrusts, the satellite could have to orient mechanisms a certain way or close an aperture.

Prior to 2023, I didn't know a single company that offered these satellite services to consumers, but recently a startup launched with similar service: skyfi.com

I noticed Carmack was giving them helpful feedback

https://twitter.com/ID_AA_Carmack/status/1626389607104249857...

(I know this isn't about Sony, just commenting fwiw based on the timing really)

It would be nice to pair this with PSVR2

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