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Chang'e 6 lunar sample return mission returns with samples from moon's far side

theguardian.com

111–120 of 129 posts

Re: Chang'e 6 lunar sample return mission returns with samples from moon's far side

#111

Earlier quoted context omitted.

> nuclear power plans by Russia not so much Why? Any lunar base without nuclear power plans is not a serious effort.

I often wondered, how do you deal with all the waste heat from a fission power reactor, in a vacuum? Giant radiators? edit: fixed typo, derp. fusion=fission

maybe not so hot indeed due to the scarce air that's why it's so cold at night on the moon. Only turn on the reactor at night to generation and use capacitors at day?

Re: Chang'e 6 lunar sample return mission returns with samples from moon's far side

#112
post #89

Earlier quoted context omitted.

Here's an article on DIMES, the system JPL developed in the early 2000s to address the problem of estimating horizontal velocity for the Mars landers: https://robotics.jpl.nasa.gov/media/documents/DIMES-ai-space... Martian winds make this more important there than on the Moon. The DIMES system integrates radar, visual images, and IMUs. They did not have a dedicated Doppler radar for horizontal velocity, for technical…

ALHAT/LVS problem seems to be the overly broad requirements, it's overengineered (hence the modularization in LVS) which led to long delays during the development. For comparison, Chang'e 3 TRN solution was dead simple, it was roughly speaking a webcam combined with the specific lighting angle during the landing. Then they iterated on it in subsequent missions, creating a decent system that was less dumb and restrict…

Interesting that its mostly image/ video processing, which isn't a 'traditional' guidance/control approach.

Re: Chang'e 6 lunar sample return mission returns with samples from moon's far side

#113

Earlier quoted context omitted.

I often wondered, how do you deal with all the waste heat from a fission power reactor, in a vacuum? Giant radiators? edit: fixed typo, derp. fusion=fission

maybe not so hot indeed due to the scarce air that's why it's so cold at night on the moon. Only turn on the reactor at night to generation and use capacitors at day?

You can't really turn fission reactors on and off, they're always producing decay heat even if not being used for power generation. But why not radiate the excess heat into the crust of the moon with a subsurface loop, kind of like a ground source heat pump.

Re: Chang'e 6 lunar sample return mission returns with samples from moon's far side

#115
post #2

The international moon base plan is fascinating. https://en.wikipedia.org/wiki/International_Lunar_Research_S... (nuclear power plans by Russia not so much) Is there enough gravity on the moon to prevent the long-term health problems from the space station like bone, muscle and vision loss?

Radiation is going to be a bigger problem, which calls for a deep underground base, which I'm suspecting it coincidentally also enable centrifugal artificial gravity

Re: Chang'e 6 lunar sample return mission returns with samples from moon's far side

#116

Earlier quoted context omitted.

> nuclear power plans by Russia not so much Why? Any lunar base without nuclear power plans is not a serious effort.

Solar PV linked to battery storage is the obvious energy source for a moonbase. All reactors require coolant circulation and water is going to be among the most valuable commodities on the moon, not something you want to circulate through a reactor (where you inevitably get tritium formation, making the water unsuitable for other uses). Maybe you could use helium or liquid sodium metal as the primary coolant, but the…

Solar PV battery combo is just a giant spatial transmission line system for a fusion reactor. For high density applications, fission and/or fusion make more sense.

It's just that we're close enough to the Sun, and that a lot of us are living in low-density residences.

Solar ray density reduces to half of what we get on Earth on Mars our closest outer planet, simply from inverse square law. And deep space people always said it goes down so fast a space nuke is a hard requirement for Jupiter and beyond. There might be ways to make it work on Moon, but PV plus battery is just rural inner planets thing, not the way forward or anything. It's just temporary hype technology.

Re: Chang'e 6 lunar sample return mission returns with samples from moon's far side

#117
post #3

What are they expecting to be different about samples from the moon's far side to those previously collected?

The reason you seek to explore what you don't know is because you don't know what you don't know. In general I don't think people really appreciate how ridiculously little we know about everything outside of our planet. Like for instance it was only in 2013 (!!!) that it was discovered that Mars' soil is relatively 'moist', about 2% water by mass. And that's just the topsoil layer - it's suggestive that below the sur…

> The reason you seek to explore what you don't know is because you don't know what you don't know.

In theory yes, in practice it's never the case, you have to justify hard why you want to do the experience and what you expect. Especially with multi million dollar experiences like these

Re: Chang'e 6 lunar sample return mission returns with samples from moon's far side

#118

Super impressive. A return mission from the far side is very technically difficult, and pulling it off paves the way for a staffed lunar lander on the far side.

How is it more difficult than return from the near side, besides the need for a relay?

Re: Chang'e 6 lunar sample return mission returns with samples from moon's far side

#119

Earlier quoted context omitted.

I often wondered, how do you deal with all the waste heat from a fission power reactor, in a vacuum? Giant radiators? edit: fixed typo, derp. fusion=fission

maybe not so hot indeed due to the scarce air that's why it's so cold at night on the moon. Only turn on the reactor at night to generation and use capacitors at day?

The day is 28 times longer than on Earth. You'd need very big capacitors.
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