The Moon and Planets

[Eric Mc]

I think it would be nice to have a thread for discussion of the above. At the moment they tend to get discussed in the context of specific space probe missions or even dumb conspiracy theories.

However, they are interesting bodies in their own right and we could discuss the various probes, landers, rovers etc all in one spot.

For example, this morning the Chinese managed to safely return the first ever rock samples from the moon's far side.

[Desiderata]

Great idea Eric, I've nothing to contribute at the moment, but following the thread now.

[peterperkins]

I note Dr Ed Stone the leader of the Voyager 'Grand Tour' Project passed away recently.

A brilliant scientist/leader by all accounts.

Both spacecraft are still alive even today, slowly leaving our solar system behind for the long journey between the stars.

https://www.jpl.nasa.gov/who-we-are/faces-of-leade...

[Eric Mc]

He was a regular on the various BBC Horizon programmes that covered the Voyager missions and other NASA space probes.

I would also like some chat on the moon and planets themselves i.e. what are they like atmosphere and geology wise and how they interact with each other etc.

[Custerdome]

An interesting topic, and especially with the discovery of more and more exoplanets our own back yard is now seen to contain a few yardsticks.

A good book I read recently was The Red Planet, by a geophysicist/geologist (Simon Morden), who gives us a "natural history of Mars" . There's inevitably a lot of supposition, but it's a good read, some of the physical facts are still eye opening.

A little further back I remember going to an exhibition at the NHM (I think) called Otherworlds, a collection of pics of the planets, accompanied by a specially written soundtrack by Brian Eno. Seeing some of the imagery in a (very) large format and moody lighting was indeed impressive, some of it going back to the Grand Tour mentioned above. A new take on old images, always worth a view imo.

Not so much our Moon, but other moons in the solar system seem to be giving up more and interesting data, with a few amazing projects being planned or talked about. Maybe it should be The Moons and Planets Eric?

Does anyone know if China will be releasing any of the sample they brought back yesterday to the West?

[Eric Mc]

Even our moon throws up surprises. The discovery of water on the moon just over 20 years ago was not expected at that time - after the original analysis of the Apollo samples indicated that the moon was very dry. It turns out that the Apollo samples did indeed contain evidence of water but it took more modern analytical techniques to find it.

On Radio 4 this morning they said that for the first two years, the samples returned today will be exclusively available to Chinese scientists only but after that some samples will be distributed to other countries' labs.

[Simpo Two]

Eric Mc said:

Even our moon throws up surprises. The discovery of water on the moon just over 20 years ago was not expected at that time - after the original analysis of the Apollo samples indicated that the moon was very dry. It turns out that the Apollo samples did indeed contain evidence of water but it took more modern analytical techniques to find it.

Could Apollo have landed men on the far side of the moon?

[Super Sonic]

Simpo Two said:

Could Apollo have landed men on the far side of the moon?

I think they could, but they would be unable to communicate with us, so no live pictures etc.

[Eric Mc]

Simpo Two said:

Could Apollo have landed men on the far side of the moon?

Technically yes but there would have been a number of additional issues that would have needed to be addressed.

The main one was communications. Without some sort of relay satellite, it is impossible to maintain radio contact with an object on the far side of the moon - whether the object is in lunar orbit or on the surface. A relay satellite of some sort is required. It could have been technically done between 1968-1972 but NASA's budget for the lunar landings had never anticipated the need to land on the far side, so no work, as far as I am aware, was ever carried out in designing a relay satellite.

Having said that, Dr Harrison Schmitt, the Lunar Module Pilot on Apollo 17 and the only qualified geologist to walk on the moon, made a real nuisance of himself in the Astronaut's Office by lobbying hard for a landing on the far side. However, he was told to shut up about it or he'd get bumped off Apollo 17 - so he calmed down.

The Chinese now have a relay satellite at one of the moon/earth/sun Lagrange points which allows radio signals from their far side landers and rovers to talk to earth.

[WrekinCrew]

Super Sonic said:

Simpo Two said:

Could Apollo have landed men on the far side of the moon?

I think they could, but they would be unable to communicate with us, so no live pictures etc.

Would there have been some times when the orbiting Command Module could see both the lander and Earth, and acted as a relay?
I guess it depends how far into the far side they landed.

Edited by WrekinCrew on Tuesday 25th June 11:23

[epom]

Timing is everything. My 6 year has taken an absolute fascination with Space and Planets in the last few weeks. Enthralled by it. Learning a lot myself also. Our Universe was a great watch.
Post anything interesting

[Eric Mc]

WrekinCrew said:

Would there have been some times when the orbiting Command Module could see both the lander and Earth, and acted as a relay?
I guess it depends how far into the far side they landed.

Edited by WrekinCrew on Tuesday 25th June 11:23

The answer is yes - but the window available to act as a relay would be very short. Some of the crucial steps in a near side lunar landing actually happened on the far side, out of communications with earth. For example, it was usual for the Lunar Module (LM) and Command Module (CM) to perform the pre-landing separation manoeuver on the far side. So normally the Command Module would emerge from behind the moon a few minutes earlier than the Lunar Module, which would be on its way down to the surface and at a lower altitude. In those circumstances, the CM could start communicating to Mission Control a bit earlier than the LM and could be used as a relay. But the LM would establish direct contact with earth just a few minutes later.

[Tigerite]

I'm quite fascinated by Quaoar's rings, which they have no idea how didn't coalesce into a moon, given their distance from the (dwarf) planet.

[Eric Mc]

Not heard of that one. Have you any pictures?

[Simpo Two]

WrekinCrew said:

Would there have been some times when the orbiting Command Module could see both the lander and Earth, and acted as a relay?

It could have received data from the lander and relayed it when it emerged. Or NASA could have launched a lunar-stationary comms satellite for the job - compared to the manned mission it couldn't have been that hard to do. Is live data from the surface actually essential to a mission or just a useful bonus?

Edited by Simpo Two on Tuesday 25th June 20:06

[Eric Mc]

But since they never planned a far side landing , it was never considered,

[SpudLink]

The European Space Agency previously said radar signals indicated there was possibly a large liquid water lake under Mars' ice cap.
Research now indicates it is more likely to be variations in the ice, rather than liquid...
https://www.telegraph.co.uk./science/2024/06/07/ma...

[RizzoTheRat]

For those interested in such things, I highly recommend Astronomy On Tap.
In the UK there are events in Edinburgh, London and Portsmouth, and a lot of them live stream on Youtube or Zoom as well. They're free events in a pub once a month with a couple of talks from astronomy post docs and PhD students. We quite often go to our local one in Leiden and recently they've had several talks on exoplanets, planetary formation, and one on selecting potential landing spots on the Moon.

https://astronomyontap.org/locations/?tx_post_tag=...

[Eric Mc]

SpudLink said:

The European Space Agency previously said radar signals indicated there was possibly a large liquid water lake under Mars' ice cap.
Research now indicates it is more likely to be variations in the ice, rather than liquid...
https://www.telegraph.co.uk./science/2024/06/07/ma...

Ineresting - although from a practical point of view (i.e. human exploitation) whether it's frozen or liquid water isn't that big an issue.

[annodomini2]

Eric Mc said:

SpudLink said:

The European Space Agency previously said radar signals indicated there was possibly a large liquid water lake under Mars' ice cap.
Research now indicates it is more likely to be variations in the ice, rather than liquid...
https://www.telegraph.co.uk./science/2024/06/07/ma...

Ineresting - although from a practical point of view (i.e. human exploitation) whether it's frozen or liquid water isn't that big an issue.

Maybe a bigger issue than you think, on Earth everywhere there's liquid water, there's life.

IF life exists on Mars, may risk exposing people to something our biology cannot withstand.

Ice would theoretically be lower risk. (Also possible for frozen life in the ice of course).