I wonder how Apollo astronaut spend their time during their way to moon

[Sampa]

I imagine it would be a pretty intense role, being one of the first martian visitors. Managing the time delays will make media interaction interesting.

This is why I am a HUGE proponent for setting up satellite communications relays somewhere between Earth and Mars (or any other planet we want to visit) BEFORE we start sending crews

[Eric S]

Well, the thing with cancer it seems is that many things, high radiation exposure, contact with carcinogens et cetera increase slightly the odds that a given individual will get cancer, but if and when you get it it cannot really be traced to anything in specific. Astronauts will have higher probability to get cancer, but whether a given astronaut's cancer is caused by their time in space is not a clear thing to answer.

If I remember right, NASA's policies on radiation exposure basically limits an astronaut to enough radiation to increase the chance of cancer by 5%. I don't know if any astronauts actually reached that limit. There were multi-flight veterans, so one trip wasn't enough to hit that limit. In fact, I seem to remember that the total radiation from a trip to the moon and back was somewhere around what a full time airline pilot gets in a year.

[Guest]

This is why I am a HUGE proponent for setting up satellite communications relays somewhere between Earth and Mars (or any other planet we want to visit) BEFORE we start sending crews

It will only add more delays. Instead of speed of light delay, it will be

speed of light - data processing - speed of light - data processing - speed of light - data processing -

Additionally, relay sats cannot be arranged to be on straight line, so they will introduce geometry delays too.

[Sampa]

It will only add more delays. Instead of speed of light delay, it will be

speed of light - data processing - speed of light - data processing - speed of light - data processing -

Additionally, relay sats cannot be arranged to be on straight line, so they will introduce geometry delays too.

Who said anything about processing, just a simple relay like TDRS. We can process it on the ground! We just need a satellite system in place to bounce coms off to Earth!

[Guest]

If you do only "on the fly" retranslation, you will end up with pile of errors instead of original data stream. Even so, even simple analog amplifier introduces some delay. And distortions. And whatever type of relay sat you use, "broken line" vs "straight line" problem persists.

Retranslators only remove need for big and powerful transmitter on ship, but launching 100-1000 relay sats on heliocentric orbit is don't worth it for one mission. Or for several flag planting missions.

Edited February 24, 2015 by Guest

[cpast]

The comms delay is because signals only travel at the speed of light, which is finite. That's the only problem; the issue isn't being able to communicate with Earth (that happens only around every 1 month in 26), it's that it takes time (4-24 minutes) to do so.

[Bill Phil]

The big issue for Mars missions is that you're going to have A LOT of time on your hands. Books, movies, and other forms of entertainment are a good way to pass the time. And you can even upload new books and movies/shows while a Mars mission is in flight.

Not to mention that you're going to need a few tons of food per person...

On Apollo, they had a lot of routine maintenance to carry out on the spacecraft. Realigning the navigation devices (with a sextant no less!) and checking equipment. Beyond that they had to film stuff for the press, they had to talk to NASA, and they ran experiments. Probably some other method, too. Maybe a book or two...

[Newt]

There were multi-flight veterans, so one trip wasn't enough to hit that limit. In fact, I seem to remember that the total radiation from a trip to the moon and back was somewhere around what a full time airline pilot gets in a year.

A bit of investigation suggests that the Apollo crews would have received perhaps about 1% the radiation that airline flight crews get in a year, even long Skylab visits remain lower than a year on an airline. Of course a Mars mission would be markedly longer and more radiation ridden most probably.

That said, there are some suggestions that airline crews are at much greater risk to get melanoma than the general public, so flying like that may not be without some health impacts.

[PlonioFludrasco]

The big issue for Mars missions is that you're going to have A LOT of time on your hands. Books, movies, and other forms of entertainment are a good way to pass the time.

Personally, I'll carry a flash memory with a copy of KSP.

Think about it, flying a Duna mission while flying a Mars mission, making Jeb to play Human Space Program on a laptop and going to Mars,etc. Spaceception, basically!

[Sirrobert]

Personally, I'll carry a flash memory with a copy of KSP.

Think about it, flying a Duna mission while flying a Mars mission, making Jeb to play Human Space Program on a laptop and going to Mars,etc. Spaceception, basically!

Just try not to talk about how you crashed your lander.

Or how your ship got eaten by the Kraken

[PlonioFludrasco]

Just try not to talk about how you crashed your lander.

Or how your ship got eaten by the Kraken

[goldenpeach]

Just try not to talk about how you crashed your lander.

Or how your ship got eaten by the Kraken

Imagine being the LM pilot, saying, right before landing, "hey guys! remember all those lander I failed to land properly causing a lot of deaths?"

Just to reassure them

[Sampa]

Imagine being the LM pilot, saying, right before landing, "hey guys! remember all those lander I failed to land properly causing a lot of deaths?"

Just to reassure them

Me as the "other crewmembers" "LEMME OUT OF THIS THING!!!!!"

[Sirrobert]

Imagine being the LM pilot, saying, right before landing, "hey guys! remember all those lander I failed to land properly causing a lot of deaths?"

Just to reassure them

No, that's starter evil. A far more advanced version would be 'don't worry, I practiced with all those crashed landers. I'm sure it'll be fine now'

[goldenpeach]

Or another version: "don't worry guys, I practiced a lot of landings in KSP. and hey! I even made a successful one!"

[meve12]

If you do only "on the fly" retranslation, you will end up with pile of errors instead of original data stream. Even so, even simple analog amplifier introduces some delay. And distortions. And whatever type of relay sat you use, "broken line" vs "straight line" problem persists.

Retranslators only remove need for big and powerful transmitter on ship, but launching 100-1000 relay sats on heliocentric orbit is don't worth it for one mission. Or for several flag planting missions.

He didn't say a hundred. All we need is something like 6; enough to cover the entirety of the Mars surface.

The problem here isn't transmitting the signal to Earth, it's how to do so with a planet in the way. So you need relays sats in Mars orbit to bounce the signal around the planet before you can transmit to Earth.

[Nibb31]

Not really usefull. You only get a blackout at night, and presumably any manned Mars mission will have at least one MTV in orbit that would serve as a relay. Combine with the other orbiters (MRO and any future missions), and there really isn't any need for a communication relay network. You don't really need 24/7 coverage. Apollo had blackout periods each time they went behind the Moon and it was perfectly ok.

[Guest]

He didn't say a hundred. All we need is something like 6; enough to cover the entirety of the Mars surface.

The problem here isn't transmitting the signal to Earth, it's how to do so with a planet in the way. So you need relays sats in Mars orbit to bounce the signal around the planet before you can transmit to Earth.

I was meaning heliocentric relays, not Mars orbit relays.

Mars orbit relays are needed as you described, but they will not alter data delay in any significant way.

[Nibb31]

And why would a signal going through a heliocentric relay at some random location in the solar system go any faster than a signal traveling in a straight line?

[Guest]

And why would a signal going through a heliocentric relay at some random location in the solar system go any faster than a signal traveling in a straight line?

My point is, that it will travel slower, due to non-straight line and retransmission delays.

It was Sampa's idea, not mine.

[Sampa]

My point is, that it will travel slower, due to non-straight line and retransmission delays.

It was Sampa's idea, not mine.

First of all, it was just that, an idea. Second of all, i think we had better start getting back on topic according to the OP. Don't want to give the mods a reason to lock this thread.