how big with a spacecraft (hypothetically) have to be to get humans to Mars?

Question

it seems NASA are dead serious on getting humans to Mars in the 2030s. theres a saucer test happening tomorrow.

https://uk.finance.yahoo.com/news/nasa-wants-send-humans-mars-143700534.html

http://uk.businessinsider.com/nasa-mars-radiation-challenge-2015-5?r=US

BUT what I am chiefly interested in is the SIZE. the article says a ship will need to be much bigger than anything constructed before (which is obvious). so just how big will this ship have to be to logistically support such a long mission. and can we build radiation-proof insulation into it.

**NO boring answers from the resident sceptics please or you will be reported. don't want your pessimistic platitudes polluting my thread.

Cheers

Answer 1

In the 70's, when it was proposed as a natural follow-on project to the lunar landings, there were about 10 different designs; the best (IMHO) were the dumbell-shaped ones that rotated, creating artificial gravity. They were connected in the center by a control module, and that went to a 'garage' with two (possibly 4) landing vehicles - estimated at 140 tons, and would take 12 Saturn-V launches to get the bulk vehicles in orbit, and *that* would be married to a booster to send it to Mars. The crew would go to Mars in a small space station, basically.



Robert Zubrin proposed one in the late 80's - with all off-the-shelf technology, of getting us to Mars inside 10 years, with a single landing vehicle, and the command vessel was about the size of a mini-van. I believe his proposal took 5 shuttle launches (might've been 7) - and required a separate 'crew return booster or vehicle' to enter Mars orbit first, and wait for the manned mission to arrive.



The first method was going to be VERY expensive, but provided the crew with relative luxury... the second method - can you imagine 15 to 18 months living in a minivan with 6 to 8 others...? While it *could* be done... I wouldn't want to be one of the astronauts.

Answer 2

Random comment: there is no such thing as "radiation-proof insulation" when it comes to ionizing particles (cosmic rays, solar protons). It's a statistical thing - suppose an inch of material stops, on average, half the particles then two inches will stop half again i.e. 3/4 in total. It never reduces to zero, all you can do is to reduce the flux to an acceptable level. We still get cosmic rays here, all the time - particles are zipping through your body right now.

One proposal is to use the food stocks as a radiation attenuator, and as that runs down, sealed bags of poop. Since solar proton events are rare and can be detected/anticipated, a smaller space could be configured with thicker shielding (the water tanks perhaps) as a storm shelter into which everyone squeezes for a few hours.

Answer 3

60 feet long (18 meters) and 16 feet (5 meters) in diameter

That's not including the command module where astronauts sit during launch and re-entry



Have you ever gone somewhere on your holidays ??

Somewhere a bit remote ??

And stocked up at the supermarket so you don't need to bother about shopping when you are on your holiday



I have. We packed our car clear up to the roof inside -- plus a roof rack -- plus a trailer -- good for our 3 week trip.

The heaviest thing we packed was water (for drinking, cooking and washing) because none was available at our destination

But :

a) there was no room (at all) inside the vehicle to move while we were traveling.

but no matter -- we could (and did) stop every few hundred miles to "stretch our legs" and go to the loo

b) we still had to buy fuel on route to our destination -- and on our way home after the trip

c) we still bought extra food while we were traveling



The Mars astronauts have to take EVERYTHING with them.

That includes all food, all water, all air and all fuel , and every needed thing.

One needed thing is a space for astronauts to relax and exercise ...

and that area needs to be relatively spacious.



So i'm thinking --- something similar to the moon missions

A command module -- used at lift off and re-entry

A service module -- containing battery power, air bottles, some water and perhaps some food

A lander -- if astronauts intend to land on Mars.

and something the Apollo missions didn't have ...

A recreation module -- containing more food, water and air bottles



I keep hearing about a "heavy lift" rocket that will take all the stuff into low earth orbit. ---

I doubt if all needed things for a Mars trip could be lifted by a single rocket.



Assuming an orbit and return trip -- then no lander is required.

But both the service module and the recreation module are going to have to be at least 30 feet (9 meters) long and 4 perhaps 5 meters in diameter

And unlike on the Apollo moon missions, I envision the service module will be pressurized so as to provide an extra area for astronauts to exercise in and to allow inspection / adjustment whilst in flight.



Did I mention anything about facilities for recycling water ??

or for growing food hydroponically ???

Answer 4

Those are good answers. Total radiation shielding is not possible, but average radiation can be about the same as average sea level on Earth if the passengers stay in the tiny heavily shielded area during solar storms.