NASA's 'Inspirational' Mars Flyby

astroengine writes "The idea of slingshotting a manned spacecraft around Mars isn't a new one. In the 1960's, NASA carried out a feasibility study into an 800-day flyby mission to the Red Planet. And it would have been awesome. AT&T/Bellcomm mathematician A. A. VanderVeen was working for NASA in 1967 and came up with 5 possible launch opportunities between 1978 and 1986 — two windows in 1979 and 1983 provided the shortest transit time between the planets. But launch mass and fuel requirements were a constant issue. So VanderVeen turned to physics to find an elegant, and scientifically exciting, solution: add a Venus flyby to the Mars trip. Mars, Earth, and Venus align with the sun five times every 32 years, but Venus and Mars alignments happen more frequently making double (Earth-Venus-Mars-Earth) or even triple (Earth-Venus-Mars-Venus-Earth) flybys a viable mission. Unfortunately, the flyby never happened."

Re:About launch mass

[DerekLyons]

I never completely understood the need of launching massive ships from Earth whenever we want to leave it. Whenever we wanted to travel the seas, we did not build a massive caravel inland then painstakingly dragged it all the way to the coast. We reasoned it made more sense to build it in a dry dock, that way it only requires a tiny push to get it into the ocean.

I can't tell if you're actually that stupid or if you're pretending to be stupid to make a point. I mean seriously, you can't grasp the difference between a shipyard (dry dock) that you workers can walk to and needs no especial support - and LEO where everything comes with a launch price cost tagged onto it?
 

Wouldn't anyone at NASA think that making a "Space Dock" made sense?. Make a bunch of tiny trips to lower earth orbit and build the ship there, so you can make a larger ships to travel further. Mass would not be such a big issue (granted, fuel would be), but at least the escape velocity problem would be non-existent.

No, space docks don't make any sense - they don't save you any money, in fact they cost you *more* because of the need to support your assembly on orbit. Mass is still a big issue because you have to pay to boost it. Escape velocity is still a problem, because you still need to boost the fuel to LEO and the mass of your spacecraft beyond LEO.
 
Yes, eventually we're going to have to face the on-orbit assembly issue, but we're a long way from that. We're still in the 'canoe' phase - which you *can* build inland and carry to the water.

Re:About launch mass

[FatLittleMonkey]

The problem is that working in space is hideously expensive. So that the cost of engineering out as much mass as possible to allow you to do everything in a single launch is, bizarrely, cheaper than launching a bunch of heavier-but-simpler-&-cheaper parts to assemble in orbit. For example, right now we can't even launch ship and fuel on separate rockets, which seems a pretty basic skill for a space-faring civilisation.

As we do more in orbit, particularly as private companies actually start operating human-space-flight (even if it's just to provide in-orbit services for NASA/DOD/ESA/JAXA/CSA/etc), we should see techniques developed to make operations in space cheaper. At some point we'll reach the cross over where assembly is always cheaper than single-launch. After that, someone will inevitably start building a "space-dock".

It's like reusable launchers. Logically, using a launch vehicle 100 times should be cheaper than using it once and throwing it away; look at aircraft, who would build a single-use plane? But so far we haven't been able to figure out how to make refurbishable craft cheaper than disposable ones.

Re:800 days without any possibly of escape

[Anonymous Coward]

Also worth bearing in mind: While the great unexplored destinations of the age of sail were far more forgiving than our neighbour planets, the technology and the level of human organisation was not.

- The people back then built amazing ships, but their construction methods were based on rule of thumb craftsmanship rather than highly-specced precision engineering.
- Ditto for materials. They had no ISO reassurance that a given beam of wood would stand up to the forces and stresses of a storm.
- Their crews weren't all well-motivated, highly-trained, hand-picked experts, but consisted largely of whatever uneducated drunks and kids they could trick on board.
- They had no idea of what was at the other end of their journey except a big "Here be Dragones" on a map. They usually didn't even know how long their journey would be.
- They had, at best, primitive understanding of nutrition, medicine, psychology and all the other associated sciences necessary to keep a crew functioning at peak performance on a long mission. 4 months into a sea voyage you could expect much of the crew to be dead, diseased, injured, malnourished, disgruntled and/or half-crazy to boot.
- They had no contact with home, no mission control, no robotic probes ahead of them or telescopes behind them sending them vital information.

Sure, we all know heroic stories of the explorers who went out and discovered something big and came back to tell about it, but how many unsung crews and ships were lost because they ran out of food in a windless sea, or had their ship destroyed in a storm, or maybe the ship just sank because of a flaw in the hull's materials or because some crew member didn't do their job properly?

Basically, they were winging it: Flinging themselves into the complete unknown with little more than a hope and a prayer. Modern space programs, on the other hand, can be meticulously planned and modelled and trained for to the last detail. Sure, unexpected things will happen, (probably a lot less than you might think) but we can plan for those as well.