Our dream for a space mission is:

A small robotic outpost on the Moon, with all sorts of gadgets and building blocks.

Then, kids from all around the world, working with real scientists, perform remote experiments using the robotic outpost. When we say "working with real scientists", we mean this literally. The real scientists shift gears and mentor the kids using the Socratic method. ([URL="http://en.wikipedia.org/wiki/Socratic_method#Harkness_education"]Or this.[/URL]) The real scientist probably can guess the outcome, but it is much more important for the child to discover the outcome and to feel that sense of discovery.

The result generates interest in the field and gets kids involved. (The biggest goal!)

Imagine a catapult contest between teams of kids. Seriously!

It also establishes a base on the Moon. As experiments get more complicated more stuff is sent to the outpost. After a few years we have a bunch of stuff up there, chosen for reliability and endurance, to maybe begin supporting a manned outpost.

We were, until recently, heavily involved in model rocketry. It is unfortunate that this hobby is so neglected today.

When we think back on our life we remember the big "Aha!" moments, and they are all related to independent discovery, whether guided or not. (Quite a few of ours were independent discovery after miraculous survival!)

:smile:

Hot air ballooning.
 

Not sure that budgetary constraints would allow this one, but it may be worth exploring further.

Fly a hot air balloon in the Jovian atmosphere. Standard trip to Jupiter, followed by aerobraking for stopping in the stratosphere. Drop what's left of the thermal protection, unfold the envelope and inflate by burning an on-board oxygen supply. Keep topped up by the waste heat from a small fission reactor which also provides the science and communications package with oodles of electrical power.

Not sure whether a comsat in high-Jovian orbit would be needed --- that's part of the cost constraint, but not the <= 2 launches constraint.

The main probe should fit on a Ariane-5 or its near-future upgrade.

[QUOTE=xilman;322795]Fly a hot air balloon in the Jovian atmosphere.
...
The main probe should fit on a Ariane-5 or its near-future upgrade.[/QUOTE]
I like this one.
But why not use a Falcon Heavy? The best Ariane-5 gets you 11,200kg to GTO for an estimated $120M. The Falcon Heavy will get you 19,000kg to GTO for a fixed price of $128M.

BTW, the budget of $1B is a soft number. Stretch it but don't break it.

Time to start moving the planets. We might need them.

A craft of maximum mass that repeatedly slingshots Venus and Mars, thus bringing them nearer to the Earth. Shouldn't take too long.:tu:

Not close enough to disturb the moon mind, and someone will tell me it's impossible anyway. (More planets required?)

or, more seriously:

Mars-style rovers at the moon's poles looking for water etc. The start of a long-term plan to make use of the moon as a base for longer missions.

A lander/rover that rides a periodic comet. Should stay gravitationally attached despite any melting? Use the emitted gases as fuel or process the 'ground'? Don't know if it is possible to match the orbit to get on board in the first place.

These just need the details fleshed out!

(As is the nature of mega-projects maybe we should consider $1bn an underestimate just to get the funding. We can multiply by four or something?)

[QUOTE=Uncwilly;322818]I like this one.
But why not use a Falcon Heavy? The best Ariane-5 gets you 11,200kg to GTO for an estimated $120M. The Falcon Heavy will get you 19,000kg to GTO for a fixed price of $128M.

BTW, the budget of $1B is a soft number. Stretch it but don't break it.[/QUOTE]The A5 is a proven launcher.

The forthcoming upgrade raises the maximum payload significantly.

I definitely think we need an un-manned mission to the moon. Haven't read up on this particular topic recently, but there are probably dozens of different goals we could try to achieve.

Seeking water at the poles, digging into the soil(is soil the proper term in this instance?) to see what we can find underneath, seismic studies, mining(if we can find a place super-dense with valuable metals or minerals). All sorts of awesome things we can do on the moon.

The only reason for a manned mission is to appeal to stupid people. You do science, a few people are impressed; but you send a person there, every Tom, Dick and Harry wants to know about it. Intelligent people will be interested in a manned mission for sure, but NASA had them hooked anyway.

[QUOTE=jasong;322837]mining(if we can find a place super-dense with valuable metals or minerals).[/QUOTE]
If we ever get fusion figured out, I've heard the moon is chock-full of helium-3.

[QUOTE=Dubslow;322857]If we ever get fusion figured out, I've heard the moon is chock-full of helium-3.[/QUOTE]You've been misinformed.

AFAWK, the top few centimetres of the lunar regolith contains a tiny amount of helium captured from the solar wind. A tiny fraction of that is [sup]3[/sup]He. Extracting the [sup]3[/sup]He would be very expensive. About the only things to the advantage of mining lunar helium is that the moon presents a large collecting area and it's been collecting the solar wind for a loing time. The moon is relatively close by at the bottom of a relatively gentle gravity well but collectors in earth orbit are even better in those respects.

The atmospheres of the gas giants, on the other hand, contain several per cent helium at a pressure or temperature of anything you would like, within reason. They are a long way from here but that impacts only latency, not capacity. The disadvantages are their ferocious gravity wells and the lack of any solid surface which you didn't bring with you.

Did you not realise that I had an ulterior motive in suggesting a mission for a long-term exploration of the Jovian atmosphere?

[QUOTE=chappy;322776]I suppose it would be out of line to suggest that NASA should send a craft to the nearest star: Sol.[/QUOTE]
There have been discussions about this. The idea has been floated, but there is no current mission being planned. I like this one.

Another mission that has been talked about, but not currently in the works that I like:

An asteroid deflection mission. There are suggestions that a practice mission be undertaken so that we can learn how well it might work.

There is a mission planned to the Sun: Solar Probe Plus [url]http://solarprobe.jhuapl.edu[/url] being built at JHU APL to launch 2018. Interesting trajectory with repeated Venus flybys to lower perihelion to 0.04AU.