>http://www.aas.org/~dps/decadal/whitepapers/jones_120701.doc provided by Robert in cased any interested missed it in the myriad posts below. I'd also say his outline back at: http://www.habitablezone.com/space/messages/18457.html does suggest an NEO mission in the range of 1 to 2 billion is plausible. I'm curious what he and others estimate human's to NEOs would cost.

Generic argument:

I'm sorry that the url to the decadal study was lost - next time, i'll identify it better. To spell out my argument again: to me, sending people to NEOs is a bit like extending the LEO envelope & needs to be budgetted as such; whereas going to Mars or the Moon is a substantiative space exploration program which has to be independently sold. We hear plenty about Mars (& the Moon) having real public interest, generally without any credible market research (internet surveys by the Planetary Society hardly count); but this interest has translated into any significant bucks anywhere except perhaps the PRC, which may or may not - being rather familiar with the country, my informed is: probably not - be spending money on a Moon program; & ESA, which has allocated a small amount for human spaceflight beyond LEO under the Aurora program (see ftp://ftp.estec.esa.nl/pub/columbus/aurora/index.htm). If Mark - or anyone - can actually sell a big mission anywhere he/they have my admiring support; but i truly doubt that this sales job can be done with the budgets required for missions with near term technologies. That's why is started looking at an option which wasn't as hard a financial sell. The converse of this is also true: if NEOS >can't< be reached cheaply with basically OTS technology, i'm walking on; but for the reasons given below, i'm fairly confident that they can. That said: i don't >really< believe that a mission in the US$1-2b (even with massive Russian support) is really feasible (politically, if on no other level)... a figure in the realm of US$10b spent over about ten (or less) is much more reasonable. In cf, this is less than half what NASA currently spends on shuttle flights to LEO. The Caltech plan called for US$80b over the same time period, which is more than NASA spends on space in total each year... a major price differential between the two approaches.

Flysby:

The generally quoted value of a Lunar flyby - my maths isn't good enough to confirm - is about 1kmps; & a Lunar/Earth flyby trajectory from GTO can easily turn 2kmps worth of burn into 9+kmps worth of c (i can give you some paper urls with a couple of days' planning; but not off the top of my head), more than you need to get you into a solar orbit with Earth return, the basis of this mission. More oomph is needed to get there from LEO, of course - i think about 2; but you're really stretching my limits at doing orbital mechanics.

Targets:

A rule of thumb for identifying possible targets is to look at the relative velocity when an object makes a terrestrial flyby. This can be taken from Ron Baalke's NEO page & elsewhere; & reveals a solidly expanding chunk of objects with single digit relative vs. More work needs to bedone by real orbital mechanicists to choose the best targets. however - some of which has already been done in respect of robotic sample return missions such as MUSES-C & the unfunded AROS & Hera (i have some calculations at home; & can supply if really pushed).

Also - & thanks to a Mr X (i don't know if the peron in question would like his name publisghed openly in this context; but i would source name privately) - i have some rough delta v figures for targets such as Nereus at home; & - if really pushed - could dig up 90 (his count - i took his word) targets with a direct throw (ie, no GAs) of less than 6kmps to rendezvous from LEO. These figures - which would be reduced with GAs, of course - are more than a year old, though; & there are undoubtably a lot more (like 2002 AA29) in the big LINEAR surveys. Translating rendezvous delta v to return delta v is beyond my mathematical skills, though.

Technology:

Solar power can carry the mission without modification because all the best targets are in near terrestrial space; & closed loop life support can currently handle quarterly periods fairly comfortably; & the longer periods have also been demonstrated in LEO. 12 months worth of life support would cover a good Lunar mission & most NEO targets (but not a Mars mission; which requires demonstration of a closed loop system for a free return flight - ie, Earth/Mars/Earth, with no landing). This can be demonstrated using MIR-2 class technology in LEO, of course. We know that people can survice a years worth of microgravity already; & given that the target object in this case is itself a microgravity environment & that our astronauts will be returning to Earth (where our best medical technology will be waiting for them), artificial gravity would be unecessary for a year long NEO mission - something which provide a good test whether it's really necessary for Mars, as a useful aside. A more ambiguous life support challenge is radiation shielding, which will be needed for all missions beyond LEO, with the level of technology development required for all three targets pretty much the same. No landing technology is required in a microgravity environment (even bump landing an empty craft on the surface of the target object could be done with simple thrusters), which does away a major expense from the Mars/Lunar alternatives; but reentry is a definite challenge. NEOs would generally require entry velocities greater than a Lunar (& LEO, of course) return; but less than Mars return - the one technological issue where an NEO mission is beaten by either of the carryover champ concepts.

Assuming a conservative 1/5 mission/fuel ratio, a 20mt mission module with 100mt worth of fuel can be lifted on six Proton class boosters. This would be a tricky docking manouevre; but cutting the weight of the module (MIR-2 class units are actually half the schematic size) & bearing in mind that the fuel ratio chosen is actually taken from some Mars mission architectures, suggests such a more competently put together architecture than i capable of doing should be flyable with three or at most four Proton-class flights (especially if the rockets could be flown from equatorial locations such as Christmas Is & Sea Launch). A Soyuz-class mission would be required to crew the ship; & probably more than one Progress-class flights for supplies; but there are no obvious dealbreakers for a mission in the less than US$10b price range; which makes for a damn exciting prospect.

That the NEO alternative needs to be studied properly is obviously - what it doesn't is the gutcheck response on instant dismissal as not ideal which it generally gets; &, which you began with (although you're more recentb posts have shown that you have grown more considerate ogf the concept).

Robert