[QUOTE=Cymro]
Hmm … suppose some immensely powerful alien superweapon is discovered by a robotic probe. Not only is it set to fire on earth and could do so at any time, but will offer total world domination to whoever gets their hands on it.
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:dubious: Where exactly are you getting this . . . ahh . . . ahem . . . completely hypothetical or else totally spurious information?
Please provide names and addresses.
[QUOTE=robz]
Minor question sparked by “Stranger on a Train”'s excellent post above.
Re the atmospheric braking manuver at Jupiter. Does Jupiter present a radiation hazard itself? I think I remember from somewhere something about dangerous radiation belts around Jupiter.
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Yes, there is extremely high levels of ionizing radiation around Jupieter. Cassini found that radiation conditions harsher than originally thought and the Galileo probe had a substantial number of radiation anomolies from unanticipated radiation levels. There’s also a very large and powerful flux tube betweem Jupiter and Io as a result of the plasma torus created by emissions from Io trapped in Jupiter’s magnetic field. This pumps the magnetosphere of Jupiter well above the normal levels of charged particles it would trap from solar wind and interstellar space. So you’d definitely need to shield from this. Fortunately, except in the most intense areas, the bulk of the radiation is in the x-ray and low-power gamma radiation area of the spectrum, and therefore only a moderate level of shielding is necessary. High energy gamma radiation should be managable (mostly by avoiding the Van Allen-like belts around Jupiter whenever possible, and generally staying outboard from Io’s orbit) and neutron radiation should be slight to negligable. The more difficult part is protecting the guidence and control systems from intense magnetic flux, which is definitely a nontrivial problem. So, you’d want to do your aerobraking maneuver very quickly and then get the hell away from the inner Keplerian system.
Putting an engine on the ISS and flying it to Jupiter is the next thing to impossible, and about the poorest plan you could come up with even if it were. There’s essentially no radiation shielding in much of the station, it isn’t designed to take more than a small amount of thrust for a short period of time for stationkeeping purposes, and is otherwise unsuited for interplanetary travel. Boosting up a sealed vessel for habitation is about the least of the difficulties in getting to Mars…there’s no reason to complicate plans by integrating a kitchen sink into the mix just 'cause it’s already up there.
Stranger
[QUOTE=Stranger On A Train]
Putting an engine on the ISS and flying it to Jupiter is the next thing to impossible, and about the poorest plan you could come up with even if it were. There’s essentially no radiation shielding in much of the station, it isn’t designed to take more than a small amount of thrust for a short period of time for stationkeeping purposes, and is otherwise unsuited for interplanetary travel. Boosting up a sealed vessel for habitation is about the least of the difficulties in getting to Mars…there’s no reason to complicate plans by integrating a kitchen sink into the mix just 'cause it’s already up there.
Stranger
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The ISS was Sapos suggestion after commenting on my reason for getting there. Since there is no off the shelf vehicle available, any fast mission to mars is going to involve a hybrid composite thats going to be made up most likely of parts that have been gathering dust in museums for the last 3 decades.
All components by themselves will be man rated , but the ship as a whole will not be. Also I believe that in defense of my mission reason, its going to be the first of alot of ships heading that way, both manned and robotic.
Declan
[QUOTE=Declan]
The ISS was Sapos suggestion after commenting on my reason for getting there. Since there is no off the shelf vehicle available, any fast mission to mars is going to involve a hybrid composite thats going to be made up most likely of parts that have been gathering dust in museums for the last 3 decades.
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Sorry, I didn’t mean to misattribute you.
Those “parts that have been gathering dust in museums for the last 3 decades” are not going to cut it for use, even improvisationaly. Even cutting out the bureaucracy, issues with aging and pedigree would make most stuff (say, Apollo-era hardware) unusable, and all of the support and maintenance equipment, plus many of the detail plans, are probably lost or destroyed. As someone who makes a living out of helping to refurbish and use decades-old, decommissioned rocket motors, I can assure you that trying to use equipment that has long disappeared from operational status with no aging and surveillence program is going to be more expensive and less trustworthy than just fabricating new.
A signficant amount of the technical difficulty of building a manned spacecraft are the thermal protection systems used for re-entry, hence the adoption of a blunt cone arse-first heat shield for the CEV/Orion replacement for the shuttle; it’s tried and proven, relatively cheap and easy to build and refurbish, and doesn’t require delicate, bleeding each material technology. Another are launch abort safety systems which are intended to give the crew a way to evac during and immediately after launch. In all honesty, these systems offer at best a marginal chance of successful escape during the early stages of boost. Eliminating these two systems and adopting a more risk-accepting stance regarding safety (i.e. we can’t prevent every possible problem, so we’ll focus on those that fall within a three sigma level of possibility) would dramatically reduce the cost and often unnecessary complexity of a vessel. Now you’re left with a habitat, shielding, power, provisions & recycling, shielding, and GN&C (guidence, navigation, and control). With the exception of propulsion and provisions & recycling, those are all soluable (given a sufficiently large bank account) with existing technology, and if you’re willing to accept the risk and hardship of a slow, lugubrious low-energy Hohmann transfer, you could get to Mars with only very modest extenions of existing technology.
I seriously doubt, however, that anyone can come up with a justification for needing to do so on short order that doesn’t amount to science ficiton, i.e. aliens, monoliths, et cetera. Even an incoming planet-killing meteor would be best dealt with one or more unmanned probes carrying large nuclear weapons or nuclear pulse rockets that would push the object out of the intercept course.
Stranger