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Delaying Our Visit To The Last Planet
O.F. Fascist writes: "Story over at Space.com about how the first NASA mission to Pluto might get cancelled for a variety of reasons." Sounds like the reasons at play here are good, though -- "reliable transport required" applies to multi-year interplanetary journeys, too. (And what are we looking for on Pluto again?)
Christopher A. Bohn
cb
Oooh! What does this button do!?
This isn't Pu-239, the isotope that is used in nuclear weapons. We have huge amounts of Pu-239. Radioisotope Thermoelectric Generators (RTG) use Pu-238, a plutonium isotope with a much shorter half-life (87.7 years). The problem is producing the material. Pu-238 was produced by the Department of Energy as a byproduct of the nuclear weapons materials production infrastructure, which has largely been shut down. There has been discussion of restarting a capability to produce Pu-238, but I'm not sure if any progress has been made. There are plenty of anti-nuclear know-nothings who are opposed to the idea.
Mea navis aericumbens anguillis abundat
Pluto/Kuiper Express (PKE) was to be one of three JPL solar system exploration missions. The other two include Europa Orbiter (intended to determine the existance of a subsurface ocean), and Solar Probe (intended to determine the origin of the solar wind). PKE's purpose was to image Pluto and Charon (Pluto's moon) and a Kuiper Belt object. EO's biggest challenge is it's complex orbit insertion. SP, of course, has to deal with an intense thermal environment.
PKE's principle challenge was to reliably conduct an autonomous encounter navigation after spending 8 years travelling out there. The craft would be zipping past Pluto at a good clip, and clicking a few pictures (for later transfer back to earth) would be tricky - gotta have the camera pointed in just the right directions at just the right time.
The reason autonomy is necessary, is that at Pluto, the round-trip time for a beam of light to travel between Pluto and ground control is 8 hours, but the entire Pluto encounter only lasts a few hours.
Another problem, mentioned in the article, is that finding a launch vehicle with sufficient performance to get enough mass (a few hundred kg's) going on an accurate trajectory, is pretty tricky.
I think it'd be a pretty cool mission, although I can understand why NASA may prefer to direct their funds towards other projects that would return larger amounts of results for less risk. I hope this doesn't mean Europa Orbiter or Solar Probe are also in danger of cancellation.
Uhhhh... interesting statement, but I have to disagree. When Clyde Tombaugh discovered Pluto on February 18, 1930, he was searching for a ninth planet predicted to exist because of discrepancies between the predicted and actual orbits of Uranus (and Neptune) -- the precise reason that the planet Neptune had been discovered, in fact (here's a detailed story of the whole affair). At the time, no one had any notion that Pluto would be so small: it was predicted to be between two and seven times the mass of Earth, and everyone expected it to be dim -- why else would it be so hard to find?
As it turned out, the most likely cause for Uranus and Neptune's orbital discrepancies is probably observational error, and Pluto just happened to be in the approximate neighborhood being searched. If it were discovered today, we might not call it a "planet" -- it's only the largest (so far) of a number of objects in the Kuiper belt -- but this has been the subject of a lot of controversy, and it's been officially decided to keep calling it a planet.
At the time it was discovered, no one had any notion that things would turn out this way, so it was just considered a planet and named as such. No special considerations or rewards -- just ignorance of the future, as always...
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Politics is about making compromises. Religion isn't. --Michael Horton
That type of statement is the reason NASA's budget has been cut so drasticly over the years, which directly led to the high-profile failures of some of the recent Mars missions. We're not looking for anything in particular; the whole point of a mission such as this one would be pure exploration - we don't really know what to look for, so you have to begin somewhere. It's true that there will never be (in our lifetime, at least) any commercial value from the exploration of Pluto, but does that mean we shouldn't go there? If that kind of test were applied to all matters of exploration and research, we'd still be in the dark ages.
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http://gammatron.weblogger.com
Science shouldn't always have a direct application or use. It's their because once in a while it creates something amazing, that changes everything and affects everyone. You can't always directly apply science to solve a need. Sometimes you don't know a need was there until it has been satisfied.
"People of Earth. Welcome. .. or was it miles?.
Please come to our planet.
We are only 5,913,520,000 mil^H^H kilometers from the sun.
er ummm
Nevermind."