REM@IMSSS (Robert Elton Maas, this host known locally only) (02/07/86)
R> When ... ion rocket developed so we can send ... spacecraft (orbiter/lander) R> to all the outer planets without having to wait ten years to get the R> craft to the very outer ones via gravity-assist from the nearer ones? D> Date: 28 Jan 86 00:52:14 GMT D> From: allegra!princeton!astrovax!escher!doug@ucbvax.berkeley.edu D> The major problem with running ion driven spacecraft to the D> outer planets is their strong magnetic fields. ... The other problem is D> restarting the drives. They tend to foul up when they are D> shut down, so you only get one sure shot per engine. Thanks for the good info. It sounds like lots of progress has been made as well as general mostly-unsolvable problems discovered, so we know where we stand and can intelligently plan an actual mission. D> Is it time to push for this for the next wave of planetary D> exploration? Mariner Mark II doesn't have any ion rockets, ... Yes I think so. I really don't like the all eggs in one basket approach when it takes ten years to find out if the basket worked and try again if it didn't. If we could get relatively instant transportation to Jupiter or Neptune etc. for our probes we could learn whether it worked or not and send either a better one if it did or a copy if it failed, then we wouldn't have to make such perfect spacecraft, we could tolerate occasional failure more gracefully, not to mention getting more info in my lifetime. Also we need to send spacecraft with telescopes out a significant fraction of a lightyear to get a giant baseline for triangulation to measure distances to things. Wouldn't it be just dandy if we could get a baseline large enough and telescopes unpurturbed by Earth's atmosphere so we could measure the distance to M31 directly by triangulation and compare that with what we get from observing Cephids so as to get a direct measure of absorbtion from here to there? Also with craft out very far we are out of the purturbations of the giant planets and can measure far fainter purturbations caused by clumping in the postulated Oort cloud or the postulated Nemesis dark star or anything else out there; By measuring the distance to the Earth by laser ranging to an accuracy of a few centimeters and over time observing deviations of the craft's trajectory from that we compute from Sun and known planets, giving incredibly accurate measurement of purturbations along that axis. By having two or more craft out in different directions, and using laser ranging from craft to craft, we get incredibly accurage measurement along other axis, thus combine them to get 3-dimensional purturbation measurements. Yeah, I say let's push "them" to get moving on deep space ion-rocket missions, and have them do it or tell us why it can't be done. Disclamer: I'm not perfect, but if I had a big staff and circulation of thousands I wouldn't make such blunders as Leonard Koppett made the other day, referring several times to the 'Viking 2' which passed by Uranus this week.