roberts@CMR.NCSL.NIST.GOV (John Roberts) (02/07/91)
>From: jack@cwi.nl (Jack Jansen) >Newsgroups: sci.space >Subject: Manoeuvring using rope and anchor(was: Solar Impact Mission.) >Date: 6 Feb 91 00:02:06 GMT >Would it be technically possible to extend the idea of dipping into >the atmosphere by throwing an anchor out to a planet and swinging >around it? What I'm thinking of is, say, a 10Km Kevlar (or Twaron, >for us Dutch:-) cable with something like an anchor at the end, >have the anchor impact a reasonably sized asteroid (a couple Km >diameter, enough orders of magnitude difference in mass that you >don't accidentally send the asteroid somewhere you don't want it >to be), and release anchor and cable once you're facing the direction >you want to go? >I miss even a feeling for too many numbers (tensile strength required, >tensile strength of available materials, positioning accuracy >needed and attainable, g-forces survivable by the average spacecraft) >to start calculating, but maybe someone else wants to give it a try >(or, probably, tell me why this is a ridiculous idea in the >first place)... >Een volk dat voor tirannen zwicht | Oral: Jack Jansen >zal meer dan lijf en goed verliezen | Internet: jack@cwi.nl >dan dooft het licht | Uucp: hp4nl!cwi.nl!jack Of course you would need great accuracy and a very strong (therefore heavy) cable. I think the cable would also have to be longer. The following table gives the maximum velocity of the incoming spacecraft with respect to the asteroid, as a function of cable length and maximum permitted G-force on the spacecraft. These velocities seem a little on the low side for most applications: Cable length(km) Max G | Max V (m/s) -------------------------------+--------------- 10 1 | 313 10 10 | 990 100 1 | 990 100 10 | 3130 Also note that the jerk (sudden change in acceleration) could be a serious problem. There might be some application for a cable permanently attached to an asteroid, to be used by multiple spacecraft. John Roberts roberts@cmr.ncsl.nist.gov