Why did the "target dots" turn out not to be usable for SSRMS navigation? This probably was a significant lesson learned, as it'd have been a good thing for Canadarm2 to be able to confirm its position autonomously, rather than depending on crewmembers with video monitors as a backup to the joint sensors. This would only have applied to relocation tasks with ample clearances; one could imagine the arm making a series of inchworm moves without human involvement, once you can trust the control systems.By the way, is any (non-L2) speeded-up video available of the SSRMS relocating as an inchworm? I would've expected NASA to assemble a series of such moves, for the visual interest.In reading the interesting 62pp of this thread, I found mention of the target dots' purpose, as well as their not being provided on recent modules because they didn't work as planned -- but nothing as to why they failed.NSF is the best! Thanks.
In reading the interesting 62pp of this thread, I found mention of the target dots' purpose, as well as their not being provided on recent modules because they didn't work as planned -- but nothing as to why they failed.NSF is the best! Thanks.
That makes sense; a fixed-sized dot on a white background isn't very distinctive once you add noise and fuzziness. They should've put a distinctive pattern around the periphery of the white circle, so it would stand out under even adverse conditions.
1. Why we do not use each supply ship that is sent as an extra section, so it gets bigger & bigger,2. I would guess, that the larger the size, the great effect on the pull of gravity to earth,could this be overcome, by changing orbit a few miles.
Quote from: parker on 03/22/2009 04:10 pm1. Why we do not use each supply ship that is sent as an extra section, so it gets bigger & bigger,2. I would guess, that the larger the size, the great effect on the pull of gravity to earth,could this be overcome, by changing orbit a few miles.1. No $$$$2. Size* or weight has no effect on the orbit of the ISS. Once an object is in orbit, it will stay in the same orbit* other posters don't muck up the discussion with drag
+ As mass increases, the amount of reboost you can do per unit of available thrust decreases, meaning it gets harder and harder to keep the station at the correct orbit.
During last week's post launch news conference, there was some Q+A about expedition handover, overlap, crew changeout, etc. One of the guys (Gerst or Suffredini) was talking about "direct handover" vs "indirect handover". I didn't quite follow what he was talking about. I think it was in the context of making sure that the expedition crews had a full 7-10 days of overlap in order to do a good transition, without the distraction of also having a shuttle mission docked, but I didn't fully understand the jargon. Can someone explain?
Quote from: ChrisC on 03/22/2009 05:37 pmDuring last week's post launch news conference, there was some Q+A about expedition handover, overlap, crew changeout, etc. One of the guys (Gerst or Suffredini) was talking about "direct handover" vs "indirect handover". I didn't quite follow what he was talking about. I think it was in the context of making sure that the expedition crews had a full 7-10 days of overlap in order to do a good transition, without the distraction of also having a shuttle mission docked, but I didn't fully understand the jargon. Can someone explain?erioladastra is probably the one to answer this, but my understanding is that direct handover means the new Soyuz docks before the old one leaves, allowing the new crewmembers to take the handover directly from the departing crewmembers, while indirect handover means the old Soyuz leaves first, so the handover is performed by the three "holdover" crewmembers. (Obviously only applies with a 6-person crew; an indirect handover with a 3-person crew leaves ISS temporarily uninhabited.)The reason why this might be necessary is shortage of Soyuz/Progress/ATV docking ports. There are currently only three, and a direct handover will require all three (two for the old Soyuzes and one for the new one). That means that the Soyuz rotation schedule will be tightly coupled with the Progress/ATV schedule. Indirect handover frees up a port so that the Progress/ATV schedule can be kept independent (to some extent) from the Soyuz schedule.
question on CETA move:Doesn't CETA have (unpowered) Grapple fixture attached? Why use astronaut as end-effector?