Starship Asterisk*

MarkBour wrote:
As to that question of slowing down on arrival, I know there's one way to do it, and that's to smash into the planet. More seriously, though, NASA long ago became adept at making great use of gravity assists. Is there a corresponding way to obtain a "gravity hindrance"? Not that it would initially seem a useful thing, but surely the NH probe could have left Jupiter travelling slower, rather than faster, correct? Of course that's not what we wanted. But suppose we wanted to fly a probe into the Saturn system very fast and to decelerate more than our fuel alone could accomplish. Could careful targeting and selective burns have it swing around several moons and use them as a sequence of brakes? At first guess, though, it seems that if you can't use a given body's gravity to capture the probe in the first place, it is probably very limited how much you can steer around it and get any slow down.

• If one throws a ball in the air at 32 ft/s
  it will come to a stop 16 ft up (after one second)
  for an average speed of 16 ft/s ( = 32/2).

DavidLeodis wrote:The success of the mission is a great achievement.

In the information brought up through the 'survived its close encounter with Pluto' link I was surprised to read "New Horizons is collecting so much data it will take 16 months to send it all back to Earth"

neufer wrote:

Chris Peterson wrote:

neufer wrote:
Escape velocity at Jupiter's orbit is still ~11.5 mps

Meters per second?

Solar escape velocity at Jupiter's orbit (5.2 AU) is 18.5 kilometers per second.

"Pianosorplanets" was clearly using mps (= MPS = miles per second) so I was responding in kind.

Sorry for the confusion.

Chris Peterson wrote:

neufer wrote:
Escape velocity at Jupiter's orbit is still ~11.5 mps

Meters per second?

Solar escape velocity at Jupiter's orbit (5.2 AU) is 18.5 kilometers per second.

neufer wrote:Escape velocity at Jupiter's orbit is still ~11.5 mps

Pianosorplanets wrote:
When NH passed Jupiter it accelerated to 14.2mps. When it left Earth, I believe the speed worked out to about 10.1mps. When it reached Pluto, we're getting quoted around 10mps again. So some retrorockets must have fired around here someplace?... Space dust doesn't slow your speed down that much over that short a distance. If they could drop 14,000 mph as a part of this mission, I find it hard to believe that it would have been THAT expensive to drop more. The thing only is the size of a Grand Piano and weighs a lot less. I rebuild grand pianos for a living and can pick up the corner of a concert grand by myself...

Pianosorplanets wrote:

richardschumacher wrote:

Guest wrote:What is the remaining purpose of the the mission? Why didn't they put it into orbit and gather tons o' data?

It's about the best we can do with available technology and money. It takes energy to speed up and slow down a spacecraft. Moving fast enough to get to Pluto in reasonable time, New Horizons couldn't carry nearly enough rocket fuel to slow down again and enter orbit.

I know that's been the word on the street for some time. But I'm wondering about it all. When NH passed Jupiter it accelerated to 14.2mps. When it left Earth, I believe the speed worked out to about 10.1mps. When it reached Pluto, we're getting quoted around 10mps again. So some retrorockets must have fired around here someplace?... Space dust doesn't slow your speed down that much over that short a distance. If they could drop 14,000 mph as a part of this mission, I find it hard to believe that it would have been THAT expensive to drop more. The thing only is the size of a Grand Piano and weighs a lot less. I rebuild grand pianos for a living and can pick up the corner of a concert grand by myself...

Pianosorplanets wrote:I know that's been the word on the street for some time. But I'm wondering about it all. When NH passed Jupiter it accelerated to 14.2mps. When it left Earth, I believe the speed worked out to about 10.1mps. When it reached Pluto, we're getting quoted around 10mps again. So some retrorockets must have fired around here someplace?... Space dust doesn't slow your speed down that much over that short a distance. If they could drop 14,000 mph as a part of this mission, I find it hard to believe that it would have been THAT expensive to drop more. The thing only is the size of a Grand Piano and weighs a lot less. I rebuild grand pianos for a living and can pick up the corner of a concert grand by myself...

Prospero wrote:

Guest wrote:What is the remaining purpose of the the mission?

I hope I have remembered the gist, not garbled it too much, because I cant find the page again

EDIT2
BBC Radio4 just done a piece on NH and said 2 poss. objects, flyby not till 2020.

richardschumacher wrote:

Guest wrote:What is the remaining purpose of the the mission? Why didn't they put it into orbit and gather tons o' data?

It's about the best we can do with available technology and money. It takes energy to speed up and slow down a spacecraft. Moving fast enough to get to Pluto in reasonable time, New Horizons couldn't carry nearly enough rocket fuel to slow down again and enter orbit.

dushyant wrote:Is it really a surprise that the surfaces have relatively few craters ? Its a system whose center of gravity is outside Pluto's surface. Therefore, an incoming one will just fly through, as meteors are incredibly fast. There is a good chance that the meteor will never return back to the Pluto system. Very few that did come back formed a crater eventually.

dushyant wrote:Is it really a surprise that the surfaces have relatively few craters ? Its a system whose center of gravity is outside Pluto's surface. Therefore, an incoming one will just fly through, as meteors are incredibly fast. There is a good chance that the meteor will never return back to the Pluto system. Very few that did come back formed a crater eventually.

montylc2001 wrote:Ok, I know this may be a stretch........but studying the north pole of Charon, the dark area seems to be actually a depression, not a plain, surrounded by shallow angled cliffs. Almost like a golf divot. Initial shape of Hydra would seem to fit in it like a piece from a jigsaw puzzle. And Hydra's apparent size would allow it to fit neatly in the gray area..........................................

Nitpicker wrote:I keep seeing references to Pluto's north pole on this illuminated side. I don't believe it is correct to call it the north pole. If Pluto were still considered a planet, the illuminated pole we see here, points comfortably below the ecliptic and invariable plane and so would be the south pole. And if considered a dwarf planet, the illuminated pole becomes the positive pole, via the right-hand rule.

(What a great image! But I'm surprised no one has complained that it is upside down. )

montylc2001 wrote:Closely studying the latest most detailed image of Charon, it looks like a cracked eggshell with the pieces poorly reassembled. Charon impact with Pluto almost shattered it, gravity pulled it back together?