gravity tractor?

[fingersfray]

does near work as a gravity tractor if so where is it pulling Eros?

[apodman]

http://antwrp.gsfc.nasa.gov/apod/ap090607.html

does near work as a gravity tractor if so where is it pulling Eros?

A gravity tractor does not make physical contact with the asteroid. NEAR crash landed on Eros and is therefore not a gravity tractor.

... maintaining a stable orbit close to the asteroid would be complicated if the object has a complex shape or a complex rotational behavior, as was the case for the NEAR mission ... that visited 433 Eros.

This quote refers only to NEAR's orbit (prior to crash landing) around Eros. NEAR's orbital stability may be compared with that of a gravity tractor, but it does not mean that NEAR itself was a gravity tractor. While every object has gravity and NEAR therefore affected Eros gravitationally in some minor way, I would guess that NEAR was too small and the time frame was too short for the effect to be anything but minuscule. (The asteroid in the example in the quoted article is only 1/7,000,000 of the mass of Eros, and the gravity tractor in the example orbits for 10 years.)

---

Note to bystander et al. - this Gravity Tractor is used for a long strange trip.

[fingersfray]

good call, remember the landing well, but surely the impact it's self would have displaced Eros a small amount? and while in orbit the gravitational effects should have been noticeable no matter how small. ??? was this not a perfect time to test an as yet untested theory, info if possible. sorry for the low brow form of question. but am just an interested star child. near was a triumph of human ingenuity and could have surely been a form of proving the less dramatic ways of near earth asteroid manipulation. i refer to the treaty banning the use of nuclear weapons in space?

[ta152h0]

Of all the images I vote this one to be the most intriguing

http://near.jhuapl.edu/iod/20000503/index.html

Amazing surface obviously incessantly pounded and filled with ancient dirt except for one lone shiny rock. If I hadn't seen 2001 A Space odyssey I would have looked at this differently. Or maybe not without proof.

[apodman]

surely the impact it's self would have displaced Eros a small amount? and while in orbit the gravitational effects should have been noticeable no matter how small. ???

Eros has a mass of nearly 7,000,000,000,000,000 kg. While I can't find the mass for NEAR, it is probably less than 1,000 kg which would make the mass ratio more than 7,000,000,000,000 to 1. You would need quite a sensitive instrument to detect the gravitational perturbation caused by NEAR in orbit with a ratio like that (the wobble of Eros on its center caused by the orbiting NEAR would be small, and the perturbation of Eros' orbit around the sun would be many orders of magnitude smaller yet). The impact might produce a measurable effect (with its position measured one or many more orbits around the sun later) if you slammed NEAR into Eros at a very high speed, but in this case it was a fairly soft - 8 km/h is walking speed - crash landing (unlike the higher velocity Deep Impact probe and its target comet).

Don't get me wrong. I'm all in favor of ingenuity including gravity tractors for deflecting dangerous asteroids, and I'm all in favor of NEAR and its mission. I just think that NEAR's mission was a good step in the research process that wasn't intended to produce all the results you are asking to attribute to it. In a later mission I'm sure we will try more massive spacecraft with more provocative orbits or faster impacts.

[fingersfray]

ah all eyes on deep impact, thanks for the high brow replies, just asking the questions here, and have been impressed by the response so quickly love to think that you boffins are on top of things. count down to deep impact t minus ? days, weeks, years.

[BMAONE23]

Of all the images I vote this one to be the most intriguing

http://near.jhuapl.edu/iod/20000503/index.html

Amazing surface obviously incessantly pounded and filled with ancient dirt except for one lone shiny rock. If I hadn't seen 2001 A Space odyssey I would have looked at this differently. Or maybe not without proof.

Interesting image link

that thing casting a shadow in the upper right crater almost resembles a piece of mining equipment.

[rstevenson]

that thing casting a shadow in the upper right crater almost resembles a piece of mining equipment.

It's one of these, I'm pretty sure.
http://outdoors.webshots.com/photo/2002 ... 4617qRtlWh

Rob

[ta152h0]

I would say a " chromed one of these ". I didn't see any scratches or rolling down the crater marks. It just sits there and in striking contrast to the entire surface around it. We must return , pass the beer please.

[BMAONE23]

I was thinking more along the lines of a 75' surface mining tower with a conveyor going below the surface