KBO encounters Options

[john_s]

One unique thing that New Horizons can do even for quite distant KBOs is measure their phase curves- KBO observations from Earth are always restricted to phase angles less than a degree or two, but New Horizons can get much higher phase angles, sometimes up to 90 degrees or above, for several bright KBOs. That gives us information on their surface textures that we just can't get from Earth.

John

[hendric]

Pluto is currently going through the center of the Milky Way, as seen from Earth

https://www.fourmilab.ch/cgi-bin/uncgi/Yourtel?aim=9&z=1

http://earthsky.org/tonight/milky-way-broa...in-southern-sky

[fredk]

But KBO's will be distributed all around the ecliptic, so most will be far from the Galactic plane as viewed from earth. It is true that those KBO's near Pluto's ecliptic longitude will be viewed against the Milky Way from earth and will tend to appear farther from the Galactic plane from the point of view of NH. But the big majority of KBO's will be viewed against a dark sky from earth.

[pitcapuozzo]

According to Alan Stern, today marks New Horizons' first of four maneouvres to intercept 2014 MU69. The engine burns will be distributed over 2 weeks for a total delta v of 57 meteres per second.

[bkellysky]

Pluto is currently going through the center of the Milky Way, as seen from Earth

I've had lots of fun at our star parties (our 'Starway to Heaven') pointing out Pluto is near the 'teaspoon' above Sagittarius' 'teapot'. We can't see Pluto, much less New Horizons, but it's fun to have a handy grouping of stars to show its location.

[abalone]

NASA's New Horizons spacecraft has carried out the first in a series of four initial targeting maneuvers designed to send it toward 2014 MU69 - a small Kuiper Belt object about a billion miles beyond Pluto, which the spacecraft historically explored in July.

The maneuver, which started at approximately 1:50 p.m. EDT on Oct. 22, used two of the spacecraft's small hydrazine-fueled thrusters, lasted approximately 16 minutes and changed the spacecraft's trajectory by about 10 meters per second.
The remaining three KBO targeting maneuvers are scheduled for Oct. 25, Oct. 28 and Nov. 4.
http://www.spacedaily.com/reports/Maneuver...Target_999.html

[Explorer1]

Third maneuver completed; largest burn of the mission at 30 minutes! http://pluto.jhuapl.edu/News-Center/News-A...p?page=20151029

[tfisher]

I think the New Horizons KBO search field overlaps the Planet Nine hypothesized region where it crosses the galactic plane near perihelion. Any idea if the KBO search was sensitive to objects that slow-moving? (See http://www.findplanetnine.com/p/blog-page.html for Planet Nine hypothesized regions.)

[elakdawalla]

An amusing story from today's SBAG meeting: Alan has twice contacted Jim Green at NASA about NASA running a naming contest for MU69, but NASA has not yet gotten the ball rolling. So now, Alan says, the New Horizons team is referring to the KBO target internally as "Jimgreen."

[HSchirmer]

the New Horizons team is referring to the KBO target internally as "Jimgreen."

Shouldn't that be latinized to "Iacomus verde" or mythologized to "Bredbeddle"?

[charborob]

Or rather "Iacobus viridis".

[Explorer1]

More info about the KBO encounter in the new PI Perspective:

http://pluto.jhuapl.edu/News-Center/PI-Per...tive_04_14_2016

[jasedm]

Thanks for the link Explorer1

This will be (probably) humankind's only visit to MU69, and that makes the flyby achingly special....

But I'm a little bewildered.

I recall that when the imaging sequences for the Pluto/Charon flyby were designed, the constraints in our knowledge of Pluto's precise position necessitated a 'best-guess' for instrument pointing during the flyby. There was an uncertainty ellipsoid and the camera sequences were designed with the possibility that a number of LORRI frames may be just of empty space. This during a flyby at a range of 12,500km from a 2,370km diameter target, following orbit determination using some of the best assets available for the best part of a century. (i.e the world's best telescopes and generations of very talented scientists)

How then are the team able to confidently predict 25m/pixel images on a body that has only been known to us for two years, is 60 times smaller, and from a range four times closer?

Note: the team have shown themselves to be amazingly proficient at gathering science at Pluto, so I don't doubt their abilities, but how will the viewing geometry be predictable to that degree?

Am I missing something?

[Explorer1]

Wouldn't they do what the Cassini team did for those tiny shepherd moon flybys (Pandora, Pan, Atlas, Methone, etc) where they just cover as much of the sky where they predict it will be as possible? Even if lots of pictures are empty space, they will catch it easy enough during CA, when it fills more sky. And of course (once official approval is given) it will be easy to make distant observations during the approach to refine it's position. Already lots of practice at Pluto's small moons, the Jupiter system, and even that 2006 asteroid flyby...

[stevesliva]

The pointing is simpler, I think. NH will point towards the sunlit hemisphere until it's looking at empty space rather than the KBO. And then it turns around and looks back at it. Since the final pointing brackets when the spacecraft passes the KBO, it will eventually fill a frame, even if which frame isn't known.

At Pluto, the pointing turned to look at the sub-spacecraft hemisphere, and towards the moons... knowing where that was was difficult. And it would be really difficult for the the KBO, too, if they were trying to slew to look at the surface as NH passes. But judging by the blurry powerpoint slide, they're not. They just stare straight ahead, and then straight back. More or less.