2014 MU69 "Ultima Thule" flyby, For discussion of the encounter as it happens Options

[elakdawalla]

It's only 10 days now until the "Core" phase of the 2014 MU69 flyby begins! I thought it was time for a new thread. Carry on discussing distant observations of other KBO worlds in the KBO encounters thread, and use this one for MU69 until after the departure phase is officially over on 8 January.

I'll be posting a "What to Expect" article next week.

[Floyd]

They will use LORRI to look for targets.

They will use LORRI to examine known objects and get light curves and other information.

To find new potential objects to visit next will require getting an extension of the mission approved and getting time on Hubble and terrestrial big scopes to search for objects that they can reach. They will then need to determine the new objects orbit precisely with star occultations---ie a repeat of how they found 214 MU69 and got its orbit.

[Therion]

Actually, according to Alan Stern's post in "KBO encounters" thread, they will use LORRI to search for another targets : )

Owing to our remaining expected fuel supply we will have to search for small targets, which are more numerous. Calcs show this is most likely to be a flyby of a pristine comet nucleus. Such objects are about V=35 from Earth: hence undetectable, even with HST.

So we would have to detect it with LORRI on New Horizons itself, which can see 3-10 km targets up to about 6 months ahead of us. Feasibility calcs will be done in 2019 (preliminary calcs are pessimistic but we really haven't scoured this to a solid conclusion). We'll see if this can work-- I hope so. It would be very cool to detect and target all from New Horizons with a "target of opportunity" flyby sometime n the 2020s!

[HSchirmer]

Actually, according to Alan Stern's post in "KBO encounters" thread, they will use LORRI to search for another target: )

Yes, at this point in time, our best "eye on the Kuiper belt" is on the spacecraft IN the Kuiper belt;
in an odd way, it's interesting, frustrating, and exciting; all at the same time.

The /possibility/ versus practicality of NH finding its own targets has been the focus of a bit of discussion over the years: speculation kicks up every few years, as necessity prods invention.

As of 2012, HST was a better telescope...

http://www.unmannedspaceflight.com/index.p...st&p=189526
Aug 23 2012, 05:13 AM

Right, our camera aperture is small enough that even though we're closer to the KBOs there's no advantage to searching from the spacecraft. Plus our maximum exposure time is 10 seconds compared to the hours we can integrate from the ground, and it takes thruster fuel to hold the spacecraft steady during those 10 second exposures, so we can't take too many of them. Oh, and because of the need to use thrusters to hold the spacecraft steady, our best spatial resolution for those long exposures is about 4 arcseconds, compared to the ~0.6 arcseconds we can get from the Earth (on a good night). The lower spatial resolution makes it difficult to distinguish and KBOs from all the background stars.

New Horizons would have a sensitivity advantage for KBOs that are very small and close to the spacecraft, as algorimancer says, but we don't think there are many of those, and we don't have the onboard smarts to find them autonomously in the images onboard the spacecraft, and we don't have the bandwidth to send enough of them back to Earth for processing even if we could afford the fuel for all those long exposures...

So we'll just have to keep searching with the big telescopes here on Earth.

John

Now, as of 2019 LORRI is functionally better than HST, so you just use the best scope you've got,
at least until JamesWebb is up and running....