Stern, the New Horizons mission lead, says the odds of finding yet another target are “small, but not zero.” That isn’t stopping scientists from searching. “We’re working on that right now,” Stern says. And they’ve turned to the Hubble Space Telescope once again.New Horizons co-investigator Simon Porter, also from SwRI, says that the search that turned up 2014 MU69 only looked for cold classical Kuiper Belt objects, which have distinct orbital characteristics. He’s now expanding the search to include other worlds, which expands the potential targets. Porter says he hopes to find something called a scattered disk object. These worlds are remnants of the original Kuiper Belt that Neptune’s massive gravity flung all across the outer solar system. No one’s ever seen a scattered disk object up close.[...]Either way, this time it shouldn’t take a decade to find out if New Horizons has one more flyby left. “I actually hope to know by mid-year if there’s anything in that (Hubble Space Telescope) data,” Stern says.
Green Beacon JUST received from @NewHorizons for this week! Next Monday we wake her up from hibernation for some SCIENCE! #PlutoFlyby
AlanStern @AlanSternReplying to @RealAntonioM and @NASA05:33 UT on 1 Jan 2019
That milestone will mark the farthest planetary encounter in history ...
Quote from: Star One on 09/06/2017 06:58 pmThat milestone will mark the farthest planetary encounter in history ...Planetary encounter? I'm not sure a flyby of a smallish KBO qualifies as a planetary encounter! (Not even if they say it twice. )
Quote from: CuddlyRocket on 09/08/2017 10:43 pmQuote from: Star One on 09/06/2017 06:58 pmThat milestone will mark the farthest planetary encounter in history ...Planetary encounter? I'm not sure a flyby of a smallish KBO qualifies as a planetary encounter! (Not even if they say it twice. )Alan Stern thinks everything is a planet, even our Moon.https://phys.org/news/2017-02-geophysical-planet-definition.html
New software will be uploaded to the probe’s computers in October in preparation for the MU69 flyby while the mission operations and science teams will plan the details of the probe’s trajectory. A course correction maneuver aimed at setting the exact flyby time will be conducted on Dec. 9, 2017.
One particular finding – a lack of variation in MU69’s brightness as it rotates – could result in New Horizons not needing to adjust its path during the flyby, resulting in less fuel being used. Stern said the lack of brightness variation either means the object is not presenting vastly different cross-sections to us as it rotates, or telescopes are looking down the barrel of the rotation axis.“It doesn’t matter where in the rotation phase we show up,” Stern said. “We are going to see about the same amount of terrain.”
Fuel saved during the MU69 encounter could be used to send New Horizons to a third KBO, a move that would require yet another mission extension. In 2016, NASA approved an extended mission for the MU69 flyby through the year 2021.On Sept. 6, Stern told members of NASA’s Outer Planets Assessment Group that mission scientists are already searching for an additional KBO target.“We have a fighting chance of having a second [Kuiper Belt Object] flyby,” Stern said.Approval of another mission extension will also provide more opportunities for New Horizons to continue its distant observations of KBOs, dwarf planets, and centaurs. Stern said he expects to request a second extension once the MU69 flyby is completed and the data collected from it returned to Earth.Even that might not be the mission’s end. Stern foresees additional extensions beyond the one that would take it to a second KBO.“There’s fuel and power on board the spacecraft to operate it for another 20 years,” Stern said. “That’s not going to be a concern even for a third or fourth extended mission.”The probe will be put into another hibernation on Dec. 22, 2017, where it will remain until June 4, 2018, when it will be woken up in preparation for the MU69 encounter, which will officially begin in August 2018.
We searched for dust or debris rings in the Pluto-Charon system before, during, and after the New Horizons encounter. Methodologies included searching for back-scattered light during the approach to Pluto (phase ∼15∘), in situ detection of impacting particles, a search for stellar occultations near the time of closest approach, and by forward-scattered light during departure (phase ∼165∘). A search using HST prior to the encounter also contributed to the results. No rings, debris, or dust features were observed, but our detection limits provide an improved picture of the environment throughout the Pluto-Charon system. Searches for rings in back-scattered light covered 35,000-250,000 km from the system barycenter, a zone that starts interior to the orbit of Styx, and extends to four times the orbital radius of Hydra. We obtained our firmest limits using the NH LORRI camera in the inner half of this region. Our limits on the normal I/F of an unseen ring depends on the radial scale of the rings: 2×10−8 (3σ) for 1500 km wide rings, 1×10−8 for 6000 km rings, and 7×10−9 for 12,000 km rings. Beyond ∼100,000 km from Pluto, HST observations limit normal I/F to ∼8×10−8. Searches for dust from forward-scattered light extended from the surface of Pluto to the Pluto-Charon Hill sphere (rHill=6.4×106 km). No evidence for rings or dust was detected to normal I/F limits of ∼8.9×10−7 on ∼104 km scales. Four occulation observations also probed the space interior to Hydra, but again no dust or debris was detected. Elsewhere in the solar system, small moons commonly share their orbits with faint dust rings. Our results suggest that small grains are quickly lost from the system due to solar radiation pressure, whereas larger particles are unstable due to perturbations by the known moons.