More Moons Around Pluto? Options

[JRehling]

Press Release Source: NASA


NASA's Hubble Reveals Possible New Moons Around Pluto
Monday October 31, 12:30 pm ET


WASHINGTON, Oct. 31 /PRNewswire/ -- Using NASA's Hubble Space Telescope to view the ninth planet in our solar system, astronomers discovered Pluto may have not one, but three moons.
If confirmed, the discovery of the two new moons could offer insights into the nature and evolution of the Pluto system; Kuiper Belt Objects with satellite systems; and the early Kuiper Belt. The Kuiper Belt is a vast region of icy, rocky bodies beyond Neptune's orbit.

"If, as our new Hubble images indicate, Pluto has not one, but two or three moons, it will become the first body in the Kuiper Belt known to have more than one satellite," said Hal Weaver of the Johns Hopkins Applied Physics Laboratory, Laurel, Md. He is co-leader of the team that made the discovery.

Pluto was discovered in 1930. Charon, Pluto's only confirmed moon, was discovered by ground-based observers in 1978. The planet resides about 3 billion miles from the sun in the heart of the Kuiper Belt.

"Our result suggests other bodies in the Kuiper Belt may have more than one moon. It also means planetary scientists will have to take these new moons into account when modeling the formation of the Pluto system," said Alan Stern of the Southwest Research Institute, Boulder, Colo. Stern was co-leader of the research team.

The candidate moons, provisionally designated S/2005 P1 and S/2005 P2, were observed approximately 27,000 miles away from Pluto. The objects are roughly two to three times as far from Pluto as Charon.

The team plans to make follow-up Hubble observations in February to confirm the newly discovered objects are truly Pluto's moons. Only after confirmation will the International Astronomical Union consider names for S/2005 P1 and S/2005 P2.

The Hubble's Advanced Camera for Surveys observed the two new candidate moons on May 15, 2005. The candidates are roughly 5,000 times fainter than Pluto. Three days later, Hubble looked at Pluto again. The two objects were still there and appeared to be moving in orbit around Pluto.

The team looked long and hard for other potential moons around Pluto. "These Hubble images represent the most sensitive search yet for objects around Pluto," said team member Andrew Steffl of the Southwest Research Institute. "It is unlikely that there are any other moons larger than about 10 miles across in the Pluto system," he said.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute in Baltimore conducts Hubble science operations. The Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington.


For detailed information and images about this research on the Web, visit:

http://hubblesite.org/news/2005/19

For information about NASA and agency programs on the Web, visit:

http://www.nasa.gov/home




--------------------------------------------------------------------------------
Source: NASA

[alan]

Unique orbits cannot be calculated from the available
data, but the measured positions are consistent with nearly circular orbits
in the orbital plane of Pluto I (Charon). On this assumption, preliminary
orbital solutions yield a = 64700 +/- 850 km and P = 38.2 +/- 0.8 days for
S/2005 P 1, and a = 49400 +/- and P = 25.5 +/- 0.5 days for S/2005

New moons in resonance with Plutos rotation?
Charon's period is 6.387 days: 6.387 * 4 = 25.6 days ; 6.387 * 6 = 38.3 days

[tasp]

New moons in resonance with Plutos rotation?
Charon's period is 6.387 days: 6.387 * 4 = 25.6 days ; 6.387 * 6 = 38.3 days

If correct, all the satellites of Pluto will essentially repeat their relative positions every 77 days or so. This will limit the number of satellite configurations for the mission designers to evaluate. There won't be any point in moving the arrival date beyond a couple of orbits of the outer satellite. The NH craft will have the same views of all the objects.

[JRehling]

If correct, all the satellites of Pluto will essentially repeat their relative positions every 77 days or so.  This will limit the number of satellite configurations for the mission designers to evaluate.  There won't be any point in moving the arrival date beyond a couple of orbits of the outer satellite.  The NH craft will have the same views of all the objects.

Well, it would allow for 24 distinct configurations of the outer satellites, or whatever fraction of those 24 the "arrival window" allows for -- that seems like a considerable variety of options.

[tasp]

Well, it would allow for 24 distinct configurations of the outer satellites, or whatever fraction of those 24 the "arrival window" allows for -- that seems like a considerable variety of options.

Like in the Jupiter system, due to the resonance of Io, Europa, and Ganymede, certain configurations of the satellites never occur. Like all three in a straight line on the same side of Jupiter. I was annoyed a little when the mission designers of Voyager II's Uranus flyby stated a particularly appealing configuration of the Uranian moons occured just a few days prior to the earliest possible flyby date that preserved the Neptune option. Hence the fuzzy picture of Umbriel.

Should be easier for the analysts to examine ~77 days of moon configurations than potentially years worth.

[tty]

Like in the Jupiter system, due to the resonance of Io, Europa, and Ganymede, certain configurations of the satellites never occur.  Like all three in a straight line on the same side of Jupiter.

Hmm... I didn't know that and so apparently didn't Robert Heinlein. The big quake in "Farmer in the sky" happened when all 4 galileans lined up.

tty

[Rob Pinnegar]

Hmm... I didn't know that and so apparently didn't Robert Heinlein. The big quake in "Farmer in the sky" happened when all 4 galileans lined up.

Callisto can line up with two of the other three, but the last one will always be out of place.

[JRehling]

Callisto can line up with two of the other three, but the last one will always be out of place.

I don't know the details of the Heinlein story, but of course the Galileans can also all line up... but with one of them on the other side of Jupiter. We can also presume that the Galileans were capable of aligning on the same side of Jupiter in the past, before the synchrony was established. Finally, it is possible for all four Galileans to be within 180 degrees of each other, and have it be that from Earth they would appear to be on the same side of Jupiter.