Pluto's moons, possible rings may be hazards to New Horizons spacecraft

October 16, 2012, Southwest Research Institute
New Horizons Spacecraft as it approaches Pluto

NASA's New Horizons spacecraft is now almost seven years into its 9.5-year journey across the solar system to explore Pluto and its system of moons. Just over two years from now, in January 2015, New Horizons will begin encounter operations, which will culminate in a close approach to Pluto on July 14, 2015, and the first-ever exploration of a planet in the Kuiper Belt.

As New Horizons has traveled through the solar system, its science team has become increasingly aware of the possibility that dangerous may be orbiting in the Pluto system, putting 's and its exploration objectives into harm's way.

"We've found more and more moons orbiting near Pluto—the count is now up to five," says Dr. Alan Stern, principal investigator of the New Horizons mission and an associate vice president of the Space Science and Engineering Division at Southwest Research Institute. "And we've come to appreciate that those moons, as well as those not yet discovered, act as debris generators populating the Pluto system with shards from collisions between those moons and small ."

"Because our spacecraft is traveling so fast—more than 30,000 miles per hour—a collision with a single pebble, or even a millimeter-sized grain, could cripple or destroy New Horizons," adds New Horizons Project Scientist Dr. Hal Weaver, of the Johns Hopkins University Laboratory, "so we need to steer clear of any debris zones around Pluto."

The New Horizons team is already using every available tool—from sophisticated computer simulations, of the stability of debris orbiting Pluto, to giant ground-based telescopes, stellar occultation probes of the Pluto system, and even the —to search for debris in orbit. At the same time, the team is plotting alternative, more distant courses through the Pluto system that would preserve most of the but avert deadly collisions if the current plan is found to be too hazardous.

"We're worried that Pluto and its system of moons, the object of our scientific affection, may actually be a bit of a black widow," says Stern.

"We're making plans to stay beyond her lair if we have to," adds Deputy Project Scientist Dr. Leslie Young of Southwest Research Institute. "From what we have determined, we can still accomplish our main objectives if we have to fly a 'bail-out trajectory' to a safer distance from Pluto. Although we'd prefer to go closer, going farther from Pluto is certainly preferable to running through a dangerous gauntlet of debris, and possibly even rings, that may orbit close to Pluto among its complex system of moons."

Stern concludes: "We may not know whether to fire our engines on New Horizons and bail out to safer distances until just 10 days before reaching Pluto, so this may be a bit of a cliff-hanger. Stay tuned."

Explore further: New Horizons becomes closest spacecraft to approach Pluto

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2.9 / 5 (8) Oct 16, 2012
This is why dual probes are such a good idea. We did it for Pioneer and Voyager (not to mention Viking on Mars). A close fly-by would be a far easier call if we knew we had a second spacecraft following.
3.1 / 5 (9) Oct 16, 2012
Yea, or a cluster. I would think we can produce micro probes now that would locally communicate with a larger probe that stays a safe distance from the target while in turn talks with earth. So when your a few weeks away, launch a dozen micro probes or so all taking pictures from different positions. You'll get redundancy, more pictures from all sides of the target, and some great stereoscopic details.
2.7 / 5 (3) Oct 16, 2012
Yea, or a cluster.

And how would you keep this cluster from scattering everywhere and flying in formation? Strings? Rubber bands? If you install micro-jets on each of them then this will ad extra weight which translates to extra cost. If you need a single larger unit to coordinate the swarm it's simpler and cheaper to just send said unit alone. And we all know NASA is on tight budget.
3 / 5 (1) Oct 17, 2012
Allex, by having a look at transfer orbits, it seems to me that you can have these probes on the same trajectory almost all the way. Since you have to perform delta v maneuvers prior to getting in orbit around the desired objects (supposing getting in orbit is the goal), then you simply must perform slight delta-v differences in order for the probes to be in slightly different orbits.

"Engineeringly" speaking, it's not a hugely difficult feat.
3 / 5 (2) Oct 17, 2012
Yea, or a cluster.

If you install micro-jets on each of them then this will ad extra weight which translates to extra cost.

The redundancy would make it possible to cut costs in other areas, such as using off-the-shelf CPUs and sensors with moderate shielding instead of their radiation-hardened counterparts costing 1,000 times more. If the failure rate is higher than anticipated, it merely degrades the quality of the mission. With a single probe, if the failure rate is higher than expected, it's often a total waste of hundreds of millions of dollars.
5 / 5 (1) Oct 17, 2012
I really hope all goes well. Will New Horizons provide us with decent images of Pluto?

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