New Horizons May Enter a Firing Range at Pluto
Pluto's moons and possible rings may be hazards: New Horizons and the Gauntlet it may encounter in 2005
As New Horizons has traveled through the Solar System, its science team has become increasingly aware of the possibility that dangerous debris may be orbiting in the Pluto system, putting NASA's New Horizons spacecraft 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, and those not yet discovered there, act as debris generators that populate the Pluto system with shards from small, colliding Kuiper Belt objects."
"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 Applied Physics 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 Hubble Space Telescope -- 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 science mission but avert deadly collisions if the current flyby plan is found to be too hazardous.
"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."