That's why the NASA study (HERTS) suggested using an electrostatic solar sail. It's only consumables are the noble gas and/or metal plating of the hollow cathode electron emitters used to keep the craft positively charged.
Actual station keeping +- a few meters once out on the gravitational focal line opposite the target system (which itself is moving) would require some cold gas thrusters that would limit the duration of the mission. But the forces and accelerations required are very small when you're 600 AU out from the sun and even the photon pressure isn't throwing things off anymore.
Yes, getting out there with enough mass for station keeping would be hard and it'd require new methods. Either electrostatic solar sails, or a more traditional H-reversal oberth burn close to the sun.
Actual station keeping +- a few meters once out on the gravitational focal line opposite the target system (which itself is moving) would require some cold gas thrusters that would limit the duration of the mission. But the forces and accelerations required are very small when you're 600 AU out from the sun and even the photon pressure isn't throwing things off anymore.
Yes, getting out there with enough mass for station keeping would be hard and it'd require new methods. Either electrostatic solar sails, or a more traditional H-reversal oberth burn close to the sun.