Pluto Kuiper Express' major science objectives were to:
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The overall structure of the spacecraft was to be an aluminum hexagonal bus with no deployable structures. Of the total 220 kg mass of the spacecraft, only about 7 kg would have consisted of science instruments. Power would have been provided by radioisotope thermal generators (RTGs) similar in design to those used on earlier missions (e.g., Galileo or Cassini). It was planned to use spare RTGs from Cassini. Communications would have been via a fixed, 1.47 m high-gain antenna employing an X-band uplink receiver and downlink transponder. Pointing control would have been maintained by a wide-field star tracker and a set of three solid-state rate sensors. The on-board computer was to have been a 1.5 MIPS RISC-based system capable of processing a science data stream of 5 Mbps. The solid-state data storage system was to be capable of storing 400 Mb in both compressed and uncompressed formats. Data storage capacity and transmission rates would allow the transmission of 1+ gigabit of science data over a one year period. Planned experiments for the spacecraft included a multi-color visible light imaging system, an infrared mapping spectrometer, an ultraviolet airglow and solar occultation spectrometer, and a radio occultation experiment utilizing an ultrastable oscillator (USO) and the on-board telecommunications system.
There was originally a study of a potential cooperative effort with Russia involving the inclusion of Zond probes, to study the Plutonian atmosphere. Strawman experiments for the probe included either a mass spectrometer or a retarding potential analyzer, an atmospheric imager, and an accelerometer. The Zond would separate from the flyby spacecraft about 30 days prior to closest approach and relay data prior to impact on Pluto. This possibility no longer looks feasible.
Launch of the Pluto Kuiper Express spacecraft was to be on either a Delta rocket or from the Space Shuttle, tentavely scheduled for December 2004. It was planned for the spacecraft to obtain a gravity assist from Jupiter in April to June 2006 to obtain sufficient velocity to fly by Pluto in December 2012. To accomplish the mission goal of 1 km resolution mapping, the closest approach distance would be about 15,000 km. The flyby velocity would be 17-18 km/s. The infrared spectrometer required a spatial resolution of 5-10 kilometers per pixel. Studies of Pluto's neutral atmosphere would determine the mole fractions of nitrogen, carbon monoxide, methane and other gases to at least the one percent level. Data would be transmitted back to Earth for a year following the flyby. After the flyby the spacecraft would continue on to the Kuiper Belt where it will use the imaging camera to search for Kuiper Belt objects. If good flyby candidates are found trajectory maneuvers can be made to allow close approach and study of the object.
Spacecraft and Subsystems
Mission Profile
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