Pluto Kuiper Express

Description

This mission has been cancelled for budgetary reasons. A new mission to Pluto and the Kuiper Belt is under study. For information on the "New Horizons" mission, see:

http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=2006-001A

The Pluto Kuiper Express mission as originally planned is documented below:

Originally designated the Pluto Fast Flyby (PFF), the Pluto Kuiper Express mission is designed to fly by and make studies of the planet Pluto and its satellite Charon in 2012 and fly on to encounter one or more of the large bodies in the Kuiper belt beyond the orbit of Pluto. Its major science objectives are to: (1) characterize the global geology and geomorphology of Pluto and Charon; (2) map the composition of Pluto's surface; and, (3) determine the composition and structure of Pluto's atmosphere. The mission is intended to reach Pluto before the tenuous Plutonian atmosphere can refreeze onto the surface as the planet recedes from the Sun. Studies of the double-planet system will begin 12-18 months prior to closest approach. Most aspects of the mission are still under study and subject to change.

Spacecraft and Subsystems

The overall structure of the spacecraft is an aluminum hexagonal bus with no deployable structures. Of the total 220 kg mass of the spacecraft, only about 7 kg will consist of science instruments. Power will be provided by radioisotope thermal generators (RTGs) similar in design to those used on earlier missions (e.g., Galileo or Cassini). Current plans call for the use of spare RTGs from Cassini. Communications will be via a fixed, 1.47 m high-gain antenna employing an X-band uplink receiver and downlink transponder. Pointing control will be maintained by a wide-field star tracker and a set of three solid-state rate sensors. The on-board computer is a 1.5 MIPS RISC-based system capable of processing a science data stream of 5 Mbps. The solid-state data storage system is capable of storing 400 Mb in both compressed and uncompressed formats. Data storage capacity and transmission rates will allow the transmission of 1+ gigabit of science data over a one year period. Planned experiments for the spacecraft include 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.

Mission Profile

Launch of the Pluto Kuiper Express spacecraft is to be on either a Delta or from the Space Shuttle, tentavely scheduled for December 2004. Current plans are 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 will be about 15,000 km. The flyby velocity will be 17-18 km/s. The infrared spectrometer requires a spatial resolution of 5-10 kilometers per pixel. Studies of Pluto's neutral atmosphere will 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 will 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.