Trajectory options for Ice and Fire Preproject missions utilizing solar electric propulsion

Abstract

The Ice and Fire Preproject defined the first mission set of the Outer Planets/Solar Probe Program consisting of the Europa Orbiter, Pluto-Kuiper Express, and Solar Probe missions. The development of low cost, high performance spacecraft and propulsion systems, in conjunction with the desire to minimize launch vehicle requirements, has been a tremendous challenge. Recent developments in one area of propulsion, Solar Electric Propulsion (SEP), may provide a stepping stone to advanced propulsion systems for future missions. Preliminary mission design software was used to discover and analyze SEP trajectories for the Ice and Fire missions. Potential benefits to the delivered spacecraft mass, in conjunction with the use of small, low cost launch systems, were examined. Unfortunately, the constraint on solar distance limits the benefits of SEP for outer solar system missions. Also, the requirement of a large bi-propellent propulsion system for Europa Orbiter, in addition to the SEP system, strongly reduces any potential benefits. SEP may offer potential benefits for PlutoKuiper Express and Solar Probe, but at the cost of system complexity. Although the current technology may not provide benefit for these particular missions, the potential of SEP, and electric propulsion in general, for other future missions is significant. * Mission Design, Launch System, and Spacecraft System Engineer, Outer Planets / Solar Probe Project, Member AIAA. t Member of Engineering Staff, Navigation and Flight Mechanics Section, Member AIAA. Copyright © 1998 The American Institute of Aeronautics and Astronautics, Inc. The U.S. Government has a royaltyfree license to exercise all rights under the copyright claimed herin for Governmental Purposes. All other rights are reserved by the copyright owner. INTRODUCTION In the current National Aeronautics and Space Administration (NASA) budget plan, there exists a new proposed program aimed at opening the outer solar system to new robotic science missions. This program is called the Outer Planets / Solar Probe Program and is currently planned to begin in fiscal year 2000. The first mission set of this program, the Ice and Fire missions, includes three very challenging missions which are sure to set the standard for future missions to the outer solar system: Europa Orbiter, Pluto-Kuiper Express, and Solar Probe. (NOTE: Since the submission of this paper, the Ice and Fire Preproject has gained project status and is now called the Outer Planets / Solar Probe Project.) The Outer Planets / Solar Probe Program will make use of the latest technology in order to develop low cost, high performance spacecraft. The NASA sponsored Advanced Deep Space System Development Program (ADSSDP, often referred to as X2000) is chartered to develop this technology, in conjunction with industry partners. This program will focus on advanced avionics, integrated microsystems, and advanced power systems. This technology will provide the foundation upon which missions to the outer solar system will rely for developing spacecraft to be sent to these new and exciting destinations. The Ice and Fire missions plan to make use of these developments by flying the same avionics and core software on all three missions. In following with the philosophy of faster, better, cheaper, missions to the outer solar system pose many difficult challenges, including those of extended lifetime, severe radiation environments, telecommunications and operations over long distances, and spacecraft autonomy. Probably the most difficult challenge is in the development of low cost, high performance propulsion systems, which are required for some of these missions, in con-