tion. The numbers chosen were conservatively selected at two times the velocity increment required for an impulsive transfer. Thus the velocity increment or aV numbers shown in Table 1.3, and subsequently the propellant requirements to provide those velocity increments, are probably somewhat higher than the amounts which will be ultimately decided upon. However, this overestimate in cost will be somewhat offset by the increase in mission operations cost due to the lengthened disposal mission time resulting from the cost optimization of the trajectory mode. 6.2 Disposal Costs There are four principal elements of dispoal costs: 1. The cost of modifications to the SPS satellite to ready it for the disposal mission. These costs include added thrusters, propellant tankage, controls and so on. Depending upon the state of salvage of the satellite, some structural modifications for adaptation of an EOTV may be necessary. 2. The cost of propellants. 3. The cost of transporting propellants to the SPS satellite in geosynchronous orbit. 4. The cost of mission operations. Assuming argon to be the propellant and a specific impulse of 10,000 s, 342 MT of propellant is required for each km/s of velocity increment imparted to a full-scale SPS satellite. The cost of argon is presently $240 per MT thus resulting in a cost of propellant of $81,960 per km/s of velocity increment imparted to the satellite. Taking the cost of cargo transportation from earth to GEO to be $50,080 per MT, the cost of transporting propellants to the SPS satellite in GEO is $17,102,000 per km/s of velocity increment imparted to the satellite. The cost of modifications to the SPS satellite in preparation for the disposal mission is obviously somewhat variable. A reasonable estimate for this cost can be
RkJQdWJsaXNoZXIy MTU5NjU0Mg==