Development of a Dedicated Launch System for Nanosat-Class Payloads

This paper addresses the objectives and preliminary development of a Nanosat Launch Vehicle, with attention given to payload accommodations and user issues. This system is intended to provide cost-effective, dedicated launch services for the very low end (10 kg or less to low Earth orbit) of the small satellite market. Such a capability would put small payload developers fully in charge of their destiny for the first time, freeing them from many of the technical, administrative and scheduling constraints associated with current secondary and offshore launch opportunities. Unlike many other proposed future launch systems, this launch vehicle project is based on an existing flight test program that is already manifesting academic payloads while also pioneering the demonstration and evaluation of advanced technologies that include composite propellant tanks and aerospike engines. BACKGROUND / INTRODUCTION The California Launch Vehicle Education Initiative (CALVEIN) is a joint university-industry partnership between California State University, Long Beach (CSULB) and Garvey Spacecraft Corporation (GSC). The initiative’s primary goals are to develop, test and evaluate advanced launch vehicle technologies while also providing hardware experience to the next generation of aerospace engineers. Frequent field testing is a CALVEIN hallmark. Notable accomplishments include the first-ever flight tests of a powered liquid-propellant aerospike engine. 3, 4 To facilitate the process of identifying and defining requirements for such technology development, the CALVEIN team has baselined a two-stage, expendable Nanosat Launch Vehicle (NLV) as its long-term focus. 5, 6 The distinguishing feature of this NLV is that it addresses the very low-end segment of the small payload market, i.e. – delivery of nanosats and picosats of up to 10 kg to low Earth orbit (LEO). This contrasts with other small launch vehicle programs that are attempting to deliver on the order of 100’s of kg to LEO, with a comparable increase in per-mission cost, or else are concentrating on flying humans to the edge of space. 8, 9 Another distinction is that the CALVEIN NLV effort is based upon an active flight test program that is already manifesting payloads from representative small satellite organizations (Figures 1 and 2). Such interaction is essential to creating a launch service that is truly responsive to the needs of the small satellite user community. Figure 1. Prospector 4 Flight Test 2 (photo by D. Gaylord) Garvey 18 Annual AIAA/USU Conference on Small Satellites 1 Figure 2. USC Payload Flown on the Prospector 4 NANOSAT LAUNCH VEHICLE DESIGN The basic expendable, two-stage NLV configuration is presented in Figure 3, along with first-order requirements in Table 1. The vehicle has a gross lift-off mass of only 1,540 kg (3,400 lbm), with a diameter of 65 cm (26 in.) and a length of 837 cm (330 in.). Figure 3. Pressure-fed Two-Stage NLV (dimensions in cm) At this scale, the NLV is readily transportable. Mobility is further enhanced by the fact that the vehicle propellants are chilled industrial gases (oxygen and propylene) that are widely available. Also, the baseline mission uses a direct insertion trajectory so that all events occur in sight of the launch complex, thus enabling telemetry, tracking and command (TT&C) functions to be accomplished from a single ground station. Combined, these features make it possible to operate the NLV with minimum investment from almost any launch site that has the appropriate range clearances. Table 1. Top-Level Performance Requirements and Design Constraints Deliver 10 kg to polar 250 km orbit Use direct orbit insertion trajectory LOX/hydrocarbon propellants* Pressure regulated helium propellant feed systems for both stages Single primary engine per stage Same diameter for both stages Both stages are expendable * initial calculations have assumed RP-1 as the fuel. Future iterations will consider propylene instead. A key design strategy for reducing cost and improving reliability is the elimination of the need for expensive turbopumps through the use of lightweight composite propellant tanks, higher performance propellants and/or an aerospike engine on the first stage that could potentially provide superior performance relative to standard bell-shaped nozzles. Furthermore, liquid propellants enable a non-hazardous work environment around the vehicle right up until the time of the final countdown. Their higher specific impulse is also an advantage over other propellant combinations that feature nitrous oxide or hydrogen peroxide as the oxidizer. Additional details regarding major design approaches can be found in Reference 6. dia. = 65 PAYLOAD ACCOMMODATIONS The CALVEIN team recognizes that payload accommodations is a critical area in the implementation of a viable operational NLV. Consequently, a preliminary NLV User’s Guide is in development that documents and communicates important user-related requirements, performance parameters and standard offerings and options. Present plans call for initial release during the fall of 2004. Potential NLV users are encouraged to become engaged in the preparation of this document. The status of several of these major hardware-related payload accommodations items are discussed below. Garvey 18 Annual AIAA/USU Conference on Small Satellites 2