<bold>Access to Space for Technology Validation Missions: Exploring Possibilities of Suborbital Flight</bold>

Space technology experiments and validation missions share a common dilemma with the aerospace community in general: the high cost of access to space. Whether the experiment is a so-called university cubesat, a technology experiment, or a NASA New Millennium Program (NMP) technology validation mission, the access to space approach must be scaled appropriately: a cubesat might fly as one of a number of cubesats that negotiate a flight on an experimental vehicle; a technology experiment might do the same; a NASA flight validation might partner with another NASA or Air Force experimental mission.(1,2) But are there other options, and what are the benefits of one approach over another? What are the limitations of one approach over another? How can one assess the viability for a particular experiment? How does one go about acquiring such a space access? What experiments originally considered for space-flight might be validated instead in a suborbital environment? New vehicles, most notably unmanned aerial vehicles, are pushing existing capability to higher and higher altitudes and longer duration flights. Reliable suborbital flights and long-used balloon flights can now be applied to new, different payloads as the technology needs change over time. So what are the similarities and differences between the space and suborbital flights? Where are these programs managed, and with what capabilities both existing (proven) and new? This guide is written for the space experimenter seeking an understanding of the issues which will drive a large part of the design of a space experiment - the method of access to space. Since this is, indeed, rocket science, this guide can only serve as a starting point for the reader. The range of suborbital capabilities is so broad - flights cover an altitude range from 3 km to 1400 km, the payload weight from 1 to 3600 kg, the flight time from 5 min to more than 100 days, and the cost from few thousand to tens of millions of dollars - that farther research and data will be required. This paper can only point the way to the start of an assessment. With the range of flight possibilities so broad (a dilemma of too many parameters and too many unknowns), two constraints are established to provide a reference for discussion: 1) Earth science measurements are presented as an example of the range of space flight needs as they can apply to the suborbital regime. 2) A sample set of space technologies is considered in the suborbital regime. With these constraints in place, a framework is established to compare and contrast these different suborbital options.