Innovating sounding-rocket experiments and stimulating use of the rocket
Institute of Space and Astronautical Science (ISAS) has been launching small sounding rockets to conduct astronomical observations, plasma-physics observations, and upper-atmosphere research as well as microgravity experiments and engineering/technological demonstrations. Unlike large launch vehicles for placing satellites into earth orbit, small sounding rockets reach altitudes from approx. 150km (S-310) to 300km (S-520) at the highest. During their ballistic flight before the final splashdown, a variety of experiments are conducted, including atmospheric observations. A sounding rocket enables in-situ observations at altitudes too low for satellites and too high for balloons. Currently, several rockets are launched every year. As the period from project proposal to final launch is shorter for sounding rockets, many experimental research results in science and engineering have been achieved. The sounding rockets themselves also show progress with the latest technologies, such as integration of onboard avionics equipment and the introduction of a new attitude-control system. Recent upper-atmospheric research and the demonstration experiment of atmospheric reentry are detailed in the Forefront of Space Science.
Research on the Upper Atmosphere Region Using Sounding Rockets
(September 2012 issue)
Towards Realization of a Soft Atmospheric Entry Vehicle How was the Shiitake Mushroom-Type Experimental Vehicle Made?
(October 2012 issue)
The sounding rockets that we launch every year are expendable vehiclesEand are used only once. They splash down in the ocean after flight and are lost for good with their expensive onboard observation instruments. The recovery of the instruments is technically possible but, from experience, very troublesome. Thus, since new rockets and observation equipment need to be produced for every launch, the annual number of launches is limited.
How great is the demand for sounding rockets? A survey limited to research in atmospheric physics and microgravity science showed that there are more than 50 experiment proposals in five years, or about 10 launch requests for experiments a year. In the current situation where only two or three sounding rockets can be launched a year, it is difficult to satisfy all these requests in terms of cost and time. Considering such fields as engineering/technological demonstrations and life science, there is even more potential demand for sounding rockets.
There are also increasing demands for sounding-rocket technologies. For example, researchers have need of technologies such as atmospheric sampling as well as recovery of observation instruments and materials used in microgravity experiments. Other requests include: controllable observational directions, slower flight speed, lower/higher flight altitude, mass data storage/recovery, access to onboard observation equipment until the last moment before launch, etc. Researchers using sounding rockets are very particular about these matters. Superficial remodeling, however, will never bring dramatic improvements to the rocket operation. We rocket researchers must innovate the experimental environment from the viewpoints of demand and technology, and encourage greater use of sounding rockets.
If sounding rockets were reusableE/span>
To stimulate research using sounding rockets, we need innovation in the experimental environment through a drastic reduction of operating cost, so that participation in space experiments will increase significantly. To achieve this, there is a limit to what expendable rockets can do. ReusableEsounding rockets are the best way to meet usersEdemands.
Our proposed reusable vehicle will be capable of carrying a 100kg payload up to 100km and higher, the same as the highest altitude of the S-310 rocket, and returning to the launch site. One vehicle will repeat this flight 100 times. The launch frequency will be 10 times a year, in two separate series of five launches a year. It is also planned to build a system that enables turnaround operation of 24 hours at the fastest (i.e., one-day launches). This will not only significantly increase flight opportunities, but will also help achieve a qualitative improvement in the experimental environment by providing the rocket with unprecedented characteristics such as: (i) greater flexibility in trajectories and altitudes; (ii) subsonic flight and quasi-resting state at high altitude; and (iii) recovery and reuse of observational instruments.