The next Energetic Particles EXPLORER is beginning environmental tests in preparation for a launch during midcalendar year 1964. The first Atmosphere EXPLORER, EXPLORER XVII, was launched on April 2, 1963, and transmitted scientific data for 99 days (its full design life). The second Atmosphere EXPLORER will contain modifications of the scientific instruments carried on EXPLORER XVII. Improvements in the new spacecraft are presently being planned to increase its data recording capability and operating lifetime thus permitting measurements of greater latitude and altitude coverage than was possible with EXPLORER XVII. This spacecraft will be launched in a polar orbit by a DELTA vehicle from the Atlantic Missile Range during the first half of calendar year 1965. An Air Density EXPLORER was launched from the Pacific Missile Range on December 19, 1963, and named EXPLORER XIX. Development effort is continuing on the Air Density/Injun EXPLORERS with launches scheduled for the second and fourth quarters of calendar year 1964. The first Beacon EXPLORER is scheduled to be launched by a DELTA vehicle by the first quarter of calendar year 1964.* Environmental testing of flight unit No. 2 is scheduled for completion prior to shipment of the unit to the launch site. This unit will be launched in a nearly polar circular orbit at an altitude of approximately 600 miles. Approximately 150 participants from 20 countries and representing 80 observing stations are involved in this project. Final calibration tests on the Ionosphere EXPLORER have been completed at the Airborne Instruments Laboratory, Deer Park, Long Island, N.Y. Preparations are in progress for a launch during the first half of calendar year 1964. All testing and calibration of the International Satellite (United Kingdom No. 2) have been completed. This launch is also scheduled for the first half of calendar year 1964. A sounding rocket test of the San Marco payload is scheduled during the next few months from the Italian San Marco platform. This launch will take place off the east coast of Africa in equatorial waters. It is a precursor to satellite launchings by SCOUT vehicles from Wallops Island and later the San Marco platform. Sounding rocket status. Sounding rockets continued to play an important part in the exploration of the space environment during the past year, as indicated in the following table: ⚫ Launched on March 19, 1964, but did not achieve orbit. Sounding rocket status Experiment or program (experimenter) Participation in 2d COSPAR International Ionosphere studies during solar eclipse (Geo- Atmospheric composition studies using the (Johns Hopkins University, Fastie).......... (Jet Propulsion Laboratory, Barth). Thermosphere probe (Goddard Space Flight D-region studies (Goddard Space Flight Correlation shots with: EXPLORER XVII. ALOUETTE... Air density sphere drag (University of Temperature studies in noctilucent clouds... A partial listing of sounding rocket missions being readied for the next year is given below: It is also anticipated that a mobile expedition will be organized to take soundings in the broad ocean areas not presently covered with present launch capability. Of specific interest is the electrojet in the ionosphere above and along the geomagnetic equator. PIONEER status.-The PIONEER shown in figure 116 is intended to obtain detailed measurements of the fields and particles environment in interplanetary space and to determine the effects of solar activity upon that environment. For maximum utility, the measurements should begin during the International Years of the Quiet Sun, both to evaluate "baseline" conditions and to coordinate with other activities during this period. The results from PIONEER are expected to provide data which are required by APOLLO and by advanced projects in the planetary program. The management of this project is through the Ames Research Center. Since August 1963, the Space Technology Laboratories, Los Angeles, Calif., has been operating under letter contract to accomplish the design and development of four spacecraft. It is anticipated that the contract will be definitized early in 1964. A total of seven experiments have been selected and are currently under development. Four of these are definitely planned for the first and second flights. The remaining experiments are in a tentative category contingent upon spacecraft integration, compatibility with total available power and telemetry, and the final definition of total allowable weight for the spacecraft. The first launch is being planned for early in 1965. Orbiting Geophysical Observatory (OGO) status.-The OGO, shown in figure 117, is a member of the family of third-generation scientific satellites which provide the capability for supporting increased payload weight in orbit. This observatory, with its standardized structure, attitude control, thermal control, power supply, communications, and data handling subsystems, can carry 20 investigations, weighing a total of 150 pounds, in the simultaneous study of the related phenomena I have been describing. Figure 118 depicts recent OGO activity at the Space Technology Laboratories, Inc., Los Angeles, Calif., where, under the technical direction of the Goddard Space Flight Center, the spacecraft develop ment, assembly, and test of three flight observatories are nearing completion. The observatory test model is undergoing a thorough program of system and environmental qualification. The "first flight" observatory is now completely assembled and with its complement of 20 scientific investigations is in the final test phase. The "second flight" observatory is in the process of being assembled prior to entering the detailed test portion of its schedule. The first OGO was to be launched in late 1963; however, technical difficulties and the realization that a thorough test program would require longer than we had originally planned delayed the mission to mid-1964. To support scientific objectives, we are planning to launch an average of two OGO's each year; one into a low, near-Earth orbit and one into a high altitude orbit. Currently we have initiated the procurement of three additional spacecraft and the selection, from proposals submitted by the scientific community, of the payloads for the fifth and sixth missions. Future plans The flight programs planned for the next 2 years that will contribute to our knowledge of the space environment are EXPLORERS and sounding rockets, Orbiting Solar Observatory, Orbiting Geophysical Observatory, MARINER-MARS, and PIONEER. Objectives SUN-EARTH RELATIONS Our investigations of Sun-Earth relations are to advance knowledge about the Sun and solar activity, and their influence on the Earth. The Sun exerts a controlling influence over the Earth's atmosphere, ionosphere, and magnetosphere. Solar energy is the principal support to life on Earth. The Sun dominates the interplanetary medium, exerting its influence on the Earth and the other planets by means of electromagnetic radiations, protons, electrons, other charged particles, and magnetic fields. Thus, an investigation of Sun-Earth relations contributes to our knowledge of the space environment, directly supporting our efforts to advance our space capabilities, to develop manned space flight, and to make applications of space. These investigations are important to our understanding of weather, of atmospheric behavior and climate, of the ionosphere, magnetic storms, and aurora, and their influence on radio communications, Inasmuch as solar proton beams are probably the greatest radiation hazard to crews in space, an ability to predict the time of their occurrence, or alternatively the times when they will not occur, would be of considerable value to the manned space flight effort. Only by thorough study of solar flares and solar activity can such an ability be developed. Progress The progress in this area was interrelated to a certain extent with the progress in the investigation of the space environment as discussed previously. However, the outstanding achievement of the past year, beyond that which contributes to our knowledge of the space environment, was the great advance in solar physics obtained from the |