Hearings

Another important area of effort in tracking and data acquisition is that of supporting research and technology (fig. 240). The purpose of the supporting research and technology program is to provide for an orderly development of improvements to existing systems as well as new systems that are necessary to support increasingly complex and stringent spacecraft and mission requirements such as those of the planetary lander and orbiter programs. In addition, it is through the supporting research and technology effort that the total performance of our networks is improved which allows the collection of more scientific information per mission with a resulting direct decrease in the total cost per mission.

Several illustrative development areas are discussed below. Receiving antenna performance

Large antennas, such as those required for lunar and planetary missions, can deliver the maximum gain for which they are capable only if they are very accurately pointed at the space vehicle. Slight misalinements cause large degradations in the signal strengths received. Automatic target tracking systems, such as those used in radar, do not provide sufficient tracking precision to fully realize the full gain of these large antennas. Developments are underway to provide a system that will provide more precise tracking.

Another area that needs improvement in large antenna performance is the capability of receiving a wide variety of frequencies in order to be able to support a variety of spacecraft transmitting on different

SUPPORTING RESEARCH & TECHNOLOGY

OBJECTIVES:

• MEET FUTURE PROJECT REQUIREMENTS

• INCREASED DATA ACQUISITION PER MISSION

MAJOR AREAS:

• GROUND ANTENNA SYSTEMS

• GROUND RECEIVING SYSTEMS

• SPACECRAFT TRANSMITTING SYSTEMS

• DATA HANDLING

NASA T64-495

FIGURE 240

frequencies. Present multifrequency feed systems are not as efficient as single frequency feed systems and as a result cannot be used for many power-limited spacecraft. Developments are underway which double the efficiency of multifrequency feed systems.

Ground receiver systems

The most critical section of a ground receiver system is the preamplifier. This is the section that receives the very weak signals from distant spacecraft and conditions them for amplification and detection in later sections of the receiver. Any noise introduced by the preamplifier interferes with the spacecraft signal and limits the distance from which useful signals can be received and the amount of information that can be received.

Developments are underway to produce operational low-noise maser preamplifiers using supercooled refrigeration techniques. These developments are most necessary if we are to provide the maixmum data acquisition support for planetary and interplanetary monitoring probes.

Data handling systems

As indicated in previous sections, the quantity of data being received from spacecraft is continually increasing as they become larger, more complex, and longer lived. Ways must be found to handle and process these data so that they can be readily available for analysis. Automatic data processing systems are already in use but continued developments and improvements are required in order to increase efficiency to keep pace with spacecraft capabilities.

INDEX

Page

AACB (see also Aeronautics and Astronautics Coordination Board).

147

Ablation materials and shielding..

38, 181

AC-2 (ATLAS-CENTAUR).

155

Advanced Orbiting Solar Observatory (AOSO).

117-119

Contract with Republic Aviation Corp. for phase No. 1..

117