*Question E3A03:
When scheduling EME contacts, which of these conditions will generally result in the least path loss?*  

*Correct Answer is  A: When the Moon is at perigee*  

### AI Response: (may contain errors)  

When scheduling Earth-Moon-Earth (EME) contacts, the condition that generally results in the least path loss is when the Moon is at perigee.

### Explanation of the Correct Answer:
- **Perigee** is the point in the Moon's orbit where it is closest to Earth. At this position, the distance between the Earth and the Moon is minimized, which reduces the path loss for signals traveling to and from the Moon. The formula for free space path loss (FSPL) is given by:

$$
FSPL = 20 \log_{10}(d) + 20 \log_{10}(f) + 32.44
$$

where:
- $d$ = distance in kilometers
- $f$ = frequency in MHz

Since the distance $d$ is smaller at perigee, the path loss is lower.

### Why the Other Choices are Incorrect:
- **B: When the Moon is full**  
  - The phase of the Moon (full, new, etc.) does not significantly affect path loss. While a full Moon may provide better visibility for optical observations, it does not change the distance to the Moon.

- **C: When the Moon is at apogee**  
  - Apogee is the point where the Moon is farthest from Earth. This increases the distance $d$ in the FSPL formula, resulting in greater path loss compared to perigee.

- **D: When the MUF is above 30 MHz**  
  - The Maximum Usable Frequency (MUF) relates to ionospheric propagation and does not directly affect the path loss for EME contacts, which primarily depend on the distance to the Moon and the frequency used. While higher MUF can improve ionospheric communication, it does not impact the EME path loss directly.

### Summary:
- The least path loss for EME contacts occurs when the Moon is at perigee due to the reduced distance.
- Other factors like the Moon's phase and MUF do not significantly influence the path loss in EME communications.