*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 goal is to minimize path loss to improve communication quality. Let's examine the choices:

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

1. **Why the correct answer is correct:**
   - **Perigee** is the point in the Moon's orbit where it is closest to Earth. When the Moon is at perigee, the distance between the Earth and the Moon is minimized.
   - Path loss in radio communication is directly related to the distance between the transmitter and receiver. The formula for free-space path loss (FSPL) is:
     $$ FSPL = 20 \log_{10}(d) + 20 \log_{10}(f) + 92.45 $$
     where:
     - $d$ = distance in kilometers
     - $f$ = frequency in MHz
   - By reducing the distance $d$, the path loss decreases, making communication more efficient.

### Why the other choices are incorrect:

2. **B: When the Moon is full**
   - The phase of the Moon (e.g., full moon) does not affect the distance between the Earth and the Moon. Therefore, it does not influence path loss in EME communications.

3. **C: When the Moon is at apogee**
   - **Apogee** is the point in the Moon's orbit where it is farthest from Earth. At apogee, the distance is maximized, resulting in greater path loss according to the FSPL formula.

4. **D: When the MUF is above 30 MHz**
   - The **Maximum Usable Frequency (MUF)** is a concept related to ionospheric propagation, not EME. EME communications typically occur on VHF, UHF, and microwave bands, where the MUF is not a limiting factor. Therefore, this choice is irrelevant to EME path loss.

In summary, scheduling EME contacts when the Moon is at perigee minimizes the distance and thus the path loss, making it the optimal condition for such communications.