There would be procedures in place to recover a lost explorer in this case.
If a pilot is show down over enemy territory, but can't get a distress call out in time, he simply goes off the air. Back in Korea and Vietnam, at least, pilots were not in permanent communication with the home base. If they didn't 'say' anything on air for a while, that wouldn't be normal. Depending on how often Bob is expected to check in, the explorer HQ would know after a certain amount of time to look for Bob.
Other pilots look first
The obvious people to look for a shot down pilot are other pilots in the area. In your case, with other scouts already on the planet, this is the obvious solution. After Bob is off air for 30 zorks of time, Scout HQ tells other nearby scouts to go try to make contact with Bob.
One such system I am familiar with is the MOBi. Basically, when the MOBi gets wet, it starts sending a radio pulse every x seconds. The MOBi controller manages the devices, and determines if any are going off. The Navy also has bigger versions for the entire ship (i.e. if the bridge gets wet, the ship is probably sunk so start transmitting; this one is designed to signal satellites so you can probably find a sunken US Navy ship from the Moon or farther).
This could work two ways; each scout has a MOBi system that keeps track of all other scouts, or HQ has a system in space that monitors them. Instead of getting wet, some other condition (loss of power?) would activate the device. The device would, of course, have its own power supply.
Pilots in neutral territory carried blood chits to help ensure their safety once shot down. These were basically messages in the local language, explaining who the pilot was, and promising some sort of reward for keeping the pilot sage.
This would be a difficult subject with your explorers, depending on whether or not they wanted to get in touch with the local people. If they didn't mind making first contact, then scouts with be provided with some (self-powered) device designed to get in contact with humans (like the wireless methods stuff suggested in the linked question).
Send in the rescue squad.
If the downed pilot is found, then there would be some plan in place for getting him out. The US Air Force in Vietnam had specific helicopters ('Jolly Green Giant') and associated squadrons on hand to perform these extractions when needed.
After Bob doesn't make contact or 30 zorgs, and other scouts find him, the rescue squadron is sent to help.