Why did the Enterprise-D not send a probe to look for Picard?

Question

In TNG Season 4 Episode 9 ("Final Mission"), the Enterprise D is in the middle of handling a radiation hazard near Gamelan V, when it learns that a transport vessel carrying Captain Picard has not arrived on Pentarus V.

Why could the Enterprise not send a class-8 probe (or two?) to the Pentarus system, to search for their missing Captain?

• The Enterprise-D carries such probes.
• They are capable of Warp 9.
• The Pentaran miner's transport was using a sublight-speed shuttle, so it could not have gone far from its rendezvous point with the Enterprise, and, in fact, that point must be in the Pentarus system.
• The Enterprise's speed traveling to Gamelan was only Warp 6, and it did not travel for very long (otherwise it would not have kept such a leisurely speed for a rescue mission).
• Class-8 probes carry a "standard sensor pallet". One would assume that would be able to locate the transport, or relevant lifesigns, on different possible locations in the Pentarus system.

Answer 1

They believed the Pentarans were on top of the situation.

Specifically, by the time they arrive in the Pentarus system, the miners have already searched the two habitable M-class planets and are planning to search the moons:

DATA: The only Class M planets in the system are Pentarus two and five, both of which have been thoroughly searched by the miners.

RIKER: Then we'll search them again.

DATA: Sir, there are also four moons in the Pentarus system that could support life.

RIKER: Have the miners searched them?

WORF: Not yet, sir.

A probe might not be of much use in an intensive search of multiple planets, depending on their maneuverability and how sophisticated their programming is - my impression was that you mainly send them off on a particular course and then wait for them to send back data. They aren't really designed for autonomously flying back and forth, carrying out a complex search pattern; for that task, the miners and their shuttles (or the Enterprise itself, of course) would be more suitable.

Answer 2

The answer you linked offers one key clue

Note that this object doesn't contain a warp engine, but rather a warp 'sustainer', meaning that it can only travel at the speed at which it was fired.

The implication is this isn't a ship but an "unguided missile" sensor. So you would have to

• plot a course for the probe
• run the Enterprise up to an appropriate warp
• launch the probe
• go back to whatever you were doing
• hope the probe finds something to relay to the miners. You only get one shot at it

In the meantime, Gamelan V is getting irradiated. The needs of the many outweigh the needs of the few, plus the miners were already conducting a search. If you didn't have a plot, it's probable that determined miners would have found them.

Answer 3

Starfleet probes are not very flexible or smart

A starfleet Class 8 probe is a missile loaded with sensors. Its entire job is to be fired at something interesting and report back in detail.

It lacks meaningful ability for sustained exploration or searching.

It lacks the intelligence to perform any sort of analysis. Let alone enough to consider whether the captain is say.. in this cave, or dead, or transformed into a strange lizard-monster in a starfleet uniform.

In short, a Class 8 Probe is not a Probe-Droid.

Far better to send people.

And if you're sending people anyway, why not back them up with a Galaxy Class explorer?