It's not opinion. Planetary surveys are invariably done by ground teams. Orbital sensor surveys of the type done by Grissom in TSFS and Enterprise in "Pen Pals" make the most sense as "first look" examinations to answer very specific questions.
And if it takes an away team to conduct a survey, it necessarily takes MANY away teams to survey an entire planet.
Why not? Starfleet's mission is to explore new worlds, not explore new meadows on the east side of riverbanks. To answer a handful of very specific questions about a particular organism or feature, sure, a small science vessel would suffice. Exploring an entire planet, however, is a massive undertaking.
And it needs to be understood that, more often than not, specific points of interest will not be identified until the planet has been thoroughly explored in detail. Imagine, for example, an alien race trying to explore Earth. Somewhere in their civilization is a scientist who is looking for signs of rudimentary social intelligence in avian life forms; since the science team only explored a stretch of forest in Montana for a handful of weeks, this researcher will never have an opportunity to study the Superb Bird of Paradise in New Guinea; he'll never even know it exists.
And continuing to use Earth as an example: of the many thousands of species of plant and animal life on land and in Earth's oceans, any survey mission seeking to examine all of them in any amount of detail would have to visit hundreds if not thousands of sites for days at a time, and examining deep ocean species--or even air-breathing whale species--would require specialized equipment and several low passes by shuttlecraft.
Yes, a survey mission specifically intended to examine the mating habits of north american chipmunks would require a very small number of researchers and a few months at most to complete. But I don't think it would be very efficient for Starfleet to explore planets one mile at a time, one species at a time, with a different mission for each one of them.
For cruisers, yes. At issue here is what exactly Starfleet finds interesting. In TOS this was never made especially clear; often enough it was natural resources like Tritanium or other minerals (a survey which obviously COULD be conducted from orbit) but more often than not we saw Our Heroes beaming down just to take snapshots of something that looked like a nice piece of scenery. TNG had very few examples of genuine planetary surveys; these were mostly Voyager-style orbital flybys with remote sensor readings.
Planetary exploration will invariably be vastly more intense, because what Starfleet finds interesting will probably vary significantly from what botanists/archeologists/paleontologists/zoologists/marine biologists would find interesting.
Actually, that's what PROBES are, and we know Starfleet has long range probes capable of warp speed. The ability to survey planets from orbit and identify points of interest on those planets necessarily precludes the use of a science vessel for that purpose; the unmanned probes can identify points of interest for another ship to come and check out later.
What, then, is the niche for small vessels like the Nova and the Oberth? Again: for examinations of very specific aspects of a planet or star, such a vessel would be ideal: you only need enough people on board to keep the ship running and occasionally beam down to the site of whatever individual thing it is you're supposed to be investigating. This is NOT equivalent to "exploring a planet," anymore than a summer trip to visit the Sears Tower is equivalent to "exploring Chicago."
A greater estimate is not forthcoming unless it's based on what we've seen on screen. Much has been made of the omniscience of Starfleet's sensor devices, but apart from the fact that they are only ever as sensitive as required by plot logic, the fact of the matter is MOST things that are done on a planet need to be done by an away team, at close range, with tricorders and lab equipment. The very EXISTENCE of these things--especially field kits used by science officers and medics--necessarily means that Starfleet technology is NOT up to the task over long distances. Same again for the existence of planetary probes: the existence of such implies that a starship's sensors, like any other sensor device, loose a certain amount of resolution over long distances.
So unless Starfleet has a sensor array that can immediately identify the presence of fossils, social intelligence, compare genomes and evolutionary traits, record vocalizations and behavior patterns of every species on the planet and--in the case of intelligent life--conduct detailed examinations of the cultural/linguistic/economic/religious interactions between all of the planet's inhabitants, and do all of this from ORBIT, an away team will be necessary.
And we have at least one datapoint that suggests such a thing simply isn't possible: whatever you may think of Klingon sensors, it remains the case that Kirk and the crew of the HMS Bounty had to use an old fashioned radio tag to track down George and Gracie. Finding them in the FIRST place seems to be a huge stroke of luck, as Kirk didn't expect there to be any humpbacks anywhere near San Francisco.
Which, easy as it may be, isn't exploration.
B.S.. With the extreme amount of variation of climate and animal life on OUR planet, it would be scientifically asinine to assume that any other M-Class planet anywhere in the galaxy is even superficially similar to ours. It would require extremely peculiar commonality over the course of a billion years of evolution just to produce types mundane enough not to warrant detailed examination.
To put that another way: the only way M-Class planets are similar enough not to require planetwide explanation is if all M-Class planets are little more than slightly modified Earths (sort of a variation of the "aliens are just humans with forehead ridges" thing) which would basically transform Starfleet's mission to "Explore familiar worlds, seek out normal life and civilizations, to casually go where no one can tell the difference."
No, DAVID volunteered to beam down to check it out. Esteban was strongly against the away mission, probably because there wasn't supposed to be any need to beam down in the first place and Starfleet was worried about "radioactive contamination" or something. Remember, the only thing unusual they found on Genesis was "an animal life form" which the device wasn't programmed to create. Most NORMAL planets--especially Class-M ones--are positively teaming with animal life forms.
And note that Grissom's sensors could not identify the life form, or even the number of life forms. If you can research an entire planet in detail from orbit, surely you can identify a lost Vulcan child on a planet devoid of all other animal life forms?
Probably so, but a larger and permanent orbital facility would have to be setup in order to study the planet ON SITE. Paleontologists don't do orbital scans and neither do botanists or Marine Biologists.
Geologic data, sure. Do you want to saddle those 80 people with the job of taking blood and tissue samples of every one of the planets 250,000 animal species?
That doesn't explain what the Yamato was doing so close to the neutral zone, or what the Odyssey was doing so close to Deep Space Nine.
