What are some limitations to the search for life on other planets?

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answers:
Larry from the ferry say: Lack of oxygen and nitrogen
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Clive say: Others go on about distance... but let's look at what kind of planets might be the best ones to have life. A lot of which we can work out just looking from here.

Having liquid water would obviously be a good one. So how hot or cold is the planet? Maybe you can have life without it but it seems less likely.

Does it have a magnetic field? That's a big one for Earth. Our Sun throws out a lot of charged particles that can cause mutations and if too much of that gets down to the surface, you'll get too many and the evolution of life will be continually interrupted. The Earth's magnetic field is a good shield against those. Without it, it would be like living in the path of a nuclear bomb blast.

A big moon is a help. It stops the planet wobbling too much so the seasons stay the same for long enough for life to develop past being just bacteria.

The planet will have to be big enough so that its gravity can hold on to an atmosphere that living things can breathe. Otherwise you'd be looking at life that works a totally different way from us, if that's even possible.

And what's in that atmosphere? If there's some free oxygen in it, now it gets really interesting. Oxygen reacts with virtually everything so if you can detect some, there must be something that keeps producing it. The only thing we know of that does that is plants.
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William say: The biggest limitation of all is if there is no life on other planets.
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Starrysky say: The others concentrate on limitations of doing the search. Sounds like they consider searching to be pointless. My answer is more positive, stating if you do try to search, some factors would limit what would be the more promising candidates to search for.
Right type of star that planet orbits. Ones emitting hard radiation or are remnants of a supernova or just formed from a dust and gas nebula or are part of a multiple system are not high on the list to host a planet with life.
Planets within the zone (nee "Goldilocks") where liquid water might exist are more interesting.
Planets that are no phase locked (one face always toward the star) are not as interesting.
Gas giant planets are not interesting, but if a moon orbits it, that might fit the bill.
Planets that are too small in mass might not retain enough atmosphere to host life.
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? say: 1) we can not go to any other planet with our present rocket technology.
2) we can send robot probes to planets of this solar system. But they can only examine the surface area where they land. The rest of the planet is able to be explored.
3) planets of other star systems are so far away that we can barely detect them even using our largest telescopes. So finding life on one is near impossible.
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Ronald 7 say: Distance for a start
Time will always be a barrier
And how would we communicate ?
I mean just why a dog chases a car, what is it going to do when it catches it ??
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say: 1. Distance
2. Time
3. Communication method
4. Unknown if primitive or advance civilization
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say: distance is the main one but communication may be impossible , if they don't have radio we will never know about them if their electronics is based on a different material it may not be compatible , there may be billions of inhabited planets in the universe but if they can't transmit EM radiation we will never find them
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Joan H say: Distance and expense..
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BJ say: The distance from the earth
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CarolOklaNola say: Distance
Time
Language barriers

Limitations of our current technology, specifically pixel resolution. If one pixel is 30 square meters, You can't resolve a human being in that 30 square meters or individual humans. That is the resolution of Landsat Thematic Mapper images. Weather satellites have a pi el resolution of 8 square kilometers. That is roughly 5 square miles.

Oh, expense. If the James Webb Space Telescope never vets launched, a lot of people have spent more tha. 20, possibly 30 YEARS of their lives on that project, yet a paranoid Congress can stop that project.
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someg say: 1. Nobody cares; and 2. If they did care, there is not a thing they could do about it.
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Bill-M say: 1. Distance. We can't go there.
That about covers it.
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Nyx say: Sensitivity of current detection equipment.
Distance to host star, from Earth.
Closeness of exoplanet to host star.
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