If you can't figure it out, I really like this story. The question of how we communicate with alien races hasn't been covered enough. In Star Trek TNG we get a few hints of how hard it is. But in the end, it's the universal translator that solves the problem. This story does remind just a little (very little) of the movie "Enemy Mine" 1985 - which see two enemies of a space war, stranded together - and having to learn and trust each other.

This story, might be a pre-cursor to that - Where "we" are at war, and just getting started exploring space - with the goal to learn about different scientific advances, among other things.

But one of the very first lines in the story is: "A smile of friendship is a baring of the teeth. So is a snarl of menace. It can be fatal to mistake the latter for the former.

Harm an alien being only under circumstances of self-defense.

TRUST NO ALIEN BEING UNDER ANY CIRCUMSTANCES.

—From Exploration Ship's Handbook."

There are only 15 ships at the start of the book, and that is quickly cut down to 6. The two man crew of these ships are identical twins. This is important, because the Johnny the twin of our lead character Paul is killed by what turns out to be an intelligence species of cat (or cat like creatures).

The planet that they land on is baked with red light from their sun, and the in inhabitants see mostly the infrared spectrum. To human eyes the planet is dull red. Contact is made with the home base, where we learn most of these facts.

What is interesting here, is how we also learn how Johnny is kill, his brother names the planet "Johnny's Planet" in honor of him. We also get what appears to be a throw away line about telepathys.

Of course in order for humans to see, they have to use white light. The natives can't see the white light, but it turns out it has an effect on them.

The one native that Paul has been trying to learn a common language from is dying. Paul tries to say he wasn't the cause. But it suddenly occurs to him, that he maybe - the white light maybe doing harm. And if he had only trusted enough to go to the city with his teacher - and use a flashlight or small lantern this could have been avoid. Paul knows how to cure his teacher thou, but convincing the other natives that he needs to take Thoon inside the ship turns out to be impossible. Mistakes are make by both sides. But Paul is able to get Thoon inside.

Here is where the story really gets good. The cat like creatures, turn out to be intelligent. And one has been on the ship, they want to learn how to fly the ship and leave.
It turns out these creatures are telepathic. This is were it gets really really good - I want to say so much more.... But here the thing if I say the end you may not want to read the story, and the story needs to be read...... so I'll leave it at that - go read the story. :-)

www.gutenberg.org/ebooks/23799