Double which in one sentence

[goodboybkk]

Is it okay to write which, then another which?

There is no need for landing and a deployment, and also because the lunar orbital period is two hours, we can use solar power, which is much simpler than doing it on the lunar surface, which, if you want to observe during the lunar night, then you have to provide the energy for almost 14 days

China wants to launch a moon-orbiting telescope array as soon as 2026

The satellite constellation circling the moon would enable scientists to peer into the universe's early days.

www.space.com

 

[tedmc]

The sentence is too long. Split it; it reads better and you solve the problem of two "which".

There is no need for landing and a deployment (of?), and also, because the lunar orbital period is two hours, we can use solar power (for?) , which is much simpler (easier) than doing it (doing what?) on the lunar surface. which Besides, if you want to observe (the moon?) during the lunar night (what's that?), then you have to provide the energy (for?) for almost 14 days.

 

[Tarheel]

I see nothing wrong with using "which" more than once in a sentence. However, your sentence is confusing.

The question you should ask yourself is does it say what you want it to.

 

[goodboybkk]

How about this :
Some poor students use usingenglish.com, which is virtually free, which is good for them since they cannot afford to pay even $1 for English tuition.

 

[Tarheel]

It's OK (more or less). However, I would delete "English" there. . (Apparently, you wanted to use the word "virtually".)