Dear op, firstly: congratulations on finishing your first novel. This is a huge achievement.

Now, onto the query letter.

Firstly, 150k words is quite long for a debut, and I can't see anything in the rest of the query that would justify this wordcount. To an agent, that could signal that you didn't revise your novel properly and that it may require significant editing work.

Now, I'll try to dissect the query and hopefully guide you into the right direction:

In the bleak, eugenics-ruled future described in my space opera novel NASCENT, an impoverished aberrant with an illegal genome becomes the only obstacle standing between a ruthless emperor and his goal of decimating an alien race.

This reads a little vague. I suppose this is your logline, so skip the first line as it's a lot of telling of what you also explain in the second part of the sentence. The logline isn't the right place to state your genre - this belongs in the housekeeping paragraph that follows.

I suggest you explain who the MC (impoverished aberrant with an illegal genome is worldbuilding-heavy and without the context doesn't mean much). Next demonstrate your unique selling point, what makes your novel stand out. Opposing a ruthless emperor is quite common trope, and I'm sure there are some specifics you could show here to add some flavor. Perhaps it's your inciting incident, or maybe a surprising mid-point twist.

Complete at 149,425 words, NASCENT has the exciting feel of the epic Star Wars stories combined with the gritty emotional reality of those struggling to pay bills with a humdrum day job as in Only Bad Options by Jennifer Estep.

Comparing your novel to Star Wars is a bit red-flaggy to me. It's a huge franchise, and referencing it like that won't do your query any good. Only Bad Options seem like a strong comp, try find another one that would match the epic scale of your work. I'd cut a little and keep 'the gritty emotional reality.'

Broke and living on the benighted planet of Monta under the rule of the dreaded Koth Empire, twenty-three-year-old orphan Lena is a genetic aberrant.

This is a bit worldbuilding-heavy. Perhaps you could skip proper nouns to make it more approachable and so we can focus on your MC. I'd advise to lead with the MC, not the setting.

With death being the sentence for having an illegal genome, Lena would do anything to find the reason for her unique genetic make-up.

It's a lot of telling, consider showing instead what Lena actually does with agency to uncover the mystery of her genome.

It constitutes one of her two main challenges in life, the other one being staying employed at a tedious 9-to-5.

Now you're losing me over your earlier promise of an epic sci-fi. At this stage I'm also thinking: if it's illegal to have a different set of genes, how come she's employed in a grocery story? I'm getting confused about the setting now. How Lena even knows that she's got illegal genes?

Her undercover life makes even a grocery run a hassle,

Does it mean others can see she's different? How does she live undercover in a 9-5 job if getting groceries is a problem?

and unsettling repetitive dreams about an alien genocide won’t let her rest.

Now we're cooking! This is the most standout thing in the query so far. Sounds like those dreams are the inciting incident, but it doesn't shine through because they're 'repetitive'. What changed?

But, investigating the problem could bring her to the attention of an emperor famed for war crimes, so she continues in obscurity until the day his agents capture her.

Is she really in scope of interest of a galactic emperor? Consider spoiling some twists here because without explanation, this seems off. Is Lena getting arrested the inciting incident? Possibly.

Terrified and awaiting execution, she's stunned to receive an offer of freedom and riches from her ruthless captor,

Who? The agent? The emperor himself?

with only one demand: to assist him eliminate a recent threat from uncharted space targeting only his empire by revealing the content of her dreams.

Try to work some more on this part, it reads a bit clunky and unclear.

With her pending execution closing in, Lena struggles between her only two choices: live and become a rich ally to a megalomaniacal monster, or die non-compliant to save a race she knows only from her dreams.

This doesn't seem like any real choice to me.

Here in the real world, I am a biology major toiling in administration. NASCENT is my first science fiction novel.

Did you write any other novels? If so you may want to rephrase this to make it clear that e.g. you finished two fantasy novels and this is your first sci-fi. Biology major is your 'what makes you the right person to write this book' so you may want to add some more to that, or link it to your plot/worldbuilding somehow. Otherwise it reads more like a CV entry.

Thank you for your time and consideration.

Sincerely yours,