What happened

Shares of rocket developer Astra Space (ASTR -1.67%) stock tumbled 12.1% as of 3:30 p.m. EDT Tuesday for reasons unknown.

But we can guess.

A model rocket ship on top of a digital financial chart.

Image source: Getty Images.

So what

Last week, space special purpose acquisition company Astra suffered its sixth straight failed rocket launch when a rocket that should have gone straight up from its launch pad in Kodiak, Alaska, instead first shuffled sideways, then finally took off, but failed to reach space. A failed engine appeared to have been the cause.

Over the weekend, a second rocket start-up -- this time from Firefly Aerospace -- suffered a similar failure when one of its engines prematurely shut down.  

Now what

Granted, Firefly is not Astra, and the failure of both companies to reach orbit, even in launches that happened in quick succession, was not linked. Nevertheless, the proximity in time of the two failures may have reminded investors in these (still unprofitable) space companies that space is hard, and success isn't guaranteed.

Investors should keep in mind, moreover, that even once the companies succeed in reaching orbit -- and I believe they will, in time -- their success at earning profits in an increasingly crowded field such as space launch has even less guarantee of success.