Easy come, easy go.

Four days after a successful "Galactic 05" space tourism launch ignited a rally in shares of Virgin Galactic (SPCE 3.15%), the space tourism pioneer saw its stock drop on Monday, closing down 8.6%.

That's not enough to erase all the stock's gains from news of its launch -- Virgin's sixth successful spaceflight in a row in the past six months, and its fifth flight carrying paying passengers. But the decline did erase Friday's gains, and has already dropped the stock back below where it ended on the day of the flight itself.

Investors looking ahead to Wednesday

Why isn't Virgin Galactic able to hold on to its gains? Perhaps it has something to do with the fact that on Wednesday, the company is scheduled to report its Q3 earnings, and the news won't be great.

According to analysts polled by Yahoo! Finance, Virgin Galactic is probably looking at a $0.43-per-share loss for the quarter on a mere $1.1 million in quarterly revenue -- not a lot of money coming in for a company that's sending $150 million per quarter out the door on operating expenses alone, according to S&P Global Market Intelligence data.

A positive surprise is possible

And yet, there's a distinct possibility that Virgin Galactic will surprise investors to the upside when it reports revenues on Wednesday.

Consider: Management has told investors to expect only about $1 million in revenue for each of Q3 and Q4 -- a lowball number that probably explains Wall Street's conservative estimate. And yet, we know that Virgin Galactic's flights so far in this series have been carrying three paying passengers per liftoff. We also know that Virgin Galactic conducted two such flights in Q3 (Galactic 02 and Galactic 03), and two more (Galactic 04 and Galactic 05) in Q4.

At ticket prices believed to range from $200,000 to $250,000 per seat, this implies that at minimum, Virgin Galactic's Q3 revenue should be six seats times $200,000 each, or $1.2 million -- and revenues could theoretically be as much as six seats times $250,000 each, or $1.5 million. Q4 revenues should track a similar range.

Long story short, unless somebody flew entirely for free, Virgin Galactic should certainly exceed expectations on Wednesday -- for revenues at least, if not for earnings. This doesn't change the big-picture story on the stock, that it's not bringing in anywhere near enough revenue to pay for its costs. But it should be enough to allow Virgin Galactic to "beat earnings" a couple days from now.

Investors who are selling the stock today may simply not have figured this out yet.