The global science community was ablaze with the news last week that the European Space Agency (ESA) has put a satellite called Rosetta into orbit around an icy comet that has been traversing the universe for nearly 5 billion years. That’s a stunning achievement in itself, but within the next few months the ESA will take things a step further: It will attempt to drop a lander armed with an array of sophisticated equipment on the comet’s surface. 

Why would scientists spend more than a decade and nearly $2 billion to chase down a comet? Formed around the same time as the outer planets of our solar system, comets could tell us important facts about the origins of our solar system. For example, water could be found that could help explain how life began, or new minerals could be discovered.

Orbital Sciences Corp. (NYSE: ORB) isn’t directly involved in such sexy programs as discovering how the universe began, but it is the workhorse of the space program. Located in Northern Virginia, just outside of Washington, DC, the company is the industry leader in designing and producing small- and medium-class space and rocket systems.

It has launched more than 1,000 satellites, launch vehicles and other space-related systems, including everything from geosynchronous-earth orbit satellites used in communications networks, low-earth orbit vehicles used for scientific research and information-gathering (also known as spying) and probes used for deep space exploration. If you follow the goings-on of the International Space Station (ISS), you might have heard of the Antares rocket and Cygnus cargo logistics spacecraft, vehicles used by Orbital to ferry supplies to the ISS.

It also does a significant volume of defense-related work, providing booster rockets which power interceptor vehicles designed to destroy hostile missiles launched against the US and its allies, as well as missile defense targets designed to test those systems.

Orbital’s stock has sold off by almost 11 percent over the past month, following a somewhat disappointing second quarter earnings report. While it beat analyst estimates by a nickel with earnings per share of 34 cents, revenues were 5 percent off the same period last year at $318 million, as several satellite contracts were delayed and costs were up slightly. Management also projected that full-year revenue could also come up a bit lighter than previously expected, lowering its forecast from between $1.45 billion to $1.5 billion to between $1.4 billion and $1.425 billion.

While that news clearly spooked the markets, it appears to me that the selloff has been overdone. While revenues will soften a bit this year because of some program delays, Orbital is still a solid growth play.

In the second quarter it locked up $550 million of new business and entered into a deal valued at about $155 million to build four satellites for Avanti Communications of London just this week. That new business, won in just a single quarter, amounts to nearly half of the company’s revenue in 2013, and it has a backlog of nearly $5 billion worth of work. NASA has also committed to continue participating in the ISS program, making it much more likely that Orbital will continue supplying the space station beyond 2016.

Orbital has also announced that it has agreed to a merger-of-equals with Alliant Techsystems (NYSE: ATK) in an all-stock deal that should close in the fourth quarter. While Alliant is perhaps best known as the largest ammunition manufacturer in America, the merger will marry strengths in both commercial and government aerospace operations.

Perhaps the company’s greatest draw though is its free cash flow. Negative just a few years ago, Orbital has become such a lean operator that it grew to $17 million last year and should top $120 million in 2014. At the same time, analysts forecast annual earnings growth of better than 11.5 percent over the next five years largely thanks to growing demand for communications satellites.

Thanks to the recent selloff, Orbital’s shares are currently trading at just 12.1 times forward earnings as compared to the S&P 500’s 17 times. It also has a price-to-earnings-growth ratio – the price-to-earnings ratio divided by its earnings growth – of 0.8, implying that shares are now undervalued.

About to become a force to be reckoned with thanks to the merger, even as it keeps growing in its own right, Orbital Sciences is a great buy under 31.