The Dulles, Virginia, company's stock price was down more than 15 percent, to $25.75, as of 10:45 a.m. Eastern Time.
Orbital Sciences, along with Space Exploration Technologies, is a key part of NASA's operations now that the Space Shuttle has retired. SpaceX and Boeing are expected to start flying U.S. astronauts to the International Space Station as soon as 2017.
Orbital Sciences carried insurance on the latest mission valued at more than $200 million. The company plans to conduct an internal investigation into what was described as a "catastrophic failure." No one was injured in the incident.
"It is far too early to know the details of what happened," said Orbital executive Frank Culbertson, general manager of its advanced programs group, in a statement. "As we begin to gather information, our primary concern lies with the ongoing safety and security of those involved in our response and recovery operations."
NASA said in a statement that yesterday's accident wouldn't affect its plans to resupply the Space Station from the U.S. These missions are currently done in Kazakhstan under the auspices of Roscosmos, the Russian Federal Space Agency.
"Orbital has demonstrated extraordinary capabilities in its first two missions to the station earlier this year, and we know they can replicate that success," NASA said in a statement. "Launching rockets is an incredibly difficult undertaking, and we learn from each success and each setback."
According to NASA, the crew at the International Space Station isn't in danger of running out of supplies.