Orbital Sciences Corp. posted first quarter revenues of $228.2 million, up 19 percent from revenues of $192.2 million in the same period a year ago, the company announced April 19. Earnings improved from $8.8 million in the 2006 first quarter to $11.5million in the first three months of 2007.

Orbital credited the revenue increase to a 21 percent gain in the in satellites and space systems segment revenues, driven mainly by work on NASA’s Orion program as well as growth in communications satellites. Launch vehicles segment revenues increased 12 percent due to higher revenues from target vehicles along with expanded activity in the interceptor and space launch vehicle product lines.

Orbital’s firm contract backlog stood at $1.9 billion at the end of March, while total backlog was about $3.7 billion. Orbital raised its outlook for 2007 revenues to between $900 million and $925 million, up from previous estimates of $880 million to $925 million.