Orbital Sciences Corp. announced April 28 that its board of directors has authorized the company to repurchase up to $50 million of its outstanding securities throughout the next 12 months. The repurchases could include shares of Orbital’s common stock, its senior notes, its stock warrants or any combination of the three securities.

The following outstanding securities are subject to the repurchase program: 55.2 million shares of common stock, $126 million of 9 percent senior notes due 2011, and warrants to purchase about 7.3 million shares of common stock with an exercise price of $3.86 that expire Aug. 31.

The board’s authorization replaces a previous 12-month, $50 million securities repurchase program that expired in April. Under that program, Orbital repurchased a total of 4 million common shares, or about 6 percent of its basic outstanding shares, for $46.1 million — an average of about $11.66 per share.