USA-242

USA-242, also known as GPS IIF-4, GPS IIF SV-5, Navstar-68 and Vega,^[3] is an American navigation satellite which was launched on 15 May 2013 and became operational on 21 June 2013.^[4] The fourth Block IIF GPS satellite, it forms part of the Global Positioning System.

USA-242

Artist's impression of a GPS IIF satellite
Mission type	Navigation
Operator	US Air Force
COSPAR ID	2013-023A
SATCAT no.	39166
Mission duration	12 years (planned)
Spacecraft properties
Spacecraft	GPS SVN-66 (IIF-4)
Spacecraft type	GPS Block IIF
Manufacturer	Boeing
Launch mass	1,630 kilograms (3,590 lb)[1]
Start of mission
Launch date	15 May 2013, 21:38 (2013-05-15UTC21:38Z) UTC
Rocket	Atlas V 401, AV-039
Launch site	Cape Canaveral SLC-41
Contractor	ULA
Orbital parameters
Reference system	Geocentric
Regime	Medium Earth (Semi-synchronous)
Perigee altitude	20,459 kilometers (12,713 mi)[2]
Apogee altitude	20,459 kilometers (12,713 mi)[2]
Inclination	55 degrees[2]
Period	12 hours
Epoch	Target

USA-242 is a 1,630-kilogram (3,590 lb) spacecraft, built by Boeing with a design life of 15 years.^[1] It operates from a semi-synchronous medium Earth orbit, at an altitude of 20,459 kilometers (12,713 mi) an inclination of 55 degrees,^[2] in slot 5 of plane C of the GPS constellation.^[5] The new satellite was originally intended to replace the seventeen-year-old USA-117 satellite,^[6] but currently both USA-117 (SVN-33) and USA-242 (SVN-66) are in active use.^[7] USA-242 broadcasts its navigation signals using the PRN-27 signal modulation.

United Launch Alliance conducted the launch of GPS IIF-4, using an Atlas V 401 carrier rocket. Launch took place from Space Launch Complex 41 at the Cape Canaveral Air Force Station, with liftoff occurring at 21:38 UTC on 15 May 2013, the beginning of an 18-minute launch window. The launch marked the first time since 1985 that a GPS satellite had launched on an Atlas rocket, or indeed any rocket other than a Delta.^[6]