CYGNSS readied for flight on wings of Pegasus
CAPE CANAVERAL, Fla — NASA’s Cyclone Global Navigation Satellite System (CYGNSS) is being prepared for a launch currently set to take place late next year (2016). CYGNSS will be used to better predict hurricanes and, in so doing, help to prevent tragedies like Hurricane Katrina. With the satellite currently undergoing construction in Texas, SpaceFlight Insider spoke with the company selected to launch CYGNSS about what is required to get the eight microsatellites aloft.
An Orbital ATK Pegasus XL rocket will use its distinct air-delivery method to payloads to orbit. Whereas most launch vehicles lift off from the active pads at Cape Canaveral, the Pegasus XL will not. It will launch after being dropped from a jet aircraft. Something that has not occurred from Cape Canaveral since the flight of NASA’s Galaxy Evolution Explorer (GALEX) spacecraft on April 24, 2003.
The Lockheed Martin L-1011 Tristar, a medium-to-long range jet aircraft, has the capability of carrying about 400 passengers and is the vehicle tasked with sending CYGNSS on the first of its journey. In the case of this particular L-1011, there’s only one passenger of note – the one that rides slung under the aircraft’s belly.
The L-1011 Tristar has an approximate range of about 4,000 nautical miles (7,410 km), and it is granted this by the two Rolls-Royce RB211 engines that are affixed to the aircraft and a third RB211 that is a component of the aircraft’s tail and fuselage.
If everything goes according to plan next year, CYGNSS should enter service in 2017 – just in time for the Atlantic hurricane season that year.
On August 29, 2005, Hurricane Katrina made landfall – it did so as a Category 3 hurricane on the Saffir-Simpson scale. This meant it had sustained wind speeds estimated to be between 100 to 140 miles per hour – and it measured 400 miles across.
CYGNSS is making progress toward its upcoming flight, having completed two NASA reviews this summer. With these milestones now behind it, the eight microsatellites that comprise the mission are ready for integration, testing. and launch.
“These reviews were a major milestone for CYGNSS, marking the end of the detailed design and planning stages of the mission and the beginning of flight hardware assembly,” said Chris Ruf, CYGNSS’ principal investigator. “We are now in the last phase of the mission prior to launch and the beginning of a new era in hurricane observations.”
It is hoped CYGNSS will provide improved hurricane-prediction capabilities. The spacecraft is designed to monitor winds located on the ocean’s surface – near the eyewall of hurricanes and other cyclones throughout their development and conclusion.
CYGNSS will work with the Global Positioning System; this relationship will allow for better predictions of wind speeds. According to a release issued by NASA, whereas a single satellite produces an image of a storm every few days, the combined CYGNSS and GPS system will produce an image once every few hours.
It is hoped that this fleet will assist hurricane forecasters as well as the communities that depend on their predictions in the U.S. The spacecraft will be placed by the Pegasus XL into low-Earth orbit (LEO) where the satellites will pass over the same region of the Earth about once every 12 minutes.
The first of the eight microsatellites began undergoing assembly about a week ago on Aug. 14, construction of the remaining seven will take place over the course of the next few weeks.
Each of the tiny spacecraft measures about 20-by-25-by-11 inches and will weigh in at about 64 lbs (29 kg) each. With their solar array fully deployed, each of the spacecraft has a “wingspan” of some five and a half feet (1.7 meters).
If everything continues to proceed as planned, the satellites will be stacked in preparation for testing in early 2016.
On the day of launch, Orbital ATK’s L-1011 Tristar will ferry the Pegasus XL and its CYGNSS payload aloft will ascend to its drop altitude of some 39,000 ft, traveling at a velocity of approximately 797 ft/sec. Once it has reached these prerequisites, and the aircraft is in the pre-determined area required for the launch of the Pegasus, the crew on board the L-1011 will serve as “Mission Control” when releasing the Pegasus XL.
Five seconds after the booster and its precious cargo are free of the L-1011, Pegasus’ first stage rocket motor will be ignited. For about one minute and 13 seconds, the booster will be in the powered ascent phase of the mission. The booster/payload duo should reach an altitude of 33 miles (53 kilometers) and achieve a velocity of 8,360 ft/sec (5700 MPH).
Completion of the first stage burn should be followed by a roughly 16-second “coast” stage – at which point the second stage’s rocket motor will be ignited. Halfway through the second stage’s powered flight, the payload fairing, which will have shielded CYGNSS through the remaining part of Earth’s atmosphere, will be jettisoned.
The second stage motor should then activate, burning for about 168 seconds. After the completion of the burn, the vehicle should reach an altitude of some 108 miles (174 km). If things go as planned – the vehicle will have reached speeds of 17,730 ft/sec (12,100 MPH).
Another four-minute coast phase should occur around this time – setting the scene for the third and final stage’s activation.
At some 396 seconds into the mission, the third stage’s rocket motor will ignite. The final burn of this motor should last for about one minute and 10 seconds. This should see CYGNSS placed into a circular 317-mile (510 km) altitude orbit with an inclination of 35 degrees to the Equator.
After the final burn, the Pegasus XL will reorient itself to place CYGNSS spacecraft at the proper separation attitude.
Five minutes after the completion of the third stage burn, four CYGNSS paired-deployment events should get under way. At 30 second intervals, the three subsequent paired-deployment events will be ordered to take place. This follows the first deployment. When all is said and done, CYGNSS should be placed into the proper orbit and the eight microsatellites will be deployed.
Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology, Space.com, The Mars Society and Universe Today.