CYGNSS, short for Cyclone Global Navigation Satellite System, is now scheduled to launch on Thursday, December 15; an hour-long launch window begins at 8:26am ET.
Known as CYGNSS for short, this mission brings 8 small satellites to low-Earth orbit to make accurate measurements of ocean surface winds in and near the eye of the storm throughout the life-cycle of tropical cyclones, typhoons, and hurricanes. And unlike recent launches at NASA’s Kennedy Space Center, such as the recent GOES-R Weather Satellite launch by United Launch Alliance, these satellites are being sent to their orbit by a rocket deployed from an L-1011 jet aircraft. A Pegasus XL rocket will launch from the Orbital ATK Stargazer L-1011 aircraft after it leaves the Cape Canaveral Air Force Station in Florida.
Two launch attempts were made on Monday December 12 but failed when a hydraulic system responsible for releasing the Pegasus rocket from the L-1011 failed to work properly. Another attempt slated for the morning of December 14 was postponed after a software issue became known. An issue with flight parameter data used by spacecraft software was discovered during routine testing on Tuesday, December 13 but has since been resolved.
Pegasus is a winged, three-stage solid propellant rocket built by Orbital ATK that can launch a satellite into low earth orbit. After takeoff, the aircraft flies to about 39,000 feet over the ocean and releases the rocket. After a five-second free fall in a horizontal position, the Pegasus first stage ignites. The aerodynamic lift, generated by the rocket’s triangle-shaped wing, delivers the payload into orbit in about 13 minutes.
CYGNSS will be the first to probe the inner core of hurricanes in greater detail to better understand their rapid intensification with the goal is to improve hurricane intensity forecasts. Once in orbit, CYGNSS’s micro-satellite observatories will receive direct and reflected signals from Global Positioning System (GPS) satellites. The direct signals pinpoint CYGNSS observatory positions, while the reflected signals respond to ocean surface roughness, from which wind speed is retrieved.
“This mission will help us get a better idea of the intensity of tropical cyclones,” said Frank Peri, director of the Earth Systems Science Program Office (ESSPO), based at NASA’s Langley Research Center in Hampton, Virginia.
Typically, measuring wind speed over the oceans from space uses a technique called scatterometry. A radar instrument aboard a satellite sends a signal to the ground, and measures the signal strength reflected back to it. Building both sending and receiving capabilities into a single instrument, however, is more expensive than the method being used on CYGNSS. The CYGNSS satellites will only receive signals broadcast to them from GPS satellites already orbiting the Earth and the reflection of the same satellite’s signal reflected from the earth. The CYGNSS satellites themselves will not broadcast. And according to Chris Ruf of the University of Michigan and the mission’s principal investigator, that will result in significant cost savings.
“This sampling strategy will overcome the limitations of a previous single, wide-swath approach,” said Ruf.
Another advantage – the CYGNSS orbit is designed to measure only in the tropics, where hurricanes are most often found. Traditional polar-orbiting weather satellites measure the whole globe because they are trying to capture all types of data. The focus on tropical activity means the CYGNSS instruments will be able to gather that much more useful data on weather systems exclusively found in the tropics.
This data will be shared with NOAA and used to help emergency managers make decisions regarding extreme weather planning.
CYGNSS is funded through NASA’s ESSPO and developed by the University of Michigan.