Artist conception of QuikSCAT |
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| Operator | JPL, NASA |
|---|---|
| Major contractors | Ball Aerospace & Technologies Corp. |
| Mission type | Earth observation |
| Satellite of | Earth |
| Launch date | June 19, 1999 on a Titan 23G |
| Launch site | Vandenberg Air Force Base |
| Mission duration | 2–3 years (used for 10 years) |
| Homepage | winds.jpl.nasa.gov/missions/quikscat/ NASA.gov |
| Mass | 971 kg (launch) |
| Orbital elements | |
| Semimajor axis | 7180.8 km |
| Eccentricity | 0.00014 |
| Inclination | 98.6 degrees |
| Orbital period | 100.93 minutes |
| Right ascension of the ascending node : 178.47 degrees, Argument of perigee : 47.4 degrees Instruments: SeaWinds - microwave radar that measures near-surface wind speed and direction |
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The QuikSCAT (Quick Scatterometer) is an earth-observing satellite that provided estimates of wind speed and direction over the oceans to National Oceanic and Atmospheric Administration and others. This "quick recovery" mission intended to replace the NASA Scatterometer (NSCAT), which failed in June 1997. The satellite launched on 19 June 1999 with an intended mission of two or three years. QuikSCAT, however, continued to operate for a decade and stopped working circa 23 November 2009, when the bearings in the motor of the spinning antenna failed.
When QuikSCAT operated normally and the antenna rotated, the spacecraft collected information on winds in strips 1800 kilometers wide on a daily basis. The QuikSCAT scatterometer still continues to provide useful remote sensing data over specific regions and giving scientists a way to test the accuracy of other space-based scatterometers.[1] QuikSCAT operates in a sun-synchronous orbit (low-earth orbit).
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In 1996, the NASA Scatterometer (NSCAT) was launched aboard the Japanese Advanced Earth Observing Satellite. This satellite was designed to record surface winds over water across the world for several years. However, an unexpected failure in 1997 led to an early termination of the NSCAT project. Following this briefly successful mission, NASA began constructing a new satellite to replace the failed one. They planned to build it and have it prepared for launch as soon as possible to limit the gap in data between the two satellites.[2] In just 12 months, the Quick Scatterometer (QuikSCAT) satellite was constructed and ready to be launched, faster than any other NASA mission since the 1950s.[3]
The QuikSCAT project was originally budgeted at $93 million, including the physical satellite, the launch rocket, and ongoing support for its science mission.[4] A series of rocket failures in November 1998 grounded the Titan (rocket family) launcher fleet, delayed the launch of QuickScat, and added $5 million to this initial cost.[4]
A new instrument, the SeaWinds scatterometer, was attached to the satellite. The SeaWinds instrument, a specialized microwave radar system, measured both the speed and direction of winds near the ocean surface. It used two radars and a spinning antenna to record data across nine-tenths of the oceans of the world in a single day. It recorded roughly four hundred thousand wind measurements daily, each covering an area 1,800 kilometers (1,100 mi) in width.[3] Jet Propulsion Laboratory and the NSCAT team jointly managed the project of construction of the satellite at the Goddard Space Flight Center. Ball Aerospace & Technologies Corp. supplied the materials to construct the satellite.
In light of the record-setting construction time, engineers who worked on the project were given the American Electronics Achievement Award. This was only achieved due to the new type of contract made specifically for this satellite. Instead of the usual year given to select a contract and initiate development, it was constrained to one month.[5]
The newly constructed satellite was set to launch on a Titan II rocket from Vandenberg Air Force Base in California. The rocket lifted off at 7:15 pm PDT on 19 June 1999. Roughly two minutes and thirty seconds after launch, the first engine was shut down and the second was engaged as it moved over the Baja California Peninsula. A minute later, the nose cone, at the top of the rocket, separated into two parts. Sixteen seconds later, the rocket was re-oriented to protect the satellite from the sun. For the next 48 minutes, the two crafts flew over Antarctica and later over Madagascar, where the rocket reached its desired altitude of 500 mi (800 km).[6]
At 59 minutes after launch, the satellite separated from the rocket and was pushed into its circular orbit around Earth. Shortly after, the solar arrays were deployed and connection was established with the satellite at 8:32 pm PDT with a tracking station in Norway. For the next two weeks, the shuttle used bursts from its engine to fine-tune its location and correct its course to the desired motion. Eighteen days after take-off, the scatterometer was turned on and a team of 12 personnel made detailed reviews of function of QuikSCAT. A month after entering orbit, the team completed the checks, and QuikSCAT began circling the globe constantly. NASA planned for the satellite to operate for two years.[6]
Not long after being activated, the data collected by the satellite proved to be very useful in forecasting tropical cyclones. The scatterometer's ability to record wind speeds at the surface allows meteorologists to determine whether a low pressure area is forming and enhance the ability to predict sudden changes in structure and strength. QuikSCAT continuously provided data from across the globe without error, "The data are looking great, better even than we expected."[7] The first tropical cyclone captured by the SeaWinds instrument was Typhoon Olga in the western Pacific basin. The system was constantly monitored by the satellite from its generation on July 28 to its demise in early August. Members of the QuikSCAT project believed that the satellite would eventually have a major role in climatological studies, weather prediction and oceanographic research.[7]
During 2000, a public statement about the improvement of weather forecasting was attributed to the data provided by QuikSCAT. During the year, the satellite began recording wind directions, allowing forecasters to better predict when a storm could develop. Data was also provided in real-time for areas previously without recording devices, filling the information gaps across the world.[8]
Other uses of the data include resource assessment for the emerging offshore wind energy industry. WindScan has taken advantage of satellite data specifically for this purpose.
In 2007, Bill Proenza, the head of the National Hurricane Center at the time, stated in a public message that the loss of the QuikSCAT satellite would greatly harm the quality of hurricane forecasts.[9] This followed the loss of the main power source, leading to the satellite running on a backup generator.[10] He claimed that three-day forecasts would be roughly 16% less accurate following the loss of QuikSCAT.[11] However, this was found to be an exaggeration, during his controversial time at the center, which eventually led to him being removed from his position. Although the satellite aids in hurricane intensity, it does not do so exclusively and other satellites in orbit, with similar equipment, record the same information.[9]
During mid-2009, the QuikSCAT project began noticing a gradual deterioration in the bearings that allow the antenna that provides real-time data. The bearings produced more friction than in the past nine years the satellite was in orbit. This friction slowed the rate the antenna spun, leading to gaps in data recorded by QuikSCAT across the world. This culimated in the antenna's failure on November 23, 2009.[13] Upon failing, it was announced that the satellite was likely at the end of its mission and would no longer be used.[12] The sensor on the satellite was confirmed to have failed around 0700 UTC. The loss only affected the real-time scanning equipment; the long-term data collection remained intact and operational.[11] According to NASA, the failure resulted from the age of the satellite. The mechanism that seized was designed to last only five years; however, it remained operational for roughly ten years, twice its expected use. On November 24, NASA managers began to assess how extensively affected the satellite was and if it was possible to restart the spinning antenna. Contigency plans for what to do in the event of QuikSCAT's failure were also reviewed.[13]
Replacement of this satellite remains a topic of debate. Although NHC forecasters occasionally cite the data provided by QuikSCAT, some do not feel that the value of the data warrants the expenditure that would be necessary for replacement of the satellite with a similar instrument, but rather advocate development of a more advanced satellite.
A joint project for creating a new satellite with the next generation of equipment has been announced by NASA and the NHC. The new satellite is scheduled to be operational in 2015, at which time it will be put in orbit around Earth.[9]
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