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Sounding Rocket 9 Science Experiment - Space Ionosphere Irregularity Research

NSPO 2014/03/27

The Sounding Rocket 9 (SR9) of the National Space Organization (NSPO), National Applied Research Laboratory, was successfully launched at 21:34 on March 26 from the Gio-pern Base in Pintung County and completed the ionosphere dynamics measurements over the southern sky of Taiwan.

At six seconds after launch, the first stage of SR9 completed its combustion and separated from the rocket. At the 12 second mark, the second stage was ignited and burned out at 42 second. By the rocket momentum, it continued its ascend and performed the nose-cone faring separation at 58.2 second and 82 km altitude to commence the plasma and electron density measurements with an Impedance Probe and a Plasma Sensor system. At the 270 second mark, the rocket reached its maximum altitude of 286 km then descend and fell into the ocean at the 520 second mark after completing the science experiment.

A main feature of this mission includes the integration of a ground system that composed of a 30 MHz radar array with a Tri-Band Beacon (TBB) receiver (Note 1) of the FORMOSAT-3 Satellite and a 52 MHz radar array installed in the Gio-pern Base and at the Taimali Base in Taitung, respectively. This ground system was used to detect the sign of ionosphere irregularity (Note 2), which provided a good reference for the best time to launch the rocket.

The ionosphere irregularity science instruments onboard SR9 consist of the Impedance Probe and the Plasma Seneor system that includes a Retarding Potential Analyzer (RPA), an Ion Drift Meter (IDM) and a Planar Langmuir Probe (PLP). These instruments and the ground radar system are developed by the National Central University (NCU) team.

Ionosphere Irregularity affects GPS Reception and Satellite Communication

Taiwan is located in the low-latitude region closer to the Equator, which is affected by the Equatorial Plasma Plume Effects (Note 3) and causes relatively active ionosphere activity and forming the Ionosphere Equatorial Anomaly Region (Note 4). In this region with especially high plasma density, its disturbance may affect GPS users and satellite communications with civil and military implications. The SR9 mission is a continuation of the SR5 and SR7 missions with improved plasma instruments and ground radar systems for continuing the study on the cause and origin of the ionosphere irregularity. The goals of this experiment include:

  1. Scientific Study: measuring key plasma parameters in the ionosphere, which not only reveals insights of the ionosphere plasma distributions but also allows the study and unlocks the mystery of the cause of ionosphere irregularity through correlating data from the ground radar and the science instruments.
  2. Improving Satellite Communication Quality: measuring ionosphere irregularity jointly with the SR9 instruments and the TBB receiver for the FORMOSAT-3 Satellite, which tests the VHF/UHF beacon reception and assists improving the communication quality of satellites.
  3. Ionosphere Data Validation of FORMOSAT-3: the TBB payload onboard FORMOSAT-3 is used to measure the electron density distributions in the ionosphere. Ground radars have been used in the past to validate the reliability of the FORMOSAT-3 data. The Impedance Probe on board SR9 is used to measure the ionosphere electron density profile accurately, which can be used to validate and understand the measurement accuracy of the FORMOSAT-3 ionosphere data.
  4. FORMOSAT-5 Science Payload Flight Test: besides the space environment test validations, sounding rocket flight tests are also essential in developing science payloads for satellites. The Advanced Ionosphere Instrument science payload developed with collaborated efforts between NSPO and NCU has been flight tested onboard SR9. This science payload performance validation method using sounding rocket flight test platform is unprecedented and a significant step for the domestic development teams for our future satellite programs.

Promoting Space Science Education

In addition to scientific study and validation tests, the NCU SR9 team has also invited 42 students from 8 senior-high schools (Tayuan High School, Neli High School, Chungli High School, Pincheng High School, Yuonfung High School, Yuda High School, Fudan High School, Sosan High School) in the Taoyuan County to join the sounding rocket science payload project for the promotion and rooting of space science education for domestic high schools.

As planned based on the SR9 program schedule, NCU began offering more than six classes (36 hours in 12 weeks) to these high school students since September 2013 to cover knowledge related to sounding rocket experiments including space science fundamental, the Earth environment, ionosphere, payload fabrication and testing, basic radar theory, antenna pattern simulation, assembly and testing, etc. These courses allow the students hands-on participation in the sounding rocket experiment.

This NCU class concluded on December 31, 2013 with 28 out of 35 selected for their excellent performance. These selected students with 11 accompanying teachers were then invited to participate in the launch campaign of SR9 to let them experience the exciting launch of the rocket. The students were inspired and motivated through this space science education and rocket launch activity, which will help the future educational development.


Note 1: FORMOSAT-3 Tir-Band Beacon (TBB) Receiver: the Tir-Band Beacon instrument onboard the FORMOSAT-3 satellite, launched in April 2006, transmits radio signals in 3-frequency bands (150, 140 and 1067 MHz) to the ground TBB receiving stations for estimating the electron density distributions in the 90~700 km altitude range.

Note 2: Ionosphere Irregularity: is a non-uniform structure of plasma distribution in the ionosphere. It appears in the 80~280 km altitudes with size scale between a few cm to several thousands km.

Note 3: Equatorial Plasma Plume Effects: during day time around the magnetic equator, the ionosphere plasma is energized due to the interactions between the high-altitude electric and magnetic fields, resulting in a plume spreading in the upward, northward and southward directions.

Note 4: Equatorial Anomaly Region: the energized plasma due to the Equatorial Plasma Plume Effects is tugged by the Earth gravity and causing it to accumulate in huge amount in the region between 10X~15Xmagnetic latitudes (Taiwan is located between the 13X~16X latitude) and 300~350 km altitudes. This region represents the highest concentrations in plasma particles is call the Equatorial Anomaly Region.