STSat-2B, or Science and Technology Satellite-2B, was a South Korean

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

which was lost in the failure of the second flight of the

Naro-1 Naro-1 ( ko, 나로호), previously designated the Korea Space Launch Vehicle or KSLV (also KSLV-1), was South Korea's first carrier rocket, and the first South Korean launch vehicle to achieve Earth orbit. On January 30, 2013, the third Naro-1 ...

launch vehicle A launch vehicle or carrier rocket is a rocket designed to carry a payload (spacecraft or satellites) from the Earth's surface to outer space. Most launch vehicles operate from a launch pad, launch pads, supported by a missile launch contro ...

. It was to have been operated by the

Korea Aerospace Research Institute The Korea Aerospace Research Institute (KARI), established in 1989, is the aeronautics and space agency of South Korea. Its main laboratories are located in Daejeon, in the Daedeok Science Town. KARI's vision is to continue building upon indig ...

(KARI), and was intended to demonstrate

technology Technology is the application of knowledge to reach practical goals in a specifiable and reproducible way. The word ''technology'' may also mean the product of such an endeavor. The use of technology is widely prevalent in medicine, science, ...

for future spacecraft. The satellite had a mass of , and was expected to operate for at least two years. STSat-2B was originally intended to operate alongside a second spacecraft, STSat-2A; however STSat-2A was lost in 2009 after the payload fairing of its carrier rocket failed to separate, leaving the rocket unable to achieve orbit.

Instruments

The primary instrument aboard STSat-2B was the Dual-channel Radiometer for Earth and Atmosphere Monitoring, or DREAM, which would have measured the

brightness temperature Brightness temperature or radiance temperature is the temperature at which a black body in thermal equilibrium with its surroundings would have to be in order to duplicate the observed intensity of a grey body object at a frequency \nu. This con ...

of the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

at 23.8

GHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...

and 37 GHz.Dual-channel radiometers for Earth and atmosphere monitoring (DREAM) on micro satellite STSat-2
/ref> The secondary payload, the Laser Retroreflector Array (LRA) was to have been used for the

Satellite laser ranging In satellite laser ranging (SLR) a global network of observation stations measures the round trip time of flight of ultrashort pulses of light to satellites equipped with retroreflectors. This provides instantaneous range measurements of milli ...

experiment, which was intended to determine the parameters of the satellite's orbit with a greater degree of precision. Data collected by the secondary payload would have been used to calibrate DREAM, to conduct

geodetic Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivale ...

research, and to evaluate the performance of the launch vehicle. Due to lower manufacturing tolerance, the retroreflectors on STSat-2B would have provided greater precision than those intended on STSat-2A. A series of technological experiments were also to have been conducted; investigating

attitude control Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle ...

systems, and testing

pulsed plasma thruster A pulsed plasma thruster (PPT), also known as a plasma jet engine, is a form of electric spacecraft propulsion. PPTs are generally considered the simplest form of electric spacecraft propulsion and were the first form of electric propulsion to be ...

star tracker A star tracker is an optical device that measures the positions of stars using photocells or a camera. As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may ...

s, a

Sun sensor A sun sensor is a navigational instrument used by spacecraft to detect the position of the sun. Sun sensors are used for attitude control, solar array pointing, gyro updating, and fail-safe recovery. In addition to spacecraft, sun sensors fin ...

, as well as an experimental onboard computer, and data relay at rates of up to 10

megabits per second In telecommunications, data-transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are multi ...

Launch

STSat-2B was launched by a Naro-1 launch vehicle, flying from the

Naro Space Center , image = Naro Space Center, 2021.jpg , caption = , LID = , type = Spaceport , owner = Government of South Korea , operator ...

. The launch was the second flight of the Naro-1, which consisted of a modified

Angara The Angara ( Buryat and mn, Ангар, ''Angar'', "Cleft"; russian: Ангара́, ''Angará'') is a major river in Siberia, which traces a course through Russia's Irkutsk Oblast and Krasnoyarsk Krai. It drains out of Lake Baikal and is ...

first stage manufactured by

Khrunichev The Khrunichev State Research and Production Space Center (''Государственный космический научно-производственный центр (ГКНПЦ) имени М. В. Хру́ничева'' in Russian) is ...

, and a South Korean solid-fuelled upper stage. The previous Naro-1 launch was that of STSat-2A, which occurred in August 2009 and ended in failure. The launch was initially scheduled to occur on 9 June 2010, during a two-hour

launch window In the context of spaceflight, launch period is the collection of days and launch window is the time period on a given day during which a particular rocket must be launched in order to reach its intended target. If the rocket is not launched wit ...

opening at 07:30 UTC (16:30 local time). Further launch attempts were available at the same time each day until 19 June 2010. The launch attempt on 9 June 2010 was scrubbed after the launch pad's fire suppression system activated for no apparent reason. Following the scrub, the launch was rescheduled for the next day, and took place at 08:01 UTC (17:01 local time) on 10 June 2010. During the first stage burn, around 137 seconds into the flight, contact with the rocket was lost. South Korean science minister Ahn Byung-man later told reporters that the rocket was believed to have exploded. If the launch had been successful, STSat-2B would have been deployed into an orbit with a

perigee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

of , an

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

of , and around 80.0° of

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

References

{{Orbital launches in 2010 Spacecraft launched in 2010 Satellite launch failures Earth observation satellites Satellites of South Korea