**The Roots of Science / Platform Expertise**

SG Geodesy is the science that inter-group disciplined for using the measurements on the surface of the Earth and of the air vehicle and spacecraft to study the shape and size of the Earth, planets and satellites, as well as changes to them; accurately determine the position and speed of the points or objects on the Earth’s surface or orbiting the Earth and planets in a particular reference system; and apply that knowledge to a variety of scientific and engineering applications using mathematics, physics, astronomy, and computer science by definition the latest Geodesy given by IAG, the field of a major review of geodesy is divided into 3 parts, namely positioning, determining the field of gravity, and the temporal variation of positioning and gravity field, which is the spatial domain of Earth along with other celestial objects. Every field of study above has a very wide spectrum, from the theoretical to the practical, from the earth to the other celestial bodies, and also includes the land forces, sea, air, and space

Geodetic science would certainly synonymous with positioning, and so did the opposite. The position (point) can be expressed qualitatively and quantitatively. When viewed quantitatively position of a point expressed by the coordinates, both in the space of one, two, three, or four-dimensional (1D, 2D, 3D, 4D).

To ensure consistency and standardization, there needs to be a system in the states coordinate. This system is called the reference coordinate system, or briefly referred to the coordinate system, and the realization is usually called a frame of reference coordinates of the earth’s surface point positions are generally defined in a terrestrial coordinate system (CTS: Conventional Terrestrial System). The zero point of this terrestrial coordinate system can be located at the center of mass of the earth (geocentric coordinate system), and at one point on the earth’s surface (toposentrik coordinate system). While the position of the point in space (satellite positioning, and the heavenly bodies) are usually set in a celestial coordinate system / Inertia systems (CIS: Conventional Inertial System). Survey for positioning of a network on the earth’s surface, can be either terrestrial or extra-terrestrial. In a survey by the method of terrestrial, positioning the points made by observing to the target or object located on the surface of the earth. Meanwhile the survey positioning as an extra-terrestrial, positioning dots performed by making observations or measurements of celestial objects or objects in the sky, such as stars, the moon, and quarsar, and also objects or man-made object that is satellite form.

**DETERMINATION OF HEAVY EARTH FORCE FIELD**

One of the goals of the science of geodesy include determining the shape and size of the earth including determining the Earth’s gravity field in the dimension of time and space. The shape of the earth is approached through several models including ellipsoida which is the ideal form with the assumption that the density (density) homogeneous earth. While it is true in fact, heterogeneous mass density of the earth with the mountains, the mountains, the ocean, basins, plains, and others will make the turn into Geoid ellipsoid. Geoid has an important role in various ways such as for application geodesy, oceanography, and geophysics. Examples for the field of geodesy, namely the use of GPS technology in high determination orthometrik for various practical purposes such as engineering, surveying, and mapping information geoid requires meticulous. In principle geoid (geopotential model) can be derived from gravity data as the main data whose distribution covers the entire surface of the earth. Accuracy a geopotential model is mainly determined by the quality of gravity data, as well as determined by a mathematical formula that is used when lowering the model. Gravity data can be obtained from measurements by terrestrial use gravimeter, from the air with the technique of water-borne gravimetry, and is derived from satellite data (satellite system is geometric such as satellite altimetry (sea area) and the satellite system is dynamic as GRACE and Gocce, and through interpolation for the area that no data-region gayaberatnya.

**MONITORING SYSTEM DYNAMIC EARTH**

In the past people thought the earth is static. Along with the development of science and technology, the paradigm of static earth transformed into a dynamic earth, which is in real terms that the earth is a dynamic system. The dynamic of the Earth has a very wide spectrum, from the scale galactic scale local movements in the earth’s crust. Earth moving together of our galaxy relative to other galaxies. It spins besama our solar systems in our galaxy. Earth’s orbit around the sun along with the other planets. It spins on its rotational axis, and the crust of the Earth also moves (relatively slow) relative to one another. As a result of the movement of the earth’s crust appears mountains, volcanoes, and mountains, as well as lead to the occurrence of volcanic eruptions, earthquakes, landslides, and other natural disasters. One domain of geodesy is the monitoring of the earth system, in this case intended as to the definition of the coordinate system, and the dynamics of the coordinate system. Besides the role of geodesy in monitoring the dynamics of the earth system is to contribute to the monitoring and mitigation of potential natural disasters such as volcanic activities of volcanoes, earthquakes, landslides (landslide), soil degradation (land subsidence), and others.

**Member SG :**

- Dr. Ir. Wedyanto Kuntjoro, M.Sc.
**(Chairman)** - Ir. Bambang Subekti, M.T.
- Ir. Kosasih Prijatna, M.Sc.
- Prof. Dr. Ir. Hasanuddin Z. Abidin, M.Sc.
- Dr. Ir. Agustinus Bambang Setyadji, M.T.
- Ir. Mipi Ananta Kusuma
- Dr. Ir. Dina Aggraeni Sarsito, M.T.
- Dr. Irwan Meilano, S.T., M.Sc.
- Dr.Techn. Dudy Darmawan Wijaya, S.T., M.Sc.
- Heri Andreas, S.T., M.T.
- Drs. Zamzam Akhmad Jamaludin T., M.Si.
- Irwan Gumilar, S.T., M.Si.
- Dr. Ir. Vera Sadarviana, M.T.