This paper presents the purpose, design and methods of the exploration of Martian Space Environmental Magnetic Field by Yinghuo-1 (YH-1). YH-1 is the first Chinese Martian Space Environment Exploration Orbiter, which would be launched with Russian spacecraft ``Phobos-Grunt'' in October, 2009, and will reach Mars orbit in September, 2010. The main scientific objectives of the YH-1 mission are related with Martian space magnetic field structure and dynamic processes, and a fluxgate magnetometer was considered to be one of the most import payloads in the YH-1 orbiter. The instrument is designed to work in harsh environment around Mars orbit and to collect high resolution data in operational orbit. Two three-component fluxgate type sensors are installed in one boom with separation distance of 45 cm
, and gradiometer mode is used to minimize the remnant field of platform. The boom is located at the tip of the deployable solar panel, and the distance between the center of the spacecraft and the outer sensor is about 3.2 m
. The operation temperature of YH-1 magnetometer sensors is expected in the range -130~+75°C
and the dynamic range is ±256 nT in 16-bit resolution. With a very low noise level below 0.01 nT·Hz-1/2
, this magnetometer can measure three-component magnetic field from DC to 10 Hz. The magnetometer will work together with a Plasma Package onboard this orbiter to complete exploration of Martian space environment. The total mass of this magnetometer package is about 2.5 ,kg, and power consumption is 6.8 W.