Comparison of existing gravity field recovery methods for satellite gravity missions

The goal of challenge 1 is to compare different gravity field recovery methods under controlled conditions, where a well defined set of parameters is used to simulate data. As this is the first MDC, two set of data set are provided: basic and advance.
For the basic MDC1 an Earth's gravity model is used to generate satellite orbits and ranging data for a month of mission time. Basic MDC1 is mainly designed for beginners to start up their own software. Accelerometer and Star camera data are added for the advanced MDC1. Official GRACE data processing centers and groups that already have their own softwares may prefer to start with the advance challenge 1. 

Two main question to be answered within this challenge is:

  • How does the quality of the recovered gravity field differ when the different approaches are used to link the satellite data to the gravitational potential? 
  • What is the difference between the one-step approach and the two-step approach? Which approach is preferred and can be proposed to the community?