Gravity Science Goals for the UAE EMA Mission

The UAE’s Emirates Mission to the Asteroid Belt (EMA) is scheduled to launch later this decade. The mission will rendezvous with the water-rich asteroid (269) Justitia, and along the way will flyby 6 different main belt asteroids. The EMA mission goals combine both scientific investigation on the nature of water-rich asteroids and determining the resource potential present in asteroidal bodies. While all of the asteroid flybys will be too fast to enable precise mass estimates, the rendezvous with Justitia will include estimating its mass, gravity field and internal density distribution as a main scientific goal. The approach to be taken will mimic other asteroid rendezvous missions such as NASA’s NEAR, Dawn and OSIRIS-REx missions. Specifically, a combination of optical navigation images along with radio metric tracking from the Earth during an orbital phase will be combined to determine the asteroid precise spin state, total mass, and gravity field coefficients.

 

Upon arrival at Justitia, the EMA spacecraft will first have a few flybys of the asteroid to determine its overall mass. Following this will be an extended mission phase where it will orbit the asteroid to measure its higher gravity coefficients. After the gravity field is appropriately mapped, the mission will focus on observations of its surface with multi-spectral instrumentation. While the first orbital phase is driven by navigation needs, gravity science will process tracking and optical navigation measurements through all of the orbital phases of the mission in order to produce the highest fidelity gravity field feasible.

 

This talk will introduce the specific challenges that the EMA mission will need to overcome at Justitia. Challenges and opportunities exist for the orbital phase of the mission, as depending on the precise spin state and total mass of the body, a sun synchronous orbit may be feasible and advantageous for the other imaging instruments. A key scientific result will be the bulk density measurement and comparison of the measured gravity field with the overall shape model of the asteroid, enabling constraints on the internal distribution of material in this body. The talk will also review the expected performance based on mission design and current knowledge of Justitia’s likely shape, spin and density range.

 

Funding support for the EMA project was provided by the United Arab Emirates Space Agency and its knowledge partner, the University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics.