The capability of small spacecraft to dock reliably and autonomously would vastly increase the utility of assistive free flyers on the ISS. To this end, spacecraft need an end-effector to grasp and grip objects of a wide variety of shapes and sizes. We propose to develop a universal gripper based on magnetorheological (MR) fluids for use in microgravity environments. MR fluids, which are composite fluids consisting of magnetic grains suspended in a fluid matrix, become jammed (or cease flowing) when a magnetic field is applied. Thus, the motion of any object entrained in the granular fluid is resisted. Traditional universal jamming grippers require the removal of the fluid matrix (typically air) from the control volume in order for the fluid to jam. Using MR fluids simplifies the design and reduces mass/volume/power requirements by removing the need to evacuate (reinflate) the end effector in order to grip (release) the target – instead jamming is triggered by the application of a magnetic field. The MR gripper is likely to be extremely reliable (no moving parts) as well as being applicable to a variety of operational settings. We propose to experimentally vary the MR fluid characteristics to maximize the functionality of the gripper. Additionally, we will mode the dynamics of object insertion in order to define the operational constraints of the device. Finally, we will calculate the mass, power and volume requirements for the most effective device configurations.