We present RadioAstron Space VLBI imaging observations of the BL Lac object S5 0716 + 71 made on January 3–4 2015 at a frequency of 22 GHz ( wavelength \lambda = 1.3 cm ) .
The observations were made in the framework of the AGN Polarization Key Science Program .
The source was detected on projected space-ground baselines up to 70 833 km ( 5.6 Earth diameters ) for both , parallel hand and cross-hand interferometric visibilities .
We have used these detections to obtain a full-polarimetric image of the blazar at an unprecedented angular resolution of 24 \mu as , the highest for this source to date .
This enabled us to estimate the size of the radio core to be < 12 \times 5 ~ { } \mu as and to reveal a complex structure and a significant curvature of the blazar jet in the inner 100 \mu as , which is an indication that the jet viewing angle lies inside the opening angle of the jet conical outflow .
Fairly highly ( 15 % ) linearly polarized emission is detected in a jet region of 19 \mu as in size , located 58 \mu as downstream from the core .
The highest brightness temperature in the source frame is estimated to be > 2.2 \times 10 ^ { 13 } K for the blazar core .
This implies that the inverse Compton limit must be violated in the rest frame of the source , even for the largest Doppler factor \delta \thicksim 25 reported for 0716 + 714 .