  A new ambitwistor string is constructed based on a ten-dimensional
supertwistor model for the massless superparticle. Although covariant
quantization is complicated by reducibility issues, a light-cone gauge analysis
can be easily performed. We show that with this analysis, this supertwistor
ambitwistor string is equivalent to the RNS ambitwistor string in light-cone
gauge. In order to make the comparison, we develop the light-cone gauge
analysis of the RNS ambitwistor string which has some novel features in terms
of its expression of the scattering equations through interaction point
operators.
