The Jetson TX2 does not have NTSC (analog) camera inputs directly. It only supports CSI/MIPI cameras and GMSL cameras, and even there, it only supports certain cameras because a special driver from the vendor is needed for each camera sensor chip.
You can perhaps use a USB NTSC capture dongle to capture the camera image, if it has non-binary drivers for Linux (because the aarch64 kernel of the Jetson isn’t commonly supported by binary drivers.)
Or you can get another camera or set of cameras and adapter board. Might be cheapest and simplest.
(For a while I thought perhaps Auvidea has a converter from NTSC to CSI, but it turns out they only have converters from HDMI or HD-SDI.)