Mars 2000 (Sphere) - ESRI:104971

WKT

GEOGCS["Mars_2000_(Sphere)", 
	DATUM["Mars_2000_(Sphere)", 
		SPHEROID["Mars_2000_(Sphere)", 3396190.0, 0.0]], 
	PRIMEM["Reference_Meridian", 0.0], 
	UNIT["Degree", 0.0174532925199433]]

WKT2

GEOGCRS["Mars_2000_(Sphere)", 
	DATUM["Mars_2000_(Sphere)", 
		ELLIPSOID["Mars_2000_(Sphere)", 3396190.0, 0.0]], 
	PRIMEM["Reference_Meridian", 0.0], 
	CS[ellipsoidal, 2], 
	AXIS["Longitude (lon)", east, 
		ORDER[1]], 
	AXIS["Latitude (lat)", north, 
		ORDER[2]], 
	ANGLEUNIT["Degree", 0.0174532925199433], 
	ID["Esri", "104971"]]

Data from @esri/proj-codes

{
  "wkid": 104971,
  "latestWkid": 104971,
  "macro": "PE_GCS_XT_MARS_2000_SPHERE",
  "name": "Mars_2000_(Sphere)",
  "wkt": "GEOGCS[\"Mars_2000_(Sphere)\",DATUM[\"Mars_2000_(Sphere)\",SPHEROID[\"Mars_2000_(Sphere)\",3396190.0,0.0]],PRIMEM[\"Reference_Meridian\",0.0],UNIT[\"Degree\",0.0174532925199433]]",
  "wkt2": "GEOGCRS[\"Mars_2000_(Sphere)\",DATUM[\"Mars_2000_(Sphere)\",ELLIPSOID[\"Mars_2000_(Sphere)\",3396190.0,0.0]],PRIMEM[\"Reference_Meridian\",0.0],CS[ellipsoidal,2],AXIS[\"Longitude (lon)\",east,ORDER[1]],AXIS[\"Latitude (lat)\",north,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433],ID[\"Esri\",\"104971\"]]",
  "description": "Mars 2000 (Sphere)",
  "authority": "Esri",
  "version": "10.5.1",
  "deprecated": "no",
  "areaname": "Body",
  "extent": {
    "slat": -90,
    "nlat": 90,
    "llon": -180,
    "rlon": 180
  }
}