Calculating the distance between perseverance and zhurong rovers.

calc_perseverance_zhurong_distance.py

import math

MARS_RADIUS = 3389.5 # https://en.wikipedia.org/wiki/Mars


# source https://spacenews.com/chinas-zhurong-mars-rover-lands-safely-in-utopia-planitia/
ZHURONG_LONGITUDE = 110.318
ZHURONG_LATITUDE = 24.748

# source https://www.jpl.nasa.gov/news/press_kits/mars_2020/launch/mission/landing_site/

PERSEVERANCE_LONGITUDE = 77
PERSEVERANCE_LATITUDE = 18


# modified from https://stackoverflow.com/a/4913653
def haversine(lon1, lat1, lon2, lat2, radius):
    """
    Calculate the great circle distance between two points 
    on the earth (specified in decimal degrees)
    """
    # convert decimal degrees to radians 
    lon1, lat1, lon2, lat2 = map(math.radians, [lon1, lat1, lon2, lat2])

    # haversine formula 
    dlon = lon2 - lon1 
    dlat = lat2 - lat1 
    a = math.sin(dlat/2)**2 + math.cos(lat1) * math.cos(lat2) * math.sin(dlon/2)**2
    c = 2 * math.asin(math.sqrt(a)) 
    return c * radius



if __name__=="__main__":
    distance = haversine(ZHURONG_LONGITUDE, ZHURONG_LATITUDE, PERSEVERANCE_LONGITUDE, PERSEVERANCE_LATITUDE, MARS_RADIUS)

    print( f"The distance between the zhurong and the perserverance rowers is {round(distance)} km." )

That lat/lon for Zhurong was the planned landing spot. Actual lat/lon was reported to be 109.7 E, 25.1 N, modified inexplicably on Wikipedia to 109.9. Since then, rover and lander have been imaged by HiRISE, leading to improved lat/lons of rover and lander. I'd not consider those to be 'final' values, but they'll be a lot closer than the 0.1-degree precision values.

Also note that Perseverance is at about 77.4509E, 18.446N. That tool has positions for most hardware that has been on Mars, though it's not caught up on Zhurong yet.

Thank you Bill. It was just a quick sketch to calculate the approximate distance. I used it to show that it is very unlikely that these two robots can ever "visit" each other.

To do that the used precision was more than enough.

That being said thank you very much for the more precise values!