Here are some factors that make it tricky:
* Different Missions: Some probes are designed for specific tasks (e.g., flybys, orbiters, landers, rovers). Should they be counted individually or as part of a larger mission?
* Success/Failure: Should failed probes be included?
* Different Countries: Many countries have launched probes, so it's important to consider both national and international missions.
However, we can give you a range:
* Over 100: This is a conservative estimate including probes from all countries and counting successful and failed missions.
* Over 200: This number includes probes from all countries, and possibly counts individual spacecraft within a mission (e.g., the multiple rovers on Mars).
To get a more accurate number, you could consult resources such as:
* NASA's website: They have a comprehensive database of missions.
* Wikipedia: Their "List of artificial objects on the Moon" and "List of artificial objects in orbit around the Earth" may include some probes.
* Other space agency websites: Like ESA, JAXA, Roscosmos, etc.
Ultimately, the number of space probes Earth has had is constantly evolving as new missions are launched and data is collected.
