If I look up Mars in the nightsky for one second, can I see photons from perseverance rover? The classical EM theory would say that yes, of course, there is a small EM amplitude wave that comes from the rover which would end up in my retina, at any time interval of the observation.
However I do not know what the answer is, according to deeper theories (quantum field theory?), where light is quantized as photons. If the answer is ''probably not'', can we have an estimate on this probability? What would be the expected time of observation such that the probabilty of a retina to catch at least one photon from perseverance to yield 1/2?
My intuition tells me that the probability is very low, and that an observer would have to wait thousands of years before a single photon from the rover would end on his retina. I base my intuition on the difficulty to measure a single photon coming from a laser on earth pointing towards a mirror on the Moon, where in this case the photon beam is much better oriented than in the case of perseverance, and the proximity is also much greater in the Moon's case.
 A: Ok, I think I have a better answer for you. Imagine a sphere of the photos that are reflected from the perseverance rover expanding out into space. If you can find out the surface area of that expansive sphere, your eye's radius, and the number of photos that pass through the total surface, you can find out how many are hitting your eye.
The closest approach of Mars to earth is 54.6 million km. That is the radius of the sphere. Surface area of a sphere is 4(pi)(R)^2 where R is your radius of the sphere. 54.6 million km to meters is 54600000000 meters, or 5.46E10 meters. 4(pi)(5.46 x 10^10 m)^2 = 3.75E22 m^2.
Assuming the area available for photons to enter your eye is 1 cm^2, then the area in meters is 1E-4 m. The ratio of the area of your eyeball to the surface of the sphere is about 2.67E-27. In other words, 2.67E-27 photons will hit your eyeball per second per 1 photon that is going through that larger sphere.
Next, we need to find out how many photons are reflected by the rover. At local noon on Mars, with Sun directly overhead, the solar irradiance is 590W/m^2 (590 watts per square meter).
I found this thread on Quora to find the number of photons. I just adapted the numbers a little bit.
https://www.quora.com/How-do-you-find-the-no-of-photons-per-second-by-a-lamp-emitting-10-watts-power-and-having-wavelength-550-nanometer
Since 550 nm for wavelength is right in the middle of the spectrum for visible light, lets assume that all of the photons have a wavelength of 550nm.
550 nm photons have 2.26 eV.
eV = 1.6×10−19 joules
3.62x10–19 joules per photon 550nm
590W = 590 joules per second.
590W/(550nm joules per photon)=1.81E21 photons per second at 590W.
If we multiply 1.81E21 photons per second by the top surface area of Perseverance, then we have the number of photons that are coming off of Perseverance per second. The top surface area is about 8 meters squared, so now we have 1.45E22 photons.
If we multiply the total amount of photons emmited by the ratio of photons that will hit your eye to the total surface area of the expanding sphere, we get 0.0000386515608 photons per second. Because you have two eyes, that number is 0.0000773031216 that are entering your eyes per second. After multiplying that number by the ratio of second to minutes (60) and minutes to hours (60) we can conclude that you will see a photon that hit perseverance every 4 hours.
So, in theory, yes, you could have a photon hit your eye if you stare at Mars long enough. But, its certainly not practical. I hope that helps!
