Memes

I'm pretty sure you couldn't see something this small at that distance with current telescopes unless it emitted some pretty bright light. Like say, if it had a very bright tail much bigger than itself (not possible in this case, too small, you only see tails on much bigger comets) or if it entered an atmosphere at high speed and burned up. Problem is Mars barely has any atmosphere to speak of...i mean it has one but it's a hundred times less dense than Earth's.

Another way of detecting fairly small objects in space is by observing occlusion of light sources behind them, since you can detect fairly tiny decreases in the intensity of a light source when something passes in front of it even if that object itself is too small to be seen. It's how we detect exoplanets. But i don't think that is applicable in this case, and even this method has limits.

Yet another method by which you could detect and measure the mass of things that can't be visibly seen is by observing gravitational pull on other nearby objects that are visible. But again this is most likely not applicable here because the size is too small. On anything asteroid sized you generally measure mass via spectroscopy (for which you need to be able to see the thing), analyzing chemical composition and inferring mass from density and observable size.

At least this is what i remember from my astrophysics classes back in uni. It's been over a decade though so things have advanced since then, i could be out of date on my knowledge...