Hard to say. No logical scientist would invest that kind of money to find out something like that. In theory, space dust is constantly be obsorbed by earth...though most of it goes to jupiter, the moon and the sun. Barely any actually hits us. --?

The mass of the earth increases by about 7300 TONNES per year due to meteors and debris hitting it. That's 7.3 thousand million grams per year! About 20 tonnes per day. Note: a tonne is 1000kg and is roughly the same weight as a US ton. EDIT: And now I'm turning that answer on its head, because Glenn's question and some more reasearch leads me to belive that around 30,000 tonnes of atmosphere just wander off into space each year. Therefore the Earth is on a diet, rather than a space binge.

1) "I became convinced that the earth must be expanding by the ever increasing length of scheduled flights between the same two cities. For example, in the early 1980's a flight from Chicago to Toronto, gate to gate, was 58 minutes long with a fairly good on time record. Currently, the flight between Chicago and Toronto is about an hour and 30 minutes gate to gate with a similar on-time record. A lot of airlines are still flying planes that are 30 years old and should fly at the roughly the same speed (with newer planes capable of flying faster). Therefore, the only logical conclusion is that the distance between cities is increasing as the earth expands, which is why its taking longer to fly between cities. However, a more detailed analysis may yield data that cities farther apart originally haven't moved as far apart as cities that were closer to each other. For instance, the flight from LA and Hong Kong might be only 45 minutes longer, whereas flights from New York to Boston are 20-30 minutes longer than they were 20-30 years ago. This discrepency might be attributed to plate techtonics and continental drift." Source and further information: "Expanding Earth Theory" http://dilbertblog.typepad.com/the_dilbert_blog/2008/03/expanding-earth.html Further information: http://en.wikipedia.org/wiki/Expanding_earth_theory http://en.wikipedia.org/wiki/Growing_Earth_Theory 2) "The mass of the earth is nearly constant. Some light materials in the atmosphere are lost (hydrogen, helium), but we gain dust from micrometeorite impacts." Source and further information: http://www.newton.dep.anl.gov/askasci/gen99/gen99920.htm 3) "There are ways that the mass of the Earth can change. For instance, the lunar rover was left on the Moon by the Apollo astronauts, so that mass is no longer part of the Earth. Meteorites that crash into our planet, or even burn up in our atmosphere, can contribute some small mass to the planet. One of the most famous equations in physics, E=mc^2, actually tells us another way for total mass to change. Albert Einstein put forth the idea that matter and energy are just different forms of the same thing. Matter can be changed to energy, and vice versa. It doesn't happen much on Earth, but the massive amount of energy coming out of our Sun actually represents a gradual decrease in the Sun's mass." Source and further information: http://www.ccmr.cornell.edu/education/ask/index.html?quid=733