Depends on your mass and initial altitude. LEO? yes, probably. 10,000 mi altitude? No, not so much. 23,000? Certainly not. Keep in mind that orbital velocity drops the higher you are, and that gravitational attraction is less the higher you are, so once you drop below orbital velocity you accelerated due to gravity less the higher you are. <br /><br />GEO orbital velocity is about 3 km/s, so, adding in delta v you gain on the way down, you can drop your velocity to zero while still above the atmosphere, and just drop in, however, paradoxically, if done conventionally, the more you retrofire, you continue to drop to lower orbit and accelerate while doing so, until you are in LEO at 17,000+ mph. There is a point, though, between microthrusting and megathrusting, where you can wind up where the poster wants to be. <br /><br />Essentially you want to be able to accelerate with your retrofire engines at 1-5% above whatever the local rate of gravitational acceleration is. So, you don't need engines big enough to do 3-5 gs, but you need ones big enough to do about 1.0 g acceleration at the bingo fuel point just before reaching zero velocity above the atmosphere, and throttlable down to whatever percent of G exists at the starting orbital altitude.