Depends on if you want to die or not. If you “come straight down”, as in, approach the atmosphere at 90 degrees, you will hit the thicker portion of the atmosphere very quickly, meaning you’ll be crushed like a bug hitting a windshield. Specifically, at 18,000 miles per hour, the speed of the space shuttle, you would need to slow down at 27g to avoid cratering. Humans can’t survive more than 8-10g for any real length of time.
The problem is you are dealing with space travel, and you need to realize the following points:
[ul]
[li]You don’t need to “acheive orbit around Earth”, because any time you are in space in the solar system, you are in an orbit. It may be a solar orbit, or an Earth orbit, or a Jupiter orbit, but it’s an orbit.[/li][li]You can transfer from one orbit to another by burning rocket fuel or otherwise applying thrust. At all times you are still in an orbit.[/li][li]You can transfer from orbit around one body to an orbit around another, simply by coming close enough to the second body.[/li][li]For example, if you are in solar orbit (which anything closer than Pluto is) if you come within, say, 100,000 miles of Earth you are now in an Earth orbit. It is likely that you have enough energy to exit Earth orbit and go back into a new, different, solar orbit.[/li][li]All orbits have a point of closest approach to the body they are orbiting. In an Earth orbit, this is called perigee. In a solar orbit, this is called perihelion.[/li][li]When you are at perigee (or perihelion…) you are going as fast as you ever will in the orbit you are in.[/li][li]When you are at perigee, it is not possible to be going slower than a circular orbit at that same altitude.[/li][/ul]
Given all these facts, it means that the slowest you can go when you hit the top of the atmosphere is the speed of a circular orbit of that altitude (say, 75 miles.) It also means that the space shuttle is already going that slow, since it’s in orbit not much higher than that for its entire mission.
So, any spacecraft on any orbit will be going faster than the space shuttle when it hits. The only way around this is to rapidly decrease your speed using rockets. The problems with that are, as have already been pointed out, that’s how we got to space in the first place - remember that big fuel tank and two big solid rocket boosters? We need them back again.
Note that a manned spacecraft has already done the “approach Earth without entering (a circular) orbit” thing, the Apollo lunar missions approached from the moon and were going much faster than the shuttle on reentry. Slowing down was not an option.
As for the reentry parachute idea, any molecules you get hitting you at 18,000 miles per hour are going to heat you up ridiculously hot. There is no such thing as just a little bit of heat on reentry.