Atlas II's booster assembly, called MA-5A massed about 4 tons. It was jettisoned at 172 seconds into flight. https://en.wikipedia.org/wiki/MA-5A

The launcher's payload to LEO is about 6.8 tons; if the booster engines were shut down at the same point but retained rather than dropped, it could only lift 2.8 tons payload. Keeping the engines burning a little longer could improve the payload slightly, but the longitudinal acceleration would get quite severe.

The original Atlas launcher could lift only around a ton (depending on version) to LEO, by dropping its 3-ton booster section; without the half-staging it would not reach LEO at all.

Atlas II's booster assembly, the MA-5A, massed about 4 tons. It was jettisoned at 172 seconds into flight.

The launcher's payload to LEO is about 6.8 tons; if the booster engines were shut down at the same point but retained rather than dropped, it could only lift 2.8 tons payload. Keeping the engines burning a little longer could improve the payload slightly, but the longitudinal acceleration would get quite severe.

The original Atlas launcher could lift only around a ton (depending on version) to LEO, by dropping its 3-ton booster section; without the half-staging it would not reach LEO at all.

Atlas II’s booster assembly, called MA-5A massed about 4 tons. It was jettisoned at 172 seconds into flight. https://en.m.wikipedia.org/wiki/MA-5A

The launcher’s payload to LEO is about 6.8 tons; if the booster engines were shut down at the same point but retained rather than dropped, it could only lift 2.8 tons payload. Keeping the engines burning a little longer could improve the payload slightly, but the longitudinal acceleration would get quite severe.

The original Atlas launcher could lift only around a ton (depending on version) to LEO, by dropping its 3-ton booster section; without the half-staging it would not reach LEO at all.

Atlas II's booster assembly, called MA-5A massed about 4 tons. It was jettisoned at 172 seconds into flight. https://en.wikipedia.org/wiki/MA-5A

The launcher's payload to LEO is about 6.8 tons; if the booster engines were shut down at the same point but retained rather than dropped, it could only lift 2.8 tons payload. Keeping the engines burning a little longer could improve the payload slightly, but the longitudinal acceleration would get quite severe.

The original Atlas launcher could lift only around a ton (depending on version) to LEO, by dropping its 3-ton booster section; without the half-staging it would not reach LEO at all.