Rockets into Outer Space, from Small to Large

[lpetrich]

•  List of orbital launch systems
•  Comparison of orbital launch systems
•  Comparison of orbital launcher families
•  Comparison of solid-fuelled orbital launch systems
•  Comparison of orbital rocket engines

A surprisingly big list, with several nations having entries in it, and with the biggest spacefarers having several entries in it.

A good benchmark for orbit-capable rockets is how much they can lift to low Earth orbit (LEO). That is because one has to go there before going any further, even if one is only passing through.

All of the all-solid systems go up to only 2 metric tons (mt) into LEO. Anything more is partially or completely liquid-fueled.

Broken down by size:

•  Small-lift launch vehicle to LEO: <= 2 mt
•  Medium-lift launch vehicle to LEO: 2 mt to 20 mt
•  Heavy-lift launch vehicle to LEO: 20 to 50 mt
•  Super heavy-lift launch vehicle to LEO: >= 50 mt

ROSCOSMOS (Russian space agency) uses different classifications from the one used by NASA and Wikipedia:
Small - 5 mt - Medium - 20 mt - Heavy - 100 mt - Super heavy

 Sounding rocket - goes up to outer space, but does not go fast enough to orbit, and thus quickly returns

How far do the spacecraft go?

• LEO -  Low Earth Orbit - up to 2,000 km altitude
• MEO -  Medium Earth orbit - 2,000 to GSO altitude
• GSO -  Geosynchronous orbit - 35,786 km altitude - tracks the Earth's rotation
• GEO -  Geostationary orbit - 35,786 km altitude - above one spot on the Earth's equator - payload: 1/5 * LEO payload
• HEO -  High Earth orbit - GSO to 1.5 million km (L1, L2) altitude
• SSO -  Sun-synchronous orbit - it tracks the Sun with its precession - typically LEO or MEO - payload: 1/1.5 * LEO payload
• GTO -  Geosynchronous Transfer Orbit and  Geostationary transfer orbit - for getting into GSO or GEO - payload: 1/2.5 * LEO payload
• TLI -  Trans-lunar injection - for reaching the Moon: payload: 1/3 * LEO payload
• TMI -  Trans-Mars injection - payload: 1/3 * LEO payload
• HCO -  Heliocentric orbit - payload: 1/3 * LEO payload

An odd result is that it's harder to go into a geosynchronous orbit than to escape from the Earth's gravity. To see why that is, let us work out velocity changes or delta-V's.

Typical LEO altitudes are around 400 kilometers, and that means an orbital velocity of 7.67 km/s and an orbital period of about 1.5 hours. One typically needs a rocket delta-V of 9 or 10 km/s to overcome the Earth's gravity and atmospheric drag, about 1 or 2 km/s extra.

To get into a GTO, one needs a delta-V of 2.4 km/s, and to get into a TLI or TMI, one needs 3.2 km/s. Once one gets to one final altitude, one needs an additional delta-V of 1.5 km/s to get into a GSO, because without it, one will return to one's starting altitude.

SSO takes some additional engine burn because that sort of orbit is usually a near-polar orbit, and one won't have the assistance of the Earth's rotation, about 460 m/s at the Equator. That orbit makes use of the Earth's equatorial bulge to make it precess enough to track the Sun's position relative to the Earth. One can thus have dawn/disk orbits and noon/midnight orbits.

 

[lpetrich]

Some special kinds of spacecraft:

•  Comparison of crewed space vehicles
•  Comparison of space station cargo vehicles

Space-station cargo spacecraft have parts of them pressurized, so that the space-station crew can bring in the deliveries and put trash aboard it.

Looking at the crewed one, there is an approximately linear relation between the crew size and the spacecraft mass, roughly 2.5 mt per crewmember.