A Spacecraft reaches the orbital level when it goes toLow-Earth Orbit (LEO) between 180 –3000 km –High Earth Orbit (HEO) –Geocentric 35,786 km
At those orbits, the Tourist Industry can offer spending long periods of time in microgravity at ISS or on private space stations. One example is Space Adventures where 7 private citizens can goes at ISS for 8 missions at a cost of $20M to $40M per trip. At this level, we can do some research and conduct experiments in microgravity and life sciences.
For Commercial purpose, we can launch small sats from ISS and make Satellites Servicing, where we put them in proper orbits, refuel, fix and upgrade systems.
Private Space Station
International Space Station, ISS
A Spacecraft reaches the deep space level when it goes at Lagrange points, Moon, Asteroids, Mars and beyond. Well, here we have some kinds of Tourist and Explorers who can make exotic experiences in the same way of The Inspiration of Mars Foundation. Example of that is the proposed seat to the Moon by Golden Spike Company for $750M.
In its ultimate destinations in space, happy humans can be productive and in developing new materials and processes to create new markets and improve life, we develop in-space economy. That mean, proceeding mining and In situ Resource Utilization for Propellants, metal and building new materials.
These development provide a new space-based economy for as well as 3D printing and space manufacturing... and more. It will be also possible to establish settlement by moving human civilization to Moon and Mars.
Moon's Workers for Settlement
PROPULSION WITHOUT FUEL!
We can do it in using techniques of Aeroassit, which includes Aerocapture, Aerobraking, entry and Aerogravity Assist maneuvers.
So, when a spacecraft do many passes through the atmosphere of a planet with only small changes during each pass, that means passing from a larger eccentricity to a smaller, it makes Aerobraking maneuver. During a single pass, the initial and the final states of the spacecraft are bound orbits at the primary. Today example of that it’s the Grand Finale of Cassini on Saturn planet in September 2017. Learn more about that. See below.
Unless many variants exist of this maneuver, if a spacecraft enter into a planet’s atmosphere from a bound or unbound orbit and makes a fully decelerated state, it makes an atmospheric entry.
The spacecraft can entry directly in decreasing monotonically its altitude throughout the entry maneuver. Because it is direct, it can be landing on a solid or liquid surface (like Titan’s lakes), or complete a mission while still in the atmosphere, as giant planet entry probes as well as a Venus balloon.
A second variant used is the “skip entry”, where the spacecraft enters the atmosphere and decelerates partially, exit and then re-enter for a final deceleration. This latter method is often applied to very high-energy entries, allowing more gradual deceleration and increased landing location accuracy.
So, if the location is not important, the direct entry maneuver can be applicate without flight path control. But, if it is important and has relatively small tolerances, a guided entry might be more appropriate. That is why, Aerobraking is more challenging than Aerocapture, but necessary, for critical payload like the Mars Science Lander or “Curiosity.” In that latter case, operational team use a flight path control during the hypersonic phase of the entry.
When a spacecraft, in addition to the gravitational forces, uses the aerodynamic forces generated during a flight through a body’s atmosphere, it maneuvers in Aerogravity assist. That method is useful for a body with a weak gravitational field that cannot provide the hyperbolic bending angle needed for a near-optimal gravity assist maneuver, but with a relative atmosphere, it can generate aerodynamic forces sufficient to achieve it.
Unlike Aerocapture, the approach and departure orbits of an Aerogravity assist maneuver are unbound with respect to the body whose atmosphere is used, so the vehicle’s ultimate destination is usually elsewhere.
Most examples in the literature describe Aerogravity assist as a means to achieve extremely high heliocentric velocities (on the order of 50–100 km/s) or high-energy trajectories to the outer solar system, applications that would require significant advances in thermal protection system technology.
But an Aerogravity assist maneuver can also decrease a vehicle’s orbital energy relative to a third body. For example, a spacecraft could use a relatively gentle Aerogravity assist in Titan’s atmosphere to capture into Saturn orbit, as seen in the upper graphic.
POTENTIAL BENEFITS OF AEROCAPTURE
For a particular launch vehicle, there are three categories of potential benefits from using Aerocapture instead of propulsive orbit insertion.
First, when a spacecraft use Aerocapture, it can deliver more payload mass to orbit, mean the destination. Simply, because the mass of hardware needed for the Aerocapture maneuver is less than the propulsion hardware and propellant needed to perform the insertion. This difference is available for increased science payload and spacecraft subsystems to support it.
Second, it decreases the trip time from launch at Earth to the destination. Why? Because we have a higher V∞ of approach from shortening a mission’s trip time, the ΔV for orbit insertion increases.
Finally, we can also say that, given a fixed science payload and trajectory, Aerocapture allow launching on a less costly launch vehicle. That cost price depends strongly upon the destination, especially the destination’s heliocentric distance. Studies by NASA’s Aerocapture Systems Analysis Team (ASAT)indicate that the increase in delivered payload can range from about 15% at Mars, to more than 200% at Titan and Uranus, to more than 800% at Neptune.