Satellites are launched to a variety of orbits. Low Earth Orbit (LEO) ranges from an altitude above sea level of approximately 100 miles through about 1200 miles. The International Space Station is in a LEO orbit. Higher satellite orbits are also useful for a variety of satellite applications. Medium Earth Orbits (MEO) range from approximately 1200 miles to approximately 22,000 miles above sea level. Geosynchronous Orbit (GEO) is approximately 22,200 miles above sea level.
The cost of launching a satellite varies depending on the satellite mass, the orbital altitude, and the orbital inclination of the final satellite orbit. Launch costs range from approximately $5000 per kg to LEO to $30,000 per kg to GEO. The cost of the satellite launch is exponentially related to the mission Delta V. Destinations beyond geosynchronous orbits (such as lunar transfer orbit and Mars transfer orbit) require even larger Delta Vs and correspondingly, require significantly higher launch costs per kg.
Using a Cannae-Drive-based system, payloads that are in a LEO orbit can be accelerated along the satellites orbital path. The increases to the velocity of the satellite raise the satellite orbit. In addition to the increased altitude of the orbit, orbital inclination changes can also be induced with the Cannae Drive system. The concept video below depicts a Cannae-Drive-thrusted vehicle which tows payload satellites from LEO to higher orbits.
The concept outlined in this section of the website is a space freighter that is based on the reactionless thrust of the Cannae Drive. This freighter is a satellite that is launched to LEO on a standard 5 meter fairing launch vehicle. Once in orbit, the freighter is used to raise the orbits of other satellites that are already in a LEO orbit. The value of the freighter is that significant reductions in launch costs are achieved. Satellites that are destined for orbits higher than LEO require only the launch costs associated with the LEO launch. For larger GEO satellites, the launch cost savings can amount to greater than $200 million per satellite. The launch configuration of the space freighter is depicted in Figure 1 below.
The freighter is designed to operate in Earth orbit between LEO and GEO altitudes (100 miles to 22,200 miles). The design described here is a basic overview of system configuration and operation based on state-of-the-art performance levels for the subsystems required to operate the freighter in space. Figure 2 below depicts an underside view of the freighter. Figure 3 depicts a side view of the freighter.
Space Freighter Specs
- MASS: 10,000 KGS
- SOLAR POWER REQUIRED: 4000 WATTS
- FREIGHTER DIAMETER: 4.8 METERS
- LENGTH: 10 METERS
- PHASE LOCKED RF POWER: 40 WATTS
- CAVITY COOLING POWER REQUIRED: 40 WATTS AT 70 K
- BRAYTON COOLER POWER: 1600 WATTS
- COOLING FLUID: NEON GAS
- SUPERCONDUCTOR: YBCO
- CAVITY FREQUENCY (THRUSTER): 50 MHZ
- CAVITY FREQUENCY (STEERING): 200 MHZ
- CAVITY FREQUENCY (ROLL): 1 GHZ
A rendition of the Cannae Drive cavity configuration is depicted in Figure 4 below.
The freighter operates by rendezvous with a satellite that is to be moved from LEO to a new orbit. The freighter attaches to the payload satellite (referred to as payload) using a remotely operated robotic arm which attaches to a hitch located on the payload. Once the freighter is mechanically linked to the payload, the main thruster Cannae Drives are powered with approximately 40 watts of phase-locked RF power. The H-field located on the top plates of the 3 thruster Cannae Drives is approximately 3000 A/m. With a design differential between the top and bottom plates of approximately 20%, the RF power induces a linear unbalanced force of approximately 26 Newtons. The freighter and payload accelerate in the direction of the payload orbit and the payload increases orbital altitude.
The steering Cannae Drive cavities are operated to steer the system of the freighter and payload. Modulation of the power into the steering cavities is used for orbital inclination changes and orbital corrections.
The 3 small cavities are used to adjust and correct the roll rate of the payload. In addition to the Cannae Drives located on the freighter, additional Cannae Drive cavities are located on the payload satellite. These additional cavities are used for station keeping once the payload satellite is placed into its desired orbit. In addition to the station-keeping function of the Cannae Drives located on the payload satellite, these cavities are also used during freighter docking.
A GEO payload satellite of 10,000 kg mass is built and ready to launch. Currently, this satellite is launched on a rocket into a geosynchronous transfer orbit (GTO). The satellite then uses an apogee motor to circularize the orbit and correct the orbital inclination. The 10,000 kg GEO satellite must be launched on a heavy lift launcher such as a Delta IV heavy, an Ariane 5 ECA, or another heavy-lift launch system.
Using the Cannae Drive freighter system, this 10,000 kg mass can be launched to LEO with a medium lift launcher. A variety of launch vehicles are capable of lifting this mass to LEO. The cost differential between a launch directly to GTO and LEO are significant. A Delta IV heavy launch costs are approximately $300 million. A Falcon 9 medium lift launch costs approximately $56 million and is capable of placing 10,000 kgs in LEO orbit. The Cannae Drive freighter is used to take the 10,000 kg payload from LEO to GEO orbit (including any inclination and roll rate corrections that are required). Use of the Cannae Drive freighter saves approximately $240 million in launch costs for the 10,000 kg GEO satellite.
Note: a portion of the 10,000 kg satellite weight is propellant used for orbit circularization and station keeping. The overall satellite weight will be reduced by the elimination of propellant weight through use of the freighter and through use of station keeping Cannae Drives on the payload satellite.
The Delta V required to change the payload inclination and orbit from LEO to GEO is assumed to be 2500 m/s. The combined mass of the freighter and the payload is 20,000 kgs. The total impulse required to raise this mass to GEO is 50 million kg-m/s. The freighter requires approximately 22 days of continuous operation at 40 Watts RF to impart this impulse.
During periods when the freighter is in the Earth’s shadow, RF power is sent into the thruster cavities by use of battery power. The neon gas in the cavity cooling chamber is allowed to increase in temperature during the pass through the Earth’s shadow. During exposure to sunlight, power is available to cool the neon gas. Using this method, continuous thrusting is achieved. The neon gas temperature fluctuates between 70 and 75 K. Neon gas is cooled to 70 K during periods of sunlight, and allowed to heat up to 75 K during periods of shadow. Continuous cooling of the cavities is accomplished without the use of battery power.
Once the payload is delivered to GEO, the freighter reverses direction and continues to accelerate. This drops the orbital altitude of the freighter. Once the freighter returns to LEO, another payload satellite is picked up for transfer to GEO. Using this method, multiple satellites per year can be placed into GEO orbit by a single Cannae Drive freighter. Annual GEO satellite launch forecasts are for 20 satellites per year. Two Cannae Drive freighters can handle the entire worldwide GEO launch demand saving billions in annual launch costs.
Note: The Cannae Drive freighter is not dependent on propellant for thrust. With no moving parts in the thruster, operational life for a Cannae Drive freighter is expected to be at least 15 years, and can be designed for longer operational life.
SPACE PROBE LAUNCH
Because of the high Delta V requirements for launch of vehicles beyond GEO orbit, the size of deep space and planetary probes is significantly restricted by current launch limitations. The mass fraction of propellant required by the Delta V of the probe in addition to the payload limitation of the launcher limits the mass of the probe to a few tons. With the Cannae Drive freighter, deep space probes can be launched to LEO and then lifted to beyond GEO by the freighter. Once in a high earth orbit, the probe can use on board Cannae Drives to impart any additional Delta V required by the mission.
With this system of LEO launch and freighter-assisted orbital ascent, the mass of deep space and planetary probes is restricted only by LEO launch limits. Currently, launch systems exist which can launch in excess of 22,000 kgs to LEO. Launcher’s are being developed which can launch in excess of 50,000 kgs to LEO. For comparison, the Mars Curiosity rover and landing system has a total mass of 3500 kgs. The rover was launched on an Atlas V 541 at an estimated launch cost of greater than $200 million. Using the Cannae-Drive-freighter orbital boost, twice this mass can be sent to Mars for approximately 1/4 the launch cost.
The Cannae Drive freighter system allows significant launch cost reductions for satellite and space probe operators. With an operational Cannae Drive freighter system, direct launch to orbits beyond LEO is obsolete because of high costs. With the freighter lift system, space vehicle operators require only LEO launch services. There are a number of countries and suppliers competing for LEO launch services, ensuring long-term price competitiveness. In addition, the significant development costs associated with new heavy lift launchers capable of directly launching the mass needed for manned lunar and deep space flight is unnecessary.