Abstract: Retrofittable satellite systems for an in-orbit host satellite comprising an enhancement module for adding a capability to the in-orbit host satellite, modifying the function of the in-orbit host satellite, and/or extending the function of the in-orbit host satellite. The in-orbit, retrofittable satellite system comprises a transfer vehicle for transferring the enhancement module from a first to a second location and a service vehicle for receiving the enhancement module from the transfer vehicle and installing the enhancement module on the in-orbit host satellite.

Abstract: A satellite system may have a constellation of communications satellites in orbits such as highly inclined eccentric geosynchronous orbits and low earth orbits. To place satellites in inclined eccentric geosynchronous orbits, a series of launch vehicles may be launched. Each launch vehicle may be used to place a set of satellites, such as a set of three satellites, into a common orbital plane with distinct longitude of ascending node values. To place satellites in low earth orbits, a series of launch vehicles may be launched, each of which releases satellites in sequence from a stack of satellites into a common orbital plane. After desired separations have been produced between the released satellites, circularization procedures may be performed using the propulsion systems of the satellites to place the satellites into final orbit.

Abstract: The present invention relates to a resident space object orbit determination system comprising a high efficiency module for determining a resident space object's orbit and a highly efficient method for determining same. Applicants developed a method and system to determine the orbits of residence space objects including resident space objects that do not reflect energy that is directed at them and/or may be coated to minimize the ability to accurately see such resident space objects. Thus, a method, a module and a system for making such determinations that can easily and inexpensively be added to an early warning reentry system is provided.

Abstract: An aircraft based satellite communication (SATCOM) terminal includes a broadband aperture configured to communicate through non-geostationary orbit (NGSO) satellites for broadband communications, a management aperture configured to receive NGSO satellite management information from a geostationary orbit (GSO) satellite, and at least one processor that performs operations. The operations receive the NGSO satellite management information from the GSO satellite, where the NGSO satellite management information indicates positions and associated time of a set of the NGSO satellites. The operations acquire a second communication link with a second NGSO satellite among the set using the NGSO satellite management information during handoff switching from using a first communication link that was previously acquired with a first NGSO satellite to using the second communication link being acquired with the second NGSO satellite.

Abstract: A reconnaissance rover configured for multiple agile and autonomous landings over a small body or moon. The reconnaissance rover comprises a detection unit, a processing unit, a control unit and a drive unit. The detection unit is configured to detect at least an environment in front of the reconnaissance rover, in the direction of a trajectory of the reconnaissance rover over a surface of the small body or moon. The detection unit is further configured to provide environmental data based on the detected environment. The processing unit is configured to update the trajectory based upon the provided environmental data. The control unit interacts with the drive unit to move the reconnaissance rover according to the updated trajectory.

Abstract: Systems and methods are described herein for adaptive pointing operations of a mobile antenna system that can be used to provide communication with a target satellite over a large geographical area, while also satisfying interference requirements with one or more other satellites. In particular, the adaptive pointing operations described herein control pointing of a beam of the antenna system towards the target satellite in a manner that takes into consideration the interference requirements of the other satellites. In some embodiments, the mobile antenna system can provide non-interfering communication with the target satellite, over the entire or substantially the entire coverage area (or footprint) of the target satellite. In doing so, services such as Internet, telephone and/or television services provided by the target satellite can be delivered to users throughout most or all of the satellite's coverage area, while also satisfying interference requirements with other satellites.

Abstract: A method for controlling a first device that includes a photovoltaic array such as a satellite in Earth orbit includes receiving a laser beam that is scanned over a plurality of photovoltaic cells in the photovoltaic array. A trajectory of the laser beam along the photovoltaic array is identified based on receipt of the laser beam by the plurality of photovoltaic cells. The trajectory is compared to a plurality of pre-defined gesture strokes to identify a first gesture stroke most closely matching the trajectory. A pre-defined action associated with the first gesture stroke is performed.

Abstract: A smart satellite system is capable of decision making and prioritization on the fly to optimize the use of downlink bandwidth to deliver prioritized data based upon opportunity and the resources of available payloads. By providing a satellite system with substantial processing power and a level of autonomy, the satellite is able to make decisions about capturing imagery data, including image data processing, object detection, image segmentation, and re-orientation of the satellite based upon the opportunity, from the satellite's perspective, for capturing image data of areas or objects of interest. Through the use of machine learning and in-orbit image analysis, the satellite may transmit only a subset of the captured images, portions of the captured images, or the result of image analysis, thereby efficiently using the downlink communication channel.

Abstract: Systems, methods, and apparatus for a constellation design for a Martian synchronous orbit are disclosed. In one or more embodiments, a system for communications comprises at least one antenna on Mars in communication with at least one Martian satellite. In one or more embodiments, at least one Martian satellite is located in an areosynchronous orbit (ASO) around Mars. The system further comprises at least one Martian satellite in communication with at least one antenna on Earth. In at least one embodiment, at least one Martian satellite is part of a Martian areosynchronous satellite constellation, which comprises a total of at least four Martian satellites. In some embodiments, the areosynchronous orbit (ASO) is an areostationary orbit.

Abstract: A satellite system may have a constellation of communications satellites that provides services to users with electronic devices such as portable electronic devices and home and office equipment. A network operations center may use gateways to communicate with the satellite constellation. The satellite constellation may include sets of satellites with different orbits such as circular orbits with different inclinations, sets of satellites with elliptic orbits, sets of satellites with circular orbits of different altitudes including low earth orbits, medium earth orbits, and/or geosynchronous orbits, and/or sets of satellites with other orbits. The satellite orbits of the satellites in the satellite constellation may be selected to provide coverage to desired user population concentrations at different locations on the earth without using an excessive number of satellites.

Abstract: An interference effect mitigating method may be a method of mitigating interference effects of a mobile earth station to a terrestrial radio station. The interference effect mitigating method may include collecting position information including a position, of a communication device of a first wireless communication network, which changes over time, determining an antenna discrimination angle based on the collected position information, and determining a transmission power and a transmission scheme of the communication device of the first wireless communication network based on the determined antenna discrimination angle, to mitigate interference effects of the communication device of the first wireless communication network to a communication device of a second wireless communication network.

Abstract: A station placed on a high-altitude stationary platform includes two main emitter/receiver sets, each configured to establish a main communication link with a remote terminal station or with another station placed on a high-altitude stationary platform and two backup emitter/receiver sets, each configured to establish a backup communication link with a repeater placed on a relay station on the ground or at sea or with a remote terminal station, the station furthermore comprising a control facility configured to selectively activate a main communication link or a backup communication link as a function of an indicator of the operating state of the main communication link.

Abstract: A method for designing Non-Geosynchronous Orbit (NGSO) satellite constellations and NGSO satellite constellations thereof are presented. An NGSO satellite constellation may be designed to allow an earth station to perform handover between two satellites of the NGSO satellite constellation while the two satellites appear to be at about a same location in the sky relative to the earth station. In such constellation, an earth station may perform such handover between the two satellites in a Make-Before-Break fashion while the earth station may be configured to use a single, slow-tracking antenna, such as a mechanically tracking dish antenna.

Abstract: A satellite system may have a constellation of communications satellites that provides services to users with electronic devices such as portable electronic devices and home/office equipment. A network operations center may use gateways to communicate with the satellite constellation. The satellite constellation may include sets of satellites with different orbits such as circular orbits with different inclinations, sets of satellites with elliptic orbits, sets of satellites with circular orbits of different altitudes including low earth orbits, medium earth orbits, and/or geosynchronous orbits, sets of satellites with sun synchronous orbits, and/or sets of satellites with other orbits. The orbits of the satellites in the constellation may be selected to provide coverage to desired user population concentrations at different locations on the Earth, while reducing the amount of capacity that goes unused (e.g., is idle) at one or more times of day.

Abstract: A satellite system may have a constellation of communications satellites in orbits such as highly inclined eccentric geosynchronous orbits and low earth orbits. To place satellites in inclined eccentric geosynchronous orbits, a series of launch vehicles may be launched. Each launch vehicle may be used to place a set of satellites, such as a set of three satellites, into a common orbital plane with distinct longitude of ascending node values. To place satellites in low earth orbits, a series of launch vehicles may be launched, each of which releases satellites in sequence from a stack of satellites into a common orbital plane. After desired separations have been produced between the released satellites, circularization procedures may be performed using the propulsion systems of the satellites to place the satellites into final orbit.

Abstract: An illustrative embodiment disclosed herein is a satellite including a transceiver, a first antenna, a second antenna, and a switch to enable only the first antenna by electrically coupling the first antenna to the transceiver responsive to a satellite constellation having less than a threshold number of satellites and enable only the second antenna by electrically coupling the second antenna to the transceiver responsive to the satellite constellation having greater than the threshold number of satellites.

Abstract: A satellite system may have a constellation of communications satellites that provides services to users with electronic devices such as portable electronic devices and home and office equipment. A network operations center may use gateways to communicate with the satellite constellation. The satellite constellation may include sets of satellites with different orbits such as circular orbits with different inclinations, sets of satellites with elliptic orbits, sets of satellites with circular orbits of different altitudes including low earth orbits, medium earth orbits, and/or geosynchronous orbits, and/or sets of satellites with other orbits. The satellite orbits of the satellites in the satellite constellation may be selected to provide coverage to desired user population concentrations at different locations on the earth without using an excessive number of satellites.

Abstract: Method for placing a spacecraft into a lunar orbit, either by standard (i.e., impulsive) or ballistic (i.e., non-impulsive) capture, from an Earth orbit that is significantly inclined relative to the lunar orbit plane, with no constraint on the local time of perigee for the starting orbit.

Abstract: A satellite communication system comprises one or more non-geostationary satellites. Each satellite is configured to provide a plurality of spot beams. The polarizations of the spot beams are laid out on each satellite so that terminals have a constant polarization as the field of regard traverses the terminal location.

Abstract: Satellites in the direct-to-user Earth observation (EO) satellite system support inter-satellite communication and form a multihop communication network. Each satellite has a radio transceiver with a phased array antenna for directly communicating with a user radio station that issues an EO request of a user. Physical servers are distributed over the satellites and networked to form an in-space computer network that is Internet-enabled. The multihop communication network enables the servers to be mutually communicable. Raw data generated from the EO sensors are processed by the servers to yield desired EO data that meets the user's requirement. Advantageously, the servers set up a user authentication server configured to verify the user identity for determining acceptance or denial of the EO request, and an application server for interacting with the user. Hence, the EO request is entirely handled in Space without involving a terrestrial non-user facility for user authentication and raw-data processing.

Abstract: A high throughput satellite (HTS) and a method of operating the HTS for relaying data between a low earth orbit (LEO) satellite and a target ground station, where the HTS provides spot beams for a spot beam coverage area. The method of operating the HTS includes: determining an estimated trajectory of an orbiting LEO satellite; assigning a plurality of assigned spot beams having a matching color re-use polarization; and transmitting assignments of the plurality of assigned spot beams to the high throughput satellite to cause the high throughput satellite to maintain the inter-satellite link via a first spot beam and one or more assigned subsequent spot beams having the matching color re-use polarization.

Abstract: A system for displaying measurements of objects in orbit can include a display interface that includes a longitude-time graph. The interface can include a longitude axis spanning from a lower-longitude limit to an upper-longitude limit, a time axis spanning from a lower-time limit to an upper-time limit, and a plurality of pixels corresponding to longitude-time points within the longitude-time graph. Each of the plurality of longitude-time points may correspond to a data set that includes the historical data and the contemporary data. The data set includes a time identifier between the lower-time limit and the upper-time limit and a longitude identifier between the lower-longitude limit and the upper-longitude limit.

Abstract: The disclosed system comprises one or more small satellites (e.g., CubeSats), one or more ground transmitters, and one or more downlink receivers to facilitate ground-to-space short-burst data communications. The CubeSats are miniaturized or small-form satellites that orbit the Earth transmitting data to and from the ground transmitters and the downlink receivers in low Earth orbit. To efficiently use its surface area, in various embodiments, the CubeSats are designed with deployable and folding wings such that the zenith-pointing side of the wings comprises solar panels and the nadir-pointing side of the wings comprises an antenna. In various embodiments, to increase the data transmission capacity of the CubeSats, the CubeSats comprise a deployable phased array antenna and a software defined radio.

Abstract: A stationkeeping strategy for a satellite disposed in a TAP orbit includes controlling parameters of the orbit such that, for a constellation of two satellites disposed in the orbit, the constellation provides substantially continuous coverage of a polar region. The stationkeeping strategy includes one or more of: establishing an initial Right Ascension of Ascending Node (RAAN) of the operational orbit such that naturally caused orbital drift results in a mid-life RAAN of approximately 0 degrees (360 degrees); and controlling Argument of Perigee (ARGP), only indirectly, by performing orbit maintenance maneuvers only to directly control one or more of the operational orbit apogee altitude, the operational orbit perigee altitude, and inclination within a respective required range.

Abstract: A satellite system may have a constellation of communications satellites that provides services to users with electronic devices such as portable electronic devices and home and office equipment. A network operations center may use gateways to communicate with the satellite constellation. The satellite constellation may include sets of satellites with different orbits such as circular orbits with different inclinations, sets of satellites with elliptic orbits, sets of satellites with circular orbits of different altitudes including low earth orbits, medium earth orbits, and/or geosynchronous orbits, and/or sets of satellites with other orbits. The satellite orbits of the satellites in the satellite constellation may be selected to provide coverage to desired user population concentrations at different locations on the earth without using an excessive number of satellites.

Abstract: A constellation of Earth-orbiting spacecraft includes a first spacecraft disposed in a first orbit, a second spacecraft disposed in a second orbit, and a third spacecraft disposed in a third orbit. Each of the first orbit, the second orbit and the third orbit is substantially circular with a radius of approximately 42,164 km, and has a specified inclination with respect to the equator within a range of 5° to 20°. The first orbit has a first right ascension of ascending node RAAN1, the second orbit has a second RAAN (RAAN2) approximately equal to RAAN1+120°, and the third orbit has a third RAAN (RAAN3) approximately equal to RAAN1+240°. A fourth spacecraft is disposed in a fourth orbit that has a period of approximately one sidereal day, an inclination of less than 2°, a perigee altitude of at least 8000 km, and an eccentricity between approximately 0.4 and 0.66.

Abstract: A laser communication system its integrated microradian-accuracy Acquisition and Tracking Sensor (ATS) to perform a celestial navigation fix to determine the attitude of the laser communications payload, including the integrated ATS and the co-boresighted laser beam, prior to establishing a laser communication link with a second vehicle such as a high-altitude aircraft or satellite. The laser communication system may use a legacy platform INS to initially point its narrow FOV ATS at one or more stars to obtain the vehicle's attitude therefrom. Then the precision payload attitude determined with the ATS star tracker fix is used to point the co-boresighted laser beam to establish a laser communications link with the second vehicle.

Abstract: A method for reducing expected switchovers in antennas tracking at least one satellite. The method predicts an operation of a predetermined number of subsets of antennas during a simulated time interval. The subsets are derived from at least three antennas. Each of the at least three antennas has a field of view and is operative to selectively receive signals from and selectively transmit signals to a satellite in the respective field of view. The method determines, based on the predicted operation, an expected number of switchovers for each of the subsets during the simulated time interval. The method selects a selected subset from the subsets for communicating with the satellite. The selection of the selected subset is based on the expected number of switchovers.

Abstract: Methods and apparatus to methods and apparatus for performing propulsion operations using electric propulsion system are disclosed. An example method includes deploying a space vehicle including an electric propulsion system; and using the electric propulsion system for attitude control and orbit control, no other propulsion system provided to enable the attitude control and the orbit control.

Abstract: A method and apparatus for operating one or more satellites in a non-geosynchronous orbit (NGSO) satellite constellation are disclosed. In some aspects, a coverage area on Earth for a first beam transmitted from a first satellite in the NGSO satellite constellation may be determined, a cone may be projected onto a first region of the beam coverage area, a second region of the beam coverage area may be defined as including portions of the beam coverage area lying outside the first region, and a minimum arc angle for each of a plurality of points within the first region but not the second region of the beam coverage area may be determined.

Abstract: Techniques for placing a satellite into a highly inclined elliptical operational orbit (HIEO) having an argument of perigee of 90° or 270° include executing an orbit transfer strategy that transfers the satellite from a launch vehicle deployment orbit to the operational orbit. The launch vehicle deployment orbit is selected to have an argument of perigee of approximately 90° greater than the argument of perigee of the operational orbit, and to be substantially lower than the operational orbit. The orbit transfer strategy includes (i) an apsidal rotation of approximately 90°, at least a substantial part of the apsidal rotation being attained without expenditure of any satellite propellant; and (ii) an electric orbit raising maneuver to attain an apogee altitude and a perigee altitude required by the HIEO.

Abstract: A plurality of orbiting solar generators stay in constant touch. They can be congregated rapidly in space at any desired secret location. Once congregated selected members of the group focus their energy to a death star. This death star could be a newly launched ICBM with a giant capacitor and a means to connect this capacitor to the selected members of the group of orbiting solar generators. A laser generator uses this giant capacitor energy to project a non-nuclear laser death ray to a target. The target could be a city, a ship or a satellite. In the event of an asteroid approaching earth, this system could destroy an asteroid. In peacetime, the orbiting solar generators may supply electric power to an earth based power grid or other space vehicles.

Abstract: A multi-functional optical subsystem for a spacecraft includes a laser diode module having output optics; an imaging and communication detector assembly; and a forward metering structure. The multi-functional optical subsystem is adapted for laser-based optical communication and attitude determination. According to embodiments, the subsystem fits within a small satellite having less than about 20 kg mass and less than about 10,000 cm3 total volume.

Abstract: Techniques for placing a satellite into a highly inclined elliptical operational orbit having an argument of perigee of 90° or 270° include executing an orbit transfer strategy that transfers the satellite from a launch vehicle deployment orbit to the operational orbit. The launch vehicle deployment orbit is selected to have an argument of perigee of approximately 90° greater than the argument of perigee of the operational orbit, an apogee altitude of approximately 14000 km and a perigee altitude of approximately 500 km. The orbit transfer strategy includes (i) an apsidal rotation of approximately 90°, at least a substantial part of the apsidal rotation being attained without expenditure of any satellite propellant; and (ii) an electric orbit raising maneuver to attain an apogee altitude and a perigee altitude required by the HIEO.

Abstract: A system comprises a constellation of satellites placed in non-geostationary orbit, user terminals located in a coverage area, and N anchor stations able to ensure bidirectional communications with the user terminals by way of at least one satellite. The system furthermore comprises a network of routers interconnected with one another and to the Worldwide Internet Network, each anchor station is connected to the Worldwide Internet Network by way of a router, and each anchor station comprises a management device for managing the handovers to ensure service continuity for the communications. This management device is able to control the handovers between the successive orbiting satellites progressing over the coverage area, the handovers between anchor stations, or the handovers between simultaneously successive satellites and anchor stations.

Abstract: Example methods and systems for assigning tasks to balloons within a balloon network are described. One example system includes a first sub-fleet of balloons assigned a first set of one or more tasks within a balloon network, a second sub-fleet of balloons assigned a second set of one or more tasks within the balloon network, and a control system configured to determine that a first balloon in the first sub-fleet of balloons initially has a predicted failure mode that corresponds to the first set of tasks, subsequently determine that the first balloon has a predicted failure mode that corresponds to the second set of tasks, and reassign the first balloon from the first sub-fleet of balloons to the second sub-fleet of balloons.

Abstract: A first inclination vector associated with a first satellite of the plurality of satellites is established. A second inclination vector associated with a second satellite of the plurality of satellites is established. The first satellite and the second satellite are controlled, such that the first satellite and the second satellite are synchronized with a node.

Abstract: A method of calibrating a spectrometer, while orbiting the Earth, includes the steps of (a) determining a period of time in which the Moon is within a field of view (FOV) of the spectrometer and (b) stopping the FOV of the spectrometer during this period of time. During this period of time, multiple “free views” of the Moon are available, in which lunar IR intensities may be received by the spectrometer that are comparable to intensity levels obtained from an internal calibration test (ICT) on a satellite. The method measures the IR radiance from the Moon during this period of time. After filtering the lunar IR radiances by an integral function, the spectrometer is calibrated using the “free views” as a benchmark.

Abstract: A system has a plurality of spacecraft in orbit around the earth for collecting energy from the Sun in space, using stimulated emission to configure that energy as well defined states of the optical field and delivering that energy efficiently throughout the region of space surrounding Earth.

Abstract: A method of solar occultation, and in particular solar coronagraphy, employing a spacecraft 200 is disclosed. The spacecraft is controlled to achieve a position within a target zone relative to a celestial body, such as the Moon, such that the celestial body occults the Sun, allowing observations of the Sun or the space around the Sun, and in particular the Sun's corona, to be made from the spacecraft. The spacecraft has an orbit 40 around the Earth in a plane S, which like the Moon's orbit 20 in plane M, is inclined relative to the ecliptic plane E. Once inside the target zone, the spacecraft's orbit is controlled such that it remains in the target zone for longer than it would otherwise. This is achieved through the orbit within the target zone being at least partly non-Keplerian, when the orbit is under the influence of spacecraft translational thrust for example.

Abstract: A satellite inclination control method is provided. The method includes tracking optimal inclination vector control cycles for a satellite in near geosynchronous orbit, using control rates disposed to counter inclination growth of the satellite, where the control rates include continuously or quasi-continuously firings of a thruster, and where the control rates are disposed to provide convergence to the optimal inclination vector control cycles in the presence of variances in orbit determination, maneuver implementation and orbit propagation modeling errors.

Abstract: A space probe including a descent module with a mobile exploration vehicle, wherein the descent module is a landing module inside which the mobile exploration vehicle is fastened, the landing module being provided with landing legs which can be deployed under the lower level of the mobile exploration vehicle.

Abstract: A dozen or more orbiting solar generators stay in constant touch. They can be congregated rapidly in space at any desired secret location. Once congregated they all focus their energy to a death star. This death star is a newly launched ICBM with a microwave or laser collector. A laser generator uses this huge energy to project a non-nuclear death ray to a target. The target could be a city, a ship or a satellite. In the event of an asteroid approaching earth, this system could destroy an asteroid. In peacetime the orbiting solar generators supply electric power to an earth based power grid.

Abstract: A method and apparatus for generating avoidance data. Strips are generated for a path of a space object. The strips are positioned relative to the path of the space object. The strips have parameters that obscure an identification of the path of the space object to form the avoidance data.

Abstract: The disclosed method involves calculating, with at least one processor, a desired orbit for the spacecraft. The method further involves calculating a velocity change required to achieve an orbit eccentricity, a velocity change required to achieve a semi-major axis, and a velocity change required to achieve an orbit inclination; all of which correspond to the desired orbit for the spacecraft. Also, the method involves calculating the direction of the vector sum of the velocity change required to achieve the orbit eccentricity, the velocity change required to achieve the semi-major axis, and the velocity change required to achieve the orbit inclination. Further, the method involves activating at least one propulsion device of the spacecraft in the direction of the vector sum in order to change the current orbit of the spacecraft to the desired orbit for the spacecraft, thereby changing the orbit eccentricity, the semi-major axis, and the orbit inclination simultaneously.

Abstract: Provided are a space debris removing device and a method which enable easy installation of a deceleration device to space debris undergoing a tumbling motion. The space debris removing device includes: a propulsion device (3) for performing approach and attitude control on target debris (1); a capture device (4) having a harpoon (41) which can be ejected toward the target debris (1); an observation device (5) for calculating a capture position (E) and a capture attitude at which the harpoon (41) can be driven into a tank (11) (hollow portion) of the target debris (1) by observing a motion of the target debris (1); a deceleration device (6) directly or indirectly connected to the harpoon (41), for decelerating the target debris (1); and a body part (21) on which the propulsion device (3), the capture device (4), the observation device (5), and the deceleration device (6) are mounted.

Abstract: A method of determining the reliability of long-term predicted orbit data, includes: determining the reliability of long-term predicted orbit data, which is acquired by predicting a satellite orbit in a target period of at least one day, using predicted position data including predicted positions of a positioning satellite in time series and actual position data including actual positions of the positioning satellite corresponding to the predicted positions.

Abstract: A satellite constellation includes a plurality of satellites in respective polar orbits. The orbits are spaced evenly in longitude and the satellites of adjacent orbits are spaced evenly in latitude. On board each satellite is one or more sensors for monitoring activity within the satellite's field of view.

Abstract: A method, a member satellite, and a tangible machine-readable medium are disclosed. An inter-satellite link subsystem 472 may maintain a fixed communication link between the member satellite and a partner satellite of the medium earth orbit centric satellite constellation in a regular, wraparound symmetric, spatially dimensional network. A terrestrial linking subsystem 476 may create a terrestrial link to a ground terminal.

Abstract: A space access system may include a reusable booster limited to sub-orbital operation and having a fuselage. The reusable booster may include a tri-propellant propulsion system which may be configured to shift from a tri-propellant mode of operation to a bi-propellant mode of operation. The tri-propellant propulsion system may include at least one tri-propellant engine and at least one internal propellant tank mounted within the fuselage and being fluidly coupled to the tri-propellant engine. A payload may be mounted with the fuselage. The payload may have an upper stage.