SATPC0038479 Tab 04 4 SOW..pdf

Aerocapture to Reliably Reduce Inertial Velocity with Aerodynamics and Lift (ARRIVAL)

Statement of Work

ARRIVAL Flight System Conceptual Design

1. Introduction/Background/Need

The National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) is in the early stages of developing a mission design and project implementation plan that could potentially lead to demonstrating aerocapture capability at Earth. Aerocapture uses the aerodynamics of an entry vehicle passing through a planet's atmosphere to reduce the vehicle's energy and insert a spacecraft into orbit.

Leveraging the vehicle's aerodynamics to lower its velocity reduces the capability and mass of the entry vehicle's propulsion system, enabling more mass to be allocated to the spacecraft and its payload.

Aerocapture capability has the potential to enhance select Mars Exploration missions, low-cost Mars missions, missions returning spacecraft to Earth from the Moon, and science missions to the Solar System's ice giant planets where the propulsive burden of orbital insertion is particularly challenging.

The Aerocapture to Reliably Reduce Inertial Velocity with Aerodynamics and Lift (ARRIVAL) flight demonstration would make aerocapture capability available for a range of NASA and commercial mission applications. NASA's intent with ARRIVAL is to mature and demonstrate key elements of aerocapture technology, including vehicle aerodynamics, flight dynamics, guidance, navigation and control, and mission operations. NASA will acquire flight data during the demonstration to improve and validate tools necessary for the design and planning of future missions.

NASA has developed a candidate reference design for the ARRIVAL aerocapture flight demonstration.

The reference design, described in Section 3, utilizes a Geostationary Transfer Orbit (GTO) as the initial state from which the ARRIVAL Flight System (AFS) would execute the lift-controlled aerocapture maneuver through the Earth's atmosphere. The AFS is comprised of a small blunt-body aeroshell, approximately 1-meter in diameter, that houses a small satellite (SmallSat) which controls the AFS flight and acquires and downlinks flight data to support the mission's technology development objectives.

This statement of work (SOW) describes the requirements for the Contractor to develop a conceptual design of the AFS for the ARRIVAL aerocapture flight demonstration. The objectives of the conceptual design are to verify the feasibility of the ARRIVAL reference mission described in Section 3 and identify technical and programmatic risks to mission success. Aspects of mission feasibility that NASA intends to verify with this design study include, but are not limited to, the following.

• Accommodating the AFS mass and volume on an ESPA Grande adapter

• Developing a SmallSat with the capabilities to execute the reference mission within the available mass and volume constraints

• Reliably performing the multiple mechanical and electrical separation and deployment events necessary to conduct the reference mission

• Acquiring, storing, and downlinking the volume of flight data needed to accomplish the mission technology development objectives within the available reference mission timeline

• Implementing the ARRIVAL reference mission within the available schedule and budget

2. Scope of Work

The Contractor shall develop a conceptual design of the AFS for the ARRIVAL aerocapture flight demonstration. The objectives of the AFS conceptual design are to verify the feasibility of the ARRIVAL reference mission described in Section 3 and identify risks to mission success. The conceptual design scope of work includes, but is not limited to, the following elements.

a) The Contractor shall develop a conceptual design of an AFS SmallSat that supports the ARRIVAL reference mission described in Section 3 and the AFS characteristics described in Section 4. The SmallSat design shall include concepts for all major SmallSat subsystems including, but not limited to, electrical power, telecommunications, avionics, command and data handling (C&DH), attitude determination and control, and propulsion. A concept shall also be provided for the SmallSat Flight Data System, which shall acquire and store measurements from the SmallSat inertial measurement unit (IMU) and the NASA-furnished entry system instrumentation (ESI) and on-board cameras. The Contractor shall provide the following design products, at a minimum, to support the SmallSat conceptual design.

• A block diagram of major SmallSat subsystems and interfaces

• Propulsion system delta-V requirements, thruster sizing and orientation, and provisions for propellant storage

• Attitude determination and control for orbit determination and control of SmallSat while in-orbit

• Electrical power system sizing data including battery and solar panel capacities

• Telecommunications architecture, data downlink strategy, and antenna placement

• A concept to integrate NASA-furnished guidance software with the SmallSat flight software

• Selection of the SmallSat IMU and Flight Data System components to acquire, store, and deliver data from the IMU and NASA-furnished ESI and on-board cameras

• Mechanical and electrical interfaces enabling the SmallSat to be deployed from the aeroshell following the aerocapture maneuver as described in Section 3

• A dimensioned SmallSat outline drawing

• A Master Equipment List (MEL) summarizing the SmallSat subsystem mass estimates with recommended mass growth allowances in accordance with AIAA-S120, Mass Properties Control for Space Systems

b) The Contractor shall develop a concept of the integrated AFS assembly that supports the ARRIVAL reference mission described in Section 3 and the AFS characteristics described in Section 4. The AFS assembly shall include the SmallSat, aeroshell forebody and backshell structures, mechanisms, reaction control system, and NASA-specified thermal protection systems and ESI. The Contractor shall provide the following design products, at a minimum, to support the concept for the integrated AFS assembly.

• A dimensioned AFS outline drawing. NASA's intention is for the AFS to conform to the geometry described in Section 4. The Contractor may alter the geometry of the AFS backshell, with approval from NASA, if necessary to accommodate the AFS systems. The Contractor shall not alter the geometry of the AFS forebody.

• Sketches of the integrated AFS assembly and its major subsystems

• Concepts of the mechanisms to attach and release the AFS at the ESPA Grande port and separate the aeroshell forebody from the backshell to deploy the SmallSat

• Mass and location of ballast to offset the AFS center-of-gravity (CG) from the vehicle centerline to achieve a minimum lift-to-drag ratio (L/D) of 0.25

• Reaction control system delta-V requirements, thruster sizing and orientation, and provisions for propellant storage

• An AFS MEL summarizing the masses of the AFS subsystems with recommended mass growth allowances in accordance with AIAA-S120, Mass Properties Control for Space Systems.

NASA's intent is for the integrated AFS assembly to be conceptual with only the fidelity needed to evaluate mission feasibility and identify risks to mission success. Detailed designs or structural analyses of AFS systems are not intended. The Contractor may leverage past experience with spacecraft systems and aeroshell structures to the maximum extent possible to develop the integrated AFS assembly concept and deliver the required design products.

c) The Contractor shall develop a rough-order-of-magnitude (ROM) cost estimate and approximate development and delivery schedule for the AFS. The ROM cost estimate and schedule shall include design, fabrication, and testing of the primary AFS subsystems, final AFS integration and testing, and delivery to the launch provider. Additionally, the Contractor shall identify long-lead items and opportunities where the Contractor's existing product lines can be leveraged to shorten the overall time to launch readiness.

d) The Contractor shall participate in the following meetings and reviews with NASA. All meetings shall be conducted remotely.

• A Kick-off Meeting, within 5 calendar days of contract award, to review the conceptual design requirements and exchange information

• Weekly meetings to exchange information and provide status on the conceptual design progress

• An AFS Concept Review at which the Contractor shall present the conceptual design results, conducted no later than 5 calendar days prior to the end of the Contract period of performance

3. ARRIVAL Reference Mission

The AFS conceptual design described in this SOW shall be based on the ARRIVAL GTO-based reference mission illustrated in Figure 1. The following sequence of events, identified in Figure 1, comprise the high-level concept of operations for the reference mission.

Event 1: The AFS, attached to the port of an ESPA Grande with a separation mechanism, is delivered into GTO by the launch vehicle. Near GTO apogee, the launch vehicle upper stage delivers the delta-V (perigee lowering maneuver) required to divert the AFS along the flight path necessary to intercept the Earth's atmosphere for the lift-controlled aerocapture maneuver.

Event 2: The AFS is released from the ESPA Grande and continues along the Earth re-entry trajectory using its reaction control system to maintain attitude leading up to Earth atmospheric interface.

Event 3: After a transit of approximately 5 hours, the AFS reaches Earth entry interface at an altitude of 125 km, beginning the aerocapture maneuver, which is accomplished with a single pass through the atmosphere.

Event 4: During atmospheric flight, the AFS angle of attack is trimmed such that the desired lift-to-drag ratio (L/D) is achieved. The AFS onboard guidance determines the optimal bank angle commands to achieve the desired orbit at atmospheric exit. The AFS reaction control system continually adjusts the capsule's attitude, ensuring both guidance commands and stable flight are achieved. From atmospheric entry to exit, the AFS maintains its flight path inside a pre-planned corridor through the Earth's atmosphere, dissipating energy (i.e., velocity), and developing peak heating and dynamic pressure on the aeroshell.

Event 5: After completing approximately 10 minutes of atmospheric flight, the AFS exits the Earth's atmosphere in a lower-energy elliptical orbit with an apoapsis altitude of approximately 500 km - to be reconciled (TBR).

Event 6: Within 15 minutes (TBR) after exiting the Earth's atmosphere, the AFS aeroshell forebody and backshell are separated to expose the SmallSat in its stowed configuration prior to its deployment. The forebody and the backshell re-enter the Earth’s atmosphere for disposal.

Event 7: The SmallSat is deployed into the new, lower energy elliptical orbit. The SmallSat utilizes its attitude control system to attain a stable attitude and prepares for an apogee burn to circularize the orbit (periapsis raise maneuver).

Event 8: When the SmallSat reaches apogee for the first time in the new orbit, its propulsion system delivers the delta-V necessary to conduct the periapsis raise maneuver.

Event 9: When the SmallSat reaches perigee, its propulsion system delivers the delta-V necessary for an apoapsis correction maneuver, which places the spacecraft into the final intended 500 km (TBR) circular orbit.

Figure 1. ARRIVAL GTO-Based Reference Mission Concept of Operations

Upon completion of the nine events, the SmallSat continues in its circular orbit until the flight data acquired throughout the demonstration has been transmitted to ground stations. The flight data include, at a minimum, 6-degree-of-freedom trajectory data acquired by the SmallSat IMU, entry environments measurements (e.g., thermal, pressure) acquired by the NASA-furnished ESI, and on-board imagery gathered throughout the flight from NASA-furnished cameras. The successful transmission of the flight data signifies the end of the demonstration, with the exception of any spacecraft disposal operations necessary in accordance with NASA orbital debris requirements.

4. ARRIVAL Flight System Characteristics

The AFS conceptual design described in this SOW shall be based on the following AFS salient features and functional capabilities to support the ARRIVAL reference mission.

AFS Configuration: The AFS shall be a blunt-body capsule with a 70° sphere-cone forebody geometry.

The preliminary basis of the capsule geometry is illustrated in Figure 2. The AFS capsule must provide the volume to accommodate the SmallSat, the AFS Reaction Control System, wiring harnesses, and ancillary systems required to perform the mission. The AFS shall possess the mass and volume to be accommodated on a single port of an ESPA Grande. The Contractor may alter the geometry of the AFS backshell, with approval from NASA, if necessary to accommodate the AFS systems. The Contractor shall not alter the geometry of the AFS forebody.

Figure 2. ARRIVAL Reference Mission AFS Configuration (notional)

AFS Aeroshell: The aeroshell shall be comprised of a forebody heatshield structure and a backshell structure with mechanical provisions to separate the two structures after completion of the aerocapture maneuver. The backshell structure shall accommodate a separation ring to attach and release the AFS from the ESPA Grande port and incorporate external mechanical interfaces for ground support equipment (GSE) and electrical connections for battery charging and functional tests prior to launch.

The aeroshell structure shall also incorporate the mechanical interface to secure the SmallSat and then deploy it after the forebody and backshell are separated. Devices to sever wiring harnesses between the SmallSat and AFS systems will be required, and depending on the Contractor's SmallSat telecommunications configuration, an antenna(s) mounted to the backshell structure may also be required.

Aerodynamic Lift Provisions: The AFS shall control its flight path during the aerocapture maneuver by modulating the magnitude and/or direction of the entry capsule's aerodynamic lift vector (e.g., bank angle modulation). For this conceptual design, the Contractor shall incorporate provisions for the vehicle's aerodynamic lift to be produced by the capsule flying at an angle-of-attack induced by offsetting the AFS CG from the vehicle centerline.

Thermal Protection Systems: The aeroshell forebody heatshield and backshell shall include Government-furnished thermal protection systems (TPS) to protect the AFS from the aerothermal environments produced during the aerocapture maneuver. The forebody TPS material shall be Conformal Phenolic-Impregnated Carbon Ablator (C-PICA). NASA is considering a variety of candidate backshell TPS materials and will specify the material to be used for this Conceptual Design during the Kickoff Meeting described in Section 2.

Entry System Instrumentation: The Government will furnish the ESI to be incorporated into the aeroshell heatshield and backshell for the ARRIVAL demonstration. The ESI will be comprised of thermal and pressure sensors (the quantities and locations of which are currently being determined) to measure the AFS entry environments during the aerocapture maneuver. A Flight Data System residing

R = 9.58 cm

R = 17.84 cm

30°

67.6 cm

20°

Diameter

103.0 cm

Backshell

Forebody

Notional 12U SmallSat on the SmallSat shall provide power to the ESI and record and store the ESI data that will be transmitted to ground stations near the conclusion of the demonstration.

AFS Reaction Control System: The AFS shall incorporate a reaction control system with the capability to maintain AFS attitude as required after release from the ESPA Grande through the aerocapture maneuver to the point when the aeroshell separates and the SmallSat is deployed.

AFS SmallSat: The ARRIVAL reference mission concept of operations requires the AFS SmallSat to be operational for the full duration of the technology demonstration timeline. The SmallSat shall provide power, avionics and flight instrumentation including an IMU, C&DH, attitude determination and control (including guidance flight software), propulsion, and communications for all mission phases from GTO insertion to data download and orbital debris mitigation (as required). The SmallSat is required to interface with external systems, such as the AFS reaction control system and ESI, to support the mission through the aerocapture maneuver, and then operate in a stand-alone configuration after being released from the aeroshell. The SmallSat shall be accommodated inside the AFS geometry described in Figure 2.

5. Government Furnished Information

The Government will provide the following information to the Contractor within 5 days after contract award.

• The geometry definition of the AFS outer mold line in .stp file format.

• The quantities, locations, accommodation requirements, and data requirements of the NASA-furnished ESI and on-board cameras. Geometry definition files of the ESI pressure sensors in .stp file format will also be provided for the Contractor to include in the AFS conceptual assembly.

• The identified materials, relevant material properties, and material thicknesses for the aeroshell forebody and backshell thermal protection systems.

• Nominal trajectory data for the AFS aerocapture maneuver through the Earth's atmosphere, including time histories of altitude, dynamic pressure, and aerothermal environments.

• Preliminary information regarding the NASA-furnished guidance software to enable the contractor to develop concepts to interface the guidance software with the remaining SmallSat flight software as described in Section 2(a).

6. Deliverables

The Contractor shall summarize the results of the ARRIVAL flight system conceptual design in Microsoft Powerpoint presentation format to support the AFS Concept Review described in Section 2(d).

The Contractor shall update the Powerpoint design package based on feedback from the AFS Concept Review, and provide the final package via e-mail

7. Period of Performance

The period of performance is 90 calendar days from contract award.