The National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) is in the early stages of developing a mission design, project implementation plan, and procurement strategy that could potentially lead to an Earth aerocapture technology demonstration mission. NASA LaRC is hereby soliciting information from potential sources with the capabilities to provide spacecraft systems and mission operations for the mission.

The mission would demonstrate aerocapture at Earth as a precursor to using the technology for future planetary science missions. Aerocapture technology reduces the required capability and mass of a spacecraft propulsion system, lowering the launch vehicle payload mass or enabling more capacity for science instruments, and is particularly beneficial for missions to the Solar System's ice giant planets [1]. The demonstration mission is intended to focus on key objectives necessary to mature the technological readiness of aerocapture including vehicle aerodynamics, flight dynamics, guidance, navigation and control, and mission operations. Flight data will be acquired during the demonstration and used to improve and validate tools to design and plan future missions.

NASA is considering two concepts for the mission, both of which use a small entry capsule (referred to as the Aerocapture Flight System, or AFS) to execute the aerocapture maneuver. The AFS is comprised of an aeroshell, reaction control system, other ancillary systems, and a SmallSat that is released into Earth orbit. The first mission concept utilizes a Geostationary Transfer Orbit (GTO) as an initial state for the AFS, which is deployed into GTO from an Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA). In the second concept, the AFS is released on an Earth intercept trajectory from a spacecraft returning from a lunar mission. A preliminary concept of operations (ConOps) for a GTO-based aerocapture demonstration is illustrated in Figure 1 (attached). Details shown regarding orbit altitudes are for reference only, and will continue to be resolved (TBR) in upcoming design trades.

Referring to Figure 1, the preliminary high-level mission ConOps and sequence of events is as follows. The sequence of events is for reference and context only to support the vendors' responses to this request for information, and will continue to be updated as NASA LaRC progresses through the early stages of mission design.

1. The AFS, attached to the port of an ESPA Grande with a separation mechanism, is delivered and released into GTO by the launch vehicle. The AFS continues in GTO while using its reaction control system to maintain attitude during preparations for the aerocapture maneuver. NASA's intention is for the AFS to complete less than two full orbits before beginning the aerocapture maneuver.
2. Near GTO apogee, the AFS reaction control system delivers the delta-V required to divert the capsule along the flight path necessary to intercept the Earth's atmosphere and initialize the aerocapture maneuver.
3. The AFS reaction control system continually adjusts the capsule's attitude, utilizing the vehicle's aerodynamic lift to maintain its flight path inside a pre-planned corridor through the Earth's atmosphere with a periapsis of approximately 65 km (TBR).
4. After completing the atmospheric flight, the AFS exits the Earth's atmosphere in an elliptical orbit with an apoapsis of approximately 500 km (TBR).
5. Within 15 minutes (TBR) after exiting the Earth's atmosphere, the forward heatshield of the AFS aeroshell is jettisoned and a SmallSat is released into the new elliptical orbit. The SmallSat utilizes its attitude control system to attain a stable attitude and prepares for an apogee burn to circularize the orbit.
6. When the SmallSat reaches apogee for the first time, its propulsion system delivers the delta-V necessary to circularize the orbit at an altitude of 500 km (TBR).
7. The SmallSat continues in its circular orbit until the flight data acquired throughout the demonstration has been transmitted to ground stations. Successful transmission of the flight data signifies the end of the demonstration, subject to any spacecraft disposal operations necessary in accordance with NASA orbital debris requirements [2, 3].

The salient features and high-level functional requirements of the AFS that are envisioned to support the mission’s preliminary concept of operations are as follows. Since NASA is in the early stages of mission and system design, these features and requirements are subject to change as the design matures. The information is provided herein as a reference for vendors to consider when evaluating the mission concept and assessing the capabilities that vendors may contribute to the demonstration mission in response to this request for information.

AFS