The Laser Ranging Interferometer (LRI) instrument on the Gravity Recovery and Climate Experiment (GRACE) Follow-On mission has provided the first laser interferometric range measurements between ...remote spacecraft, separated by approximately 220 km. Autonomous controls that lock the laser frequency to a cavity reference and establish the 5 degree of freedom two-way laser link between remote spacecraft succeeded on the first attempt. Active beam pointing based on differential wavefront sensing compensates spacecraft attitude fluctuations. The LRI has operated continuously without breaks in phase tracking for more than 50 days, and has shown biased range measurements similar to the primary ranging instrument based on microwaves, but with much less noise at a level of \(1\,{\rm nm}/\sqrt{\rm Hz}\) at Fourier frequencies above 100 mHz.
On April 19, 2021, NASA's Ingenuity Mars Helicopter successfully executed humanity's historic first flight on Mars. In the flights that followed, Ingenuity continued to explore the boundaries of what ...was aerodynamically, energetically, and operationally possible, and took on increasingly daring missions in the process. Over time, Ingenuity's mission has evolved from a "Technology Demonstration" of the first rotorcraft to fly on Mars to an "Operations Demonstration" of scientific aerial exploration scenarios on Mars. Ingenuity's activities to date have yielded a rich first-of-its-kind data set and extensive operational experience. This paper describes the Ingenuity Mars Helicopter's operation and technical performance. It details the approach and considerations involved in remotely operating a rotorcraft on Mars from Earth. It presents the performance of the vehicle in the extremely thin Martian atmosphere compared to predicted design values, based on analysis and testing on Earth. The agreement between predicted and observed performance has been excellent. This paper also discusses scientific impacts that Ingenuity Mars Helicopter has been able to contribute to the Mars 2020 Perseverance mission during Ingenuity's Operations Demonstration phase. The performance of the vehicle, the operational experiences and lessons learned, anomalies encountered and their resolutions presented in this paper critically inform the formulation, design, and development of the next generation of advanced aerial rotorcraft platforms for Mars and other extra-terrestrial bodies. 1 1 Copyright 2021 Jet Propulsion Laboratory, California Institute of Technology. Government sponsorship acknowledged. 2 2 The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004).
This paper presents a technology development initiative focused on delivering SmallSats to orbit a variety of bodies using aerocapture. Aerocapture uses the drag of a single pass through the ...atmosphere to capture into orbit instead of relying on large quantities of rocket fuel. Using drag modulation flight control, an aerocapture vehicle adjusts its drag area during atmospheric flight through a single-stage jettison of a drag skirt, allowing it to target a particular science orbit in the presence of atmospheric uncertainties. A team from JPL, NASA Ames, and CU Boulder has worked to address the key challenges and determine the feasibility of an aerocapture system for SmallSats less than 180kg. Key challenges include the ability to accurately target an orbit, stability through atmospheric flight and the jettison event, and aerothermal stresses due to high heat rates. Aerocapture is a compelling technology for orbital missions to Venus, Mars, Earth, Titan, Uranus, and Neptune, where eliminating the propellant for an orbit insertion burn can result in significantly more delivered payload mass. For this study, Venus was selected due to recent NASA interest in Venus SmallSat science missions, as well as the prevalence of delivery options due to co-manifesting with potentially many larger missions using Venus for gravity assist flybys. In addition, performing aerocapture at Venus would demonstrate the technology's robustness to aerothermal extremes. A survey of potential deployment conditions was performed that confirmed that the aerocapture SmallSat could be hosted by either dedicated Venus-bound missions or missions performing a flyby. There are multiple options for the drag skirt, including a rigid heat shield or a deployable system to decrease volume. For this study, a rigid system was selected to minimize complexity. A representative SmallSat was designed to allocate the mass and volume for the hardware needed for a planetary science mission. In addition, a separation system was designed to ensure a clean separation of the drag skirt from the flight system without imparting tipoff forces. The total spacecraft mass is estimated to be 68 kg, with 26 kg of useful mass delivered to orbit for instruments and supporting subsystems. This is up to 85% more useful mass when compared to a propulsive orbit insertion, depending on the orbit altitude. Key to analyzing the feasibility of aerocapture is the analysis of the atmospheric trajectory, which was performed with 3 degree-of-freedom simulations and Monte Carlo analyses to characterize the orbit targeting accuracy. In addition, aerothermal sizing was performed to assess thermal protection system requirements, which concluded that mature TPS materials are adequate for this mission. CFD simulations were used to assess the risk of recontact by the drag skirt during the jettison event. This study has concluded that aerocapture for SmallSats could be a viable way to increase the delivered mass to Venus and can also be used at other destinations. With increasing interest in SmallSats and the challenges associated with performing orbit insertion burns on small platforms, this technology could enable a new paradigm of planetary science missions.
This packaging design approach can help heritage hardware meet a flight project's stringent EMC radiated emissions requirement. The approach requires only minor modifications to a hardware's chassis ...and mainly concentrates on its connector interfaces. The solution is to raise the surface area where the connector is mounted by a few millimeters using a pedestal, and then wrapping with conductive tape from the cable backshell down to the surface-mounted connector. This design approach has been applied to JPL flight project subsystems. The EMC radiated emissions requirements for flight projects can vary from benign to mission critical. If the project's EMC requirements are stringent, the best approach to meet EMC requirements would be to design an EMC control program for the project early on and implement EMC design techniques starting with the circuit board layout. This is the ideal scenario for hardware that is built from scratch. Implementation of EMC radiated emissions mitigation techniques can mature as the design progresses, with minimal impact to the design cycle. The real challenge exists for hardware that is planned to be flown following a built-to-print approach, in which heritage hardware from a past project with a different set of requirements is expected to perform satisfactorily for a new project. With acceptance of heritage, the design would already be established (circuit board layout and components have already been pre-determined), and hence any radiated emissions mitigation techniques would only be applicable at the packaging level. The key is to take a heritage design with its known radiated emissions spectrum and repackage, or modify its chassis design so that it would have a better chance of meeting the new project s radiated emissions requirements.
