Extended Mission Technology Demonstrations Using the ASTERIA

Extended Mission Technology Demonstrations Using the ASTERIA Spacecraft Lorraine Fesq, Patricia Beauchamp, Amanda Donner, Mary Knapp Rob Bocchino, Brian Kennedy, Swati Mohan, David MIT Haystack Observatory Sternberg, Matthew W. Smith, Martina Troesch 99 Millstone Rd. Jet Propulsion Laboratory, California Institute of Westford, MA 01886 Technology (607) 425-9617 4800 Oak Grove Dr. [email protected] Pasadena, CA 91109 (818) 393-7224, 354-0529, 393-8636, 354-8175, 354- 6327, 354-5305, 354-6685 354-1319, 354-8088 {Lorraine.M.Fesq, Patricia.M.Beauchamp, Amanda.Neufeld, Robert.L.Bocchino, Brian.M.Kennedy, Swati.Mohan, David.C.Sternberg, Matthew.W.Smith, Martina.I.Troesch}@jpl.nasa.gov

Abstract— ASTERIA (Arcsecond Space Telescope Enabling be our closest exoplanetary neighbor orbiting a Sun- Research In Astrophysics) is a CubeSat space telescope like star. currently operating in low-Earth orbit. It is expected to remain in orbit at least through October 2019. Developed as a These demonstrations will provide in-flight testing of new technology demonstration mission under the JPL Phaeton autonomy technologies, maximize the scientific potential of this Program for training early-career engineers, ASTERIA has operational spacecraft, and provide additional characterization achieved sub-arcsecond pointing stability and milliKelvin of hardware for future small satellite missions using similar thermal stability over 20-minute observations. These subsystems. capabilities—unprecedented in a CubeSat platform—have enabled photometric precision better than 1000 ppm/min while TABLE OF CONTENTS observing nearby bright stars (V<6). 1. INTRODUCTION ...... 1 Following the second extended mission, we are now using the 2. BACKGROUND ...... 2 spacecraft in its third extension as a platform to demonstrate additional capabilities as well as continue science observations. 3. EXTENDED MISSION ACTIVITIES ...... 4 This project will perform the following four well-focused 4. SUMMARY ...... 8 activities that will raise the technology readiness of key ACKNOWLEDGEMENTS ...... 9 spacecraft technologies. REFERENCES ...... 9 1. Shift the paradigm to operate spacecraft from open- BIOGRAPHIES ...... 9 loop commanding to closed-loop command execution: We will introduce “task networks” (tasknets) which 1. INTRODUCTION allow simpler commanding and more robust onboard execution. ASTERIA (Arcsecond Space Telescope Enabling Research 2. Demonstrate onboard orbit determination in Low In Astrophysics) is a CubeSat space telescope currently Earth Orbit (LEO) using autonomous navigation operating in low-Earth orbit. It is expected to remain in orbit (Autonav) without GPS: This activity will demon- through at least October 2019. Developed as a technology strate a fully independent means of spacecraft orbit determination for Earth orbiters using only passive demonstration mission under the JPL Phaeton Program for imaging. training early career engineers, ASTERIA has achieved sub- 3. Collect data on ASTERIA that will feed into future arcsecond pointing stability and milliKelvin thermal missions by characterizing the spacecraft pointing jit- stability over 20-minute observations [1][2]. These ter as a function of target brightness, reaction wheel capabilities—unprecedented in a CubeSat platform—have speed, controller gain, and number of guide stars. enabled photometric precision better than 1000 ppm/min 4. Perform ASTERIA extended mission science: while observing nearby bright stars (V<6). ASTERIA has demonstrated unprecedented photometric precision for a CubeSat mission. The space- JPL now has extended the ASTERIA mission beyond its craft is uniquely suited to perform long-term moni- prime mission and two short extended missions to build on toring of stars such as alpha Centauri for small transiting planets. The discovery of a transiting Earth- ASTERIA’s outstanding science results and to perform four sized planet around alpha Cen A and/or B would be targeted activities that will raise the readiness of key of the highest scientific value as such a planet would technologies. Specifically, the extended mission aims to achieve the following:

1. Shift the paradigm to operate spacecraft from open- 90-day primary mission. As of 1 February 2018, the mission loop commanding to closed-loop command execu- satisfied Level 1 Requirements by achieving the following tion. Introduce task networks (“tasknets”) to allow milestones: simpler commanding and more robust on-board execution. ASTERIA will continue to carry out scientific • Demonstrating optical line-of-sight pointing stability of observations to demonstrate the effectiveness of these 0.5 arcsecond RMS over 20 minutes (compared to the tasknets and the applicability of this approach for requirement of 5 arcseconds). increasing the efficiency and robustness of future space missions. • Demonstrating focal plane temperature stability better 2. Demonstrate onboard orbit determination in Low than ±10 milliKelvin over 20 minutes. Earth Orbit (LEO) using autonomous navigation (“Autonav”) without GPS. This activity will demon- • Demonstrating the ability to collect windowed images strate a fully-independent means of spacecraft orbit and produce stellar flux data in a cadence that permits determination for Earth orbiters using only passive photometric study of nearby bright stars. imaging. This capability will enable future missions to navigate in GPS-denied environments and with a more The level of pointing and thermal control obtained by robust sensor suite. ASTERIA is unprecedented compared to other missions in a 3. Collect data on ASTERIA that will feed into future similar mass category (see Figure 1 and Figure 2). missions. Characterize the spacecraft pointing jitter as a Recent processing of data obtained during the mission so far function of target brightness, reaction wheel speed, has demonstrated the capability to detect the known transit controller gain, and the number of guide stars. These of 55 Cancri e, a super-Earth exoplanet (2 R ) orbiting a data will yield additional insights into the contribution Earth nearby bright Sun-like star (V = 5.95). ASTERIA’s of jitter to the ASTERIA photometry and inform the photometric precision is of sufficient quality that this 410 feasibility of other astrophysics small satellite missions ppm transit was detected at a significance of 3σ (see Figure for which jitter control is an enabling technology. 3) [3]. This marks the first time that a CubeSat has observed 4. Perform ASTERIA extended mission science. an exoplanet transit and offers a proof of concept that ASTERIA has demonstrated unprecedented photomet- meaningful astrophysical measurements—including ric precision for a CubeSat mission. The spacecraft is exoplanet detections—are feasible using a CubeSat uniquely suited to perform long-term monitoring of platform. stars such as alpha Centauri for small transiting planets. The discovery of a transiting Earth-sized planet The scientific objective of the current mission is to conduct around alpha Cen A and/or B would be of the highest opportunistic observations for the detection of small scientific value as such a planet would be our closest transiting exoplanets (one to several Earth radii) by exoplanetary neighbor orbiting a Sun-like star. observing HD 219134 and the alpha Centauri system. Additional observations also can be achieved including Transits of small exoplanets are not detectable from the targeting other spacecraft and performing Earth Science ground due to the blurring effects of Earth’s atmosphere but weather phenomena imaging. With additional funding they offer rich science potential. Transit light curves offer a and a further extension, the spacecraft could be pro- direct measurement of exoplanet radius, constraining grammed to detect and respond to transient events. planetary composition. Small planets transiting bright, nearby stars are the best candidates for follow-up atmospheric characterization via transit spectroscopy by These activities will interleave with one another to exploit other observatories (e.g. HST, JWST). the use of the spacecraft over the timeframe of the extension. In addition to maximizing the scientific potential ASTERIA’s main target is HD 219134, a nearby star with of this operational spacecraft, this extension will provide two known transiting exoplanets, designated b and c [4]. additional context for future small satellite astrophysics This system is compelling for ASTERIA because it hosts missions. These missions include (1) missions considered two additional exoplanets not known to transit. Designated under NASA’s Astrophysics Science SmallSat Studies d and f, these planets were discovered by radial velocity solicitation (NNH18ZDA001N-AS3) and (2) missions measurements and are small “mini Neptune” planets in 22- considered under NASA’s recent AO for Astrophysics and 46-day orbits respectively [5]. ASTERIA has observed Explorers. The AO includes Missions of Opportunity for time windows corresponding to the possible d and f transits. CubeSats/SmallSats (NNH18ZDA014L). Data from those observations are currently being analyzed by the science team to determine whether a transit of either

planet occurs. 2. BACKGROUND ASTERIA was deployed from the International Space ASTERIA has also performed test observations of alpha Station into low-Earth orbit on 20 November 2017 to start a Centauri and achieved excellent photometric precision (125 ppm/minute).

Figure 1. ASTERIA pointing stability compared to other spacecraft across a range of launch mass. ASTERIA achieved pointing stability over 20 minutes of 0.5 arcseconds RMS, compared to a requirement of 5 arcseconds RMS. [1]

Figure 2. ASTERIA focal plane temperature stability compared to other spacecraft across a range of launch mass. ASTERIA achieved focal plane temperature stability over 20 minutes of ±0.005 K (measured at a single point), compared to a requirement of ±0.010 K. [2]

Figure 3. ASTERIA 55 Cancri e transit light curve. The horizontal axis shows planet orbital phase (0 is mid-transit) and the vertical axis shows relative flux. Gray points are 1-minute cadence ASTERIA data; black points are 30- minute time bins. Error bars represent the quadrature sum of the 1-minute measurement errors of points in each 30- minute bin. The red line is a transit model fit to the data. There are 526 minutes of observation collected over 62 orbits represented in this plot. ASTERIA science team member Brice-Olivier Demory (University of Bern) performed the data reduction and model fitting using community-standard Markov Chain Monte Carlo (MCMC) techniques.

3. EXTENDED MISSION ACTIVITIES for ASTERIA but for future small satellites by characterizing jitter; and (4) to continue ASTERIA’s high-risk, high- The current mission extension will allow NASA and JPL to reward exoplanet science observation campaign. continue using the ASTERIA spacecraft for technology Aerodynamic drag analysis shows that ASTERIA’s orbit is demonstrations and for additional observations. The goals of viable until late 2019 (see Figure 4). Furthermore, this extension are (1) to demonstrate closed-loop housekeeping telemetry shows that the spacecraft commanding using tasknets for robust command execution; subsystems remain healthy and can continue to operate for (2) to demonstrate on-board orbit determination using at least another year. The four extended mission activities Autonav for operation in GPS-constrained/denied are described in additional detail in the following sections. environments; (3) to improve pointing performance not only

Figure 4. ASTERIA lifetime calculation. This plot shows propagated orbit apogee, perigee, and eccentricity for ASTERIA as a function of time as calculated by STK. Deorbit occurs in October 2019. 4

On-Board Task Network Execution 2. When scheduling the tasks in a tasknet, MEXEC can account for expected conditions during the ASTERIA currently is operated using simple, time-based planned activity. For example, MEXEC can ask command sequences that are generated on the ground and flight software (FSW) to compute the longest safe uplinked almost daily to the spacecraft. This commanding duration for an observation, based on expected approach is limited in a number of ways: available power, and it can set the task duration ac- • ASTERIA does not always respond correctly and cordingly. completely to commands due to now-known idio- 3. Tasknets can specify contingencies, i.e., actions to syncrasies. For example, the camera does not al- take in case of unanticipated conditions such as ways initialize correctly when commanded into fi- command failures. For example, if a camera con- ne control mode. As a workaround, the command figuration command fails, MEXEC can retry the sequences are constructed by ground operators command until either the camera is properly con- with multiple camera reinitialization commands to figured or the observation window has ended. better ensure that the camera is turned on and in a good state in time for the observations. These re- MEXEC enables significantly more autonomous behavior dundant commands are included and executed even than is currently feasible for ASTERIA and other CubeSats if the camera responded correctly after the first by closing the loop onboard and checking that expected command. conditions have been met. This additional autonomy can ensure increased science return for future CubeSats, • The conditions of the spacecraft such as tempera- SmallSats, and even larger spacecraft. tures are not always predictable over the course of the day’s-worth of commands contained in a se- The mission is integrating MEXEC with the ASTERIA quence. For example, to determine set points of the FSW so that ground operators can use task networks instead payload active thermal control system, operators of time-based sequences to command the spacecraft. The must estimate the temperature profiles through state model and the task preconditions will be simple: the multiple eclipses, including consideration of what on-board state will track the status of each command issued, hardware is powered on and for how long. and the precondition of each task will be that the previous task succeeded. The goal is to supplement the existing • The battery state-of-charge is estimated very sequencer with an alternate way of scheduling commands, at conservatively so as not to cause long-term battery about the same level of capability that currently exists, but degradation. As a result, some science opportuni- using the tasknet mechanism to demonstrate the viability of ties are lost when there is still sufficient charge in the technology on orbit. the battery that was not utilized. This experiment will represent the first use of MEXEC • If any commands are not executed correctly or if tasknets to command a spacecraft in flight. It will prove the the predictions were not sufficiently accurate, the feasibility of using MEXEC in a flight environment. It will sequence will be stopped and the remainder of the also prepare the way for future projects to use MEXEC with day’s science observations are aborted, losing the more complex state models and autonomous spacecraft rest of the observations and wasting precious ob- behavior (e.g., modeling power and temperature, adjusting serving time. observation parameters to current power and temperature conditions, and robustly handling command failures). JPL has developed a generic smart executive called MEXEC (Multi-spacecraft EXECutive) [6]. Like a Running MEXEC on board the ASTERIA spacecraft will command sequencer, MEXEC issues commands according consume resources (CPU cycles and memory). The to instructions provided from the ground. However, instead integration and test (I&T) team will run tests on the of executing command sequences based on pre-determined ASTERIA testbed to verify that the additional resource use time-stamps, MEXEC runs task networks, or tasknets. does not interfere with ASTERIA operations. The operators Tasknets provide the following key capabilities not found in will run all tasknets on the testbed prior to uplink to ensure traditional sequences: proper execution; this is analogous to how sequences are currently tested. 1. Before issuing any command in a tasknet, MEXEC can examine the system state and apply precondi- Autonomous Navigation Experiment tions to determine whether the command is safe to execute. For example, before starting a science ob- The Autonomous Navigation (Autonav) experiment will servation, MEXEC can check that the camera pow- demonstrate the ability of a software subsystem to provide a er state is consistent with the estimated state, so it fully independent means of spacecraft orbit determination is safe to proceed. while in Earth orbit. This independence is based on passive optical observations of asteroids, comets or other bodies— possibly including other spacecraft—that are following 5 known trajectories. This subsystem provides robustness statistical confidence of the resulting orbit determination against unexpected outages in the GPS constellation, USAF solutions. Some redesign of the Autonav software will be tracking assets, or other ground assets typically needed to required, primarily managing the image data transport to the navigate an Earth orbiter. Autonav software. Autonav command interfaces will also need to be designed and implemented, as well as specific As with all objects in low-Earth orbit (LEO), ASTERIA is telemetry and event recording. currently being tracked by the Joint Space Operations Command (JSpOC). The JSpOC methodically fits the After camera characterization, planning and software ASTERIA trajectory data and publishes two-line element redesign, the initial integration and ground testing can sets (TLEs) of the ASTERIA orbit. The ASTERIA project begin. Integration and testing will be completed and the then uses the latest TLE to predict ground station passes and updated flight software will be uploaded to ASTERIA and to plan observations. Since TLEs are limited predictors of a run through initial flight tests. Any remaining integration low-Earth orbit, and because the JSpOC is not always able and testing will be completed and the Autonav experiment to provide timely TLE updates, we will add an autonomous operated over a two- to three-month period. During this navigation system to ASTERIA in order to demonstrate a time, it will execute routine imaging sessions on a frequent reduced reliance on the TLEs. ASTERIA has experienced basis to acquire optical navigation data. These image several periods of significantly reduced data downlink sessions will re-orient the spacecraft to point the camera at efficiency due to suspected TLEs inaccuracies. ASTERIA near-Earth asteroids, distant bright asteroids and possibly does not have a working GPS, so Autonav would provide an satellites in geosynchronous orbit. Multiple images of each alternative means for performing orbit determination, target will be taken, and these images will be processed to mitigating periodic TLE issues and increasing science data determine the inertial direction from the spacecraft to each return. Demonstrating Autonav would also carry similar target. On a daily or weekly basis, Autonav will perform benefits for future small satellites in LEO and will orbit solutions using the inertial direction data and downlink demonstrate the ability to autonomously navigate spacecraft its latest estimate of the current and future ASTERIA orbit. orbiting other bodies. ASTERIA will also downlink reports of the data extracted from the camera imagery, and some (if not all) of the JPL’s “Autonav” software from the 2005 Deep Impact camera imagery acquired during each imaging session. The mission is designed to provide autonomous optical downlinked data will be reprocessed on the ground for navigation based on asteroid images taken with an onboard quality assurance, and then compared against the TLEs. A camera. Software similar to this was previous flown on the report on the theoretical/practical Autonav effectiveness and Deep Space 1 mission, launched in 1998. This software is predictive performance will be produced at the completion capable of identifying the pixel signatures of distant of the future extended mission(s). asteroids in a camera image, rendering the signatures into a set of navigation observations and determining the Jitter Observations and Analysis spacecraft orbit based on a series of those observations. The A very exciting aspect of the ASTERIA mission is the low original intent of this software was to perform orbit pointing jitter values that have been demonstrated under determination on spacecraft in interplanetary orbits, whose ASTERIA’s fine pointing control mode [1]. Jitter is the orbital periods are much longer than for low Earth orbits, high-frequency attitude motion of the satellite over a and where the dynamic forces acting on the spacecraft are specified time scale, such as the camera exposure time. more relaxed. The extended mission will investigate the Increased jitter (i.e., increased motion of the camera relative applicability and performance of this type of autonomous to the incident light during the image exposure) leads to navigation system to the LEO case to enable future blurring as the light from the star is distributed over more spacecraft to determine their orbits without GPS or other pixels on the camera. external navigation aids. The main source of jitter on ASTERIA, and on many Extended mission activities will cover camera calibration, CubeSats, is the reaction wheels. The reaction wheels are mission design, software redesign and initial software physically rotating parts, which impart disturbance forces integration and test of Autonav capabilities. Images from the and torques that cause the spacecraft to rotate. Additionally, 9x11 degree FOV camera onboard ASTERIA will be the wheels operate continuously, so the disturbances occur studied to determine appropriate exposure durations for the continuously. By contrast, thruster systems on other experiment and feasibility of resolving particularly dim CubeSats such as the JPL Lunar Flashlight mission targets. Select images will be processed on the ground using contribute to jitter intermittently [7]. The magnitude and the Autonav image processing software to confirm direction of the reaction wheel disturbances is a function successful data reduction. Next, plans for target acquisition predominantly of their rotational speed. Prior to launch, the (2-4 per orbit) over several orbits will be developed given ASTERIA mission performed analysis to estimate the in- the ASTERIA operating constraints and attitude control flight jitter. The analysis used reaction wheel models subsystem capabilities, and implemented into flight provided by JPL’s Small Satellite Dynamics Testbed commands and sequences. These plans will be also studied (SSDT) [8]. Jitter has a strong impact on all aspects of the using statistical covariance analysis to calculate the formal system architecture, and vendors generally do not provide 6 enough information to understand if a given unit is useful third set of three orbits will use two-stage fine pointing for a particular application. Operationally, high jitter may control (reaction wheels plus piezo stage closed loop result in lower or higher photometric precision, depending control). Multiple observations per mode will allow for on the target brightness. characterization of the impact of thermoelastic changes from orbit to orbit. Thermal control will be turned off between This experiment, which is planned for completion in the each set of three observations for at least 5 orbits so that first quarter of FY19, characterizes the following sources of each set starts from the same initial thermal conditions. The jitter on the ASTERIA spacecraft: target stars will be chosen such that they are in different regions of the sky to capture impact of the variance of the • Jitter caused by the coarse stage control, performed star tracker fields on the jitter. by the Blue Canyon Technologies XACT attitude control unit; We will compare the jitter values from the simulations to those measured in the flight operational environment. The • Residual jitter caused by the fine stage (piezo- same set of measurements can be mined for additional stage) control. information to provide flight to ground validation of the SSDT simulation, such as absolute pointing accuracy, Fully characterizing the jitter in the flight environment will pointing accuracy while slewing, and environmental benefit all SmallSat missions planned and in development, disturbances. The evaluation of the space vs. ground especially those devoted to photometric/spectroscopic differences will allow the JPL SSDT simulation to be tuned astrophysics applications. With 6U CubeSats being poised to better represent flight. These data can then be used by all to become the workhorses of SmallSat astrophysics, and other projects that use these wheels or similar models, ASTERIA being the only 6U operational mission that can improving their models and increasing their knowledge of perform the measurements described here, the jitter testing their system capabilities. campaign is directly applicable to many future missions. One such mission is SPARCS (a NASA-funded 6U with a New Science Observations JPL-supplied camera, currently in development). The results of this experiment will inform the optical ASTERIA has demonstrated unprecedented photometric prescription, science performance, and concept of precision for a CubeSat mission. To date, ASTERIA has operations for SPARCS. Further, NASA has released a call focused on monitoring HD 219134 during the predicted for SmallSat concepts. This call may result in SmallSat transit windows of planets f and d. Full coverage of the 3- astrophysics science missions flying in the 2025 timeframe sigma transit windows of each planet have been completed (NNH18ZDA014L). The results of this jitter and in October 2018. For this mission extension, ASTERIA’s photometric characterization will be crucial for all of these science goals will shift from follow-up of previously- upcoming missions. detected HD 219134 planets to discovery of as-yet unknown additional planets in the system. For the characterization of the coarse stage control (reaction wheels only), the jitter on ASTERIA will be characterized ASTERIA will monitor HD 219134 with the goal of primarily as a function of wheel speed. The satellite will be detecting additional small transiting planets in longer period pointed at a designated star of known brightness. Jitter will orbits than known transiting planets b and c. HD 219134 then be measured by capturing a series of images while the resembles compact multiple systems discovered by the wheel speed bias is varied over the entire range in Kepler mission. Based on the planets discovered to date in increments of approximately 500 rpm. The experiment will this system, it is not “dynamically packed,” meaning that be repeated with several different star fields, each with a there are stable orbits available for additional planets. target star of different brightness and a range of guide star ASTERIA is uniquely suited to characterize this system in magnitudes. Analysis of the set of data will enable the detail and potentially discover completely new transiting determination of the optimal wheel speed bias setting to planets. Small (Earth-sized) planets in this system are choose as a function of star brightness. This will enable extremely difficult, if not impossible, to detect from the ASTERIA to set up the spacecraft to minimize jitter and ground due to atmospheric effects. Space-based telescopes maximize photometric performance. are highly oversubscribed and therefore not available to perform long-term monitoring of a single star. The jitter characterization for the fine stage control (reaction wheels plus piezo stage) consists of observing multiple stars ASTERIA’s second observation target is alpha Centauri, a with magnitudes from approximately V = -1 to V = 7. triple star system containing the two closest sun-like stars to ASTERIA will observe each star for three sets of three the solar system (alpha Cen A and B). A recent ASTERIA consecutive orbits. The first set of three orbits will use test observation of alpha Centauri yielded photometric reaction wheels only (coarse control). The second set of precision of 125 ppm/minute, sufficient to detect planets three orbits will use reaction wheels with closed loop close to Earth size around either alpha Cen A or B. As with feedback from the focal plane. In this mode, the XACT HD 219134, ASTERIA is uniquely suited to perform long- receives information about centroid motion from the focal term monitoring of alpha Centauri for small transiting plane, but the piezo stage is not used to compensate. The planets. The discovery of a transiting Earth-sized planet 7 around alpha Cen A and/or B would be of the highest 4. SUMMARY scientific value as such a planet would be our closest exoplanetary neighbor around a Sun-like star. The ASTERIA mission extension described in this paper offers several benefits that derive from the use of an In [9], the authors reported a radial velocity detection of a existing, well-functioning, orbiting spacecraft. The small planet orbiting alpha Cen B (alpha Cen B b), but this extension provides a unique opportunity to demonstrate detection has since been called into question [10]. A HST autonomy technologies that will provide benefits not only to transit follow-up campaign yielded no detection of alpha the ASTERIA mission but also to future NASA spacecraft. Cen B b [11]. The HST campaign did capture a single transit-like event, which provides speculative evidence that The tasknet demonstration will improve the efficiency and a small planet in a longer period orbit (>3 days) may exist, reduce cost for future projects, especially those that are but further observations are needed. planning to use the same flight software framework (F Prime). These include NASA’s Lunar Flashlight and HD 219134 and alpha Centauri are complementary targets NEAScout CubeSat missions, and the Mars Helicopter. since HD 219134 is in the northern celestial hemisphere and alpha Centauri is in the south. ASTERIA can therefore The Autonav experiment will showcase the ability of a efficiently toggle back and forth between observations of spacecraft to determine its own position in space by these two stars because the portion of ASTERIA's orbit that passively observing objects such as asteroids, comets, and is in Earth's shadow (when observations can be performed) even other spacecraft. This will demonstrate robustness alternates between the Northern hemisphere and the against unexpected outages in the GPS constellation, United Southern hemisphere on a timescale of a few weeks. During States Air Force (USAF) tracking assets, or other ground the extended mission, ASTERIA will observe HD 219134 assets needed for navigation in Earth orbit. The Autonav and alpha Centauri in a series of multi-day continuous experiment on board the ASTERIA spacecraft not only will observation runs, similar to observation campaigns in the demonstrate the ability of a spacecraft in Earth orbit to current extended mission to target the transit windows of autonomously determine its own orbital trajectory entirely HD 219134 f and d. Between runs, image data will be without the benefit of GPS data or tracking data processed downlinked. by ground elements, it also will demonstrate the capability for a Cubesat/Smallsat class mission to perform its own As ASTERIA transitions from transit follow-up to onboard navigation functions. This capability would enable discovery space, the scheduling of observations is less large numbers of these spacecraft to fly in deep space driven by time-critical windows, providing more flexibility without relying on the DSN for tracking and for ground to accommodate other activities. The timing and duration of personnel to perform navigation, thus reducing operational observation runs will be coordinated with other extended costs. The capability also is easily extrapolated to larger mission needs (stellar observations for jitter characteriza- Discovery/New Frontiers/Flagship missions. tion, full frame images for autonav, flight software updates, etc.) by the project manager and the science team. The three The jitter characterization will allow for the correlation of technology experiments will produce the following minor ground testing to in-flight performance, leading to a better impacts to science observations: understanding of on-orbit jitter performance, particularly when using commercial off-the-shelf (COTS) components a) The tasknet experiment will require a new software frequently found in small satellite missions. This upload. Once uploaded, this experiment will be ex- understanding will produce refined estimates for pointing ecuted on a non-interfering basis with science ob- performance and science return for the next generation of servations. Tasknets will demonstrate a new com- spacecraft, such as NASA’s SPARCS mission. mand and execution approach without any re- strictions on targets, so science observations will This extended mission also provides an opportunity to not be impacted during execution of this experi- achieve new science. Current science goals have shifted ment. from follow-up of previously detected planets to discovery of as-yet unknown additional planets. ASTERIA is uniquely b) Autonav will require a new software upload as well suited to perform long-term monitoring required of objects as image capture of selected targets. Two to four such as HD 219134 to potentially discover completely new observations of small bodies and possibly other transiting planets. Additional science goals could be spacecraft over several orbits will be required peri- achieved including pointing the camera at the Earth to odically during the extension. observe weather phenomenon. Further, the spacecraft could be programmed to detect and respond to transient events as c) The Jitter experiment requires a minor software a demonstration of a sensor web element. Although all adjustment and image capture of selected targets. demonstrations are coordinated and interleaved, each Some of these targets could include nominal sci- technology experiment is proceeding independently of the ence observations. The science team and the jitter others with separate schedules, milestones and success experimenters will work together to pick the targets criteria. Resource constraints, such as time on the ASTERIA required to perform the jitter analysis. testbed, new software uploads to the spacecraft, and 8 observations, are managed to avoid conflict. Results of these [10] Rajpaul, V., Aigrain, S., and Roberts, S., “Ghost in experiments are expected in the Summer of 2019. the time series: no planet for Alpha Cen B”, Monthly Notices of the Royal Astronomical Society, Vol. 456, no. 1, pg. L6-L10, 2015. ACKNOWLEDGEMENTS [11] Demory, B., Ehrenreich, D., Queloz, D., et al., Part of the research was carried out at the Jet Propulsion “Hubble Space Telescope search for the transit of Laboratory, California Institute of Technology, under a Earth-mass exoplanet Alpha Centauri B b”, Monthly contract with the National Aeronautics and Space Notices of the Royal Astronomical Society, Vol. 450, Administration. no. 2., pg. 2043-2051, 2015.

BIOGRAPHIES REFERENCES Lorraine Fesq is the Project [1] Pong, C., “On-Orbit Performance & Operation of Manager of the ASTERIA mission the Attitude & Pointing Control Subsystems on and serves as the Chief Technologists ASTERIA”, 32nd Annual AIAA/USU Conference on for the Systems Engineering Division Small Satellites, 2018. at the Jet Propulsion Laboratory, California Institute of Technology. [2] Smith, M., Donner, A., Knapp, M., et al., “On-Orbit She has over 30 years of aerospace Lessons Learned from the ASTERIA Space experience that spans industry, Telescope Mission,” 32rd Annual AIAA/USU government and academia, has worked all mission phases Conference on Small Satellites, 2018. of spacecraft development. Lorraine has received a NASA Public Service Medal for her work on the Chandra X-ray [3] Knapp, M., et al., 2018 (in preparation). Observatory, and a NASA Exceptional Achievement Medal for advancing the Fault Management discipline [4] Gillion, M., Demory, B., Van Grootel, V., et al., within NASA. Lorraine taught in the Aero- “Two massive rocky planets transiting a K-dwarf nautics/Astronautics department at MIT and worked on 6.5 parsecs away,” Nature Astronomy, Vol. 1, no. 3, multiple spacecraft projects at TRW and Ball Aerospace. 0056 (2017). She received her B.A. in Mathematics from Rutgers [5] Vogt, S., Burt, B., Meschiari, S., et al., “Six Planets University and her M.S. and Ph.D. in Computer Science Orbiting HD 219134,” The Astrophysical Journal, from the University of California, Los Angeles. Vol. 814, no. 1 (2015). Patricia M. Beauchamp is currently [6] Vandi, V., Gaines, D., Rabideau, G., et al., the Chief Technologist for the “Autonomous Science Restart for the Planned Engineering and Science Directorate Europa Mission with Lightweight Planning and at the Jet Propulsion and also on the Execution.” International Workshop on Planning NASA Planetary Science Division and Scheduling for Space (IWPSS), 2017. Technology Team (PESTO). She is on the executive committee of the Outer [7] Lai, P., Sternberg, D., Haw, R., et al., “Lunar Planet Assessment Group and has Flashlight CubeSat GNC System Development for been responsible and/or involved in developing Lunar Exploration”, International Astronautical technology plans for the Outer Planets, Venus and Small Congress, 2018. Bodies Assessment Groups. Her previous JPL assignments include serving as Manager of the Planetary [8] Sternberg, D., Pong, C., Filipe, N., et al., “Jet Instrument Development Office, Leader of the Center for Propulsion Laboratory Small Satellite Dynamics In-Situ Exploration and Sample Return (CISSR), and Testbed Simulation: On-Orbit Performance Model Project Manager for the MICAS Instrument on DS1. She Validation”, Journal of Spacecraft and Rockets, Vol. is the recipient of the JPL Explorer, many NASA Group 55, no. 2, pg. 322-334, 2017. Achievement Awards, SGV Woman of Achievement in Science and AESC Recognition of Excellence. Pat [9] Dumusque, X., Pepe, F., Lovis, C. et al., “An Earth- received a B.S. in Chemistry and B.A. in Mathematics Mass Planet Orbiting Alpha Centauri:, Nature, Vol. from CSUF in 1976 and a PhD in Chemistry from 491, pg. 207-211, 2012. Caltech in 1981 followed by a post-doctoral fellowship in Chemical Engineering. Before joining JPL in 1991 she managed the detector and materials research department at Aerojet ElectroSystems.

Amanda Donner is a mission David Sternberg is a guidance and assurance manager at NASA Jet control systems engineer at the NASA Propulsion Laboratory. She was the Jet Propulsion Laboratory, having mission assurance manager for earned his SB, SM, and ScD degrees ASTERIA during development and is in the MIT Department of currently the ASTERIA mission Aeronautics and Astronautics. He is manager for extended mission currently working on the develop- operations. Amanda received her ment, testing, and operation of small M.S. in Mechanical Engineering from satellite attitude determination and control hardware for UC Davis. several small satellites, including serving as a jitter characterization engineer for ASTERIA and the lead ACS Robert Bocchino is a Flight Software operator for the MarCO satellites. Engineer in the Small-Scale Flight Software Group at JPL. He holds a Matthew W. Smith is a member of Ph.D. in computer science from the the Flight System Systems University of Illinois at Urbana- Engineering group at the Jet Champaign, and he was a Postdoctor- Propulsion Laboratory. He served as al Associate at Carnegie Mellon the ASTERIA Project System University. Since joining JPL in 2013, Robert has worked Engineer and Payload Lead during on both technology development and flight projects. He development, and as Mission was the flight software technical lead for the primary Manager during the primary mission. ASTERIA mission. Robert is currently working on His research interests are in systems technology development in the areas of software engineering for space-based optical instruments, development and testing, autonomous flight software, and modeling and simulation, and multi-disciplinary design high-performance space computing. He is leading the optimization. He holds a B.A. in Applied Mathematics FSW development for the ASTERIA autonomy from Harvard University, an M.Phil in Engineering from demonstrations. the University of Cambridge (UK), and M.S. and Ph.D. degrees in Aeronautics and Astronautics from the Brian Kennedy has been a member of Massachusetts Institute of Technology. the Navigation and Mission Design section at NASA's Jet Propulsion Martina Troesch is a member of the Laboratory for the past twenty years. Artificial Intelligence group at the Jet He is currently the Orbit Determina- Propulsion Laboratory. She holds a tion Team Lead for the Dawn Mission B.S. and M.S. from the University of and the Lead for the OSIRIS-REx Southern California in Aerospace Independent Bennu Asteroid Shape Model Team. His past Engineering, as well as an M.S. in work at JPL has included support for the Deep Space 1, Computer Science from Stanford Odyssey, MER, Stardust, Deep Impact, LCROSS and University. EPOXI missions. Brian graduated from The University of Colorado in 1993 with a B.S. in Aerospace Engineering Sciences.

Swati Mohan received her B.S. from Cornell University in Mechanical/Aerospace engineering in 2004. She earned her PhD from MIT Aero/Astro in 2010. Swati’s PhD was in the MIT Space Systems Laboratory on the SPHERES project. She joined JPL in 2010 and has worked various projects since joining such as Cassini, Grail, and OCO-3. Swati is currently the Lead GN&C Systems Engineer on the M2020 mission, specifically working on adding the Terrain Relative Navigation system to the heritage MSL system. She is the Co-Founder and Manager of JPL’s Small Satellite Dynamics Testbed and has been working on Cubesat Attitude Control Systems since 2002.