Deep Space Atomic Clock Mission Overview Todd Ely

Jill Seubert, John Prestage, Robert Tjoelker, Eric Burt, Angela Dorsey, Daphna Enzer, Randy Herrera, Da Kuang, David Murphy, David Robison, Gabrielle Seal, Jeffrey Stuart, Rabi Wang

August 2019

Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement by the United States Government or the Jet Propulsion Laboratory, California Institute of Technology

© 2019 California Institute of Technology. Government sponsorship acknowledged. DSAC Technology Demonstration Mission

DSAC Demonstration Unit Mercury UV Lamp Testing

Multi-pole Trap

Quadrupole Trap

Titanium Vacuum Tube

Develop advanced prototype (‘Demo Unit’) mercury-ion atomic clock for navigation/science in deep space and Earth • Perform year-long demonstration in space beginning August 2019 – advancing to TRL 7 • Focus on maturing the new technology – ion trap and optical systems – other system components (i.e. payload controllers, USO, GPS) size, weight, power (SWaP) dependent on resources/schedule • Identify pathways to ‘spin’ the design of a future operational unit (TRL 7 → 9) to be smaller, more power efficient – facilitated by a detailed report written for the next DSAC manager/engineers

August 2019 jpl.nasa.gov Broad Benefits for Enhanced Exploration & National Security Enable routine use of 1-Way tracking - more flexible/robust mission ops than with 2-Way tracking • Ex.: 3X more radio science data during Europa flybys without constraining other science

Fundamental to enabling real-time, on-board deep space radio navigation • Ex.: 100 meter class trajectory knowledge at entry to Mars atmosphere

Enable use of existing DSN Ka-band downlink tracking capability – improve data accuracy by 10X • Ex.: Determine Mars’ long period gravity and orientation to GRACE-quality using one spacecraft

National security resource to GPS, protected command and control, and other applications • Ex.: Improves upon existing GPS clock performance by 50 times or more

August 2019 jpl.nasa.gov Technology & Operation

Ion Clock Operation Ion Clock Technology Highlights • Short term (1 – 10 sec) stability depends on Local • State selection of 106-107 199Hg+ electric-field contained Oscillator (DSAC selected USO 2e-13 at 1 second) ions (no wall collisions) via optical pumping from 202Hg+ • Longer term stability (> 10 sec) determined by • High Q microwave line allows precise measurement of “atomic resonator” (Ion Trap & Light System) clock transition at 40.5 GHz using DSAC/USO system • Ion shuttling from quadrupole (QP) to multipole (MP) Key Features for Reliable, Long-Life Use in Space trap for best disturbance isolation • No lasers, cryogenics, microwave cavity 3×10!"# MP Test Bed: ���×� < & �. �. ~ 1×10!"$ • Low sensitivity to temperatures, magnetics, voltages � • Radiation tolerant at levels similar to GPS Rb Clocks • QP -Only implementation offers major simplification 5×10!"# QP−Only DU: ���×� < & �. �. < 3×10!"$ � August 2019 jpl.nasa.gov Demo Unit Ground-Based Measured Stability

• DU in MP with Maser input at constant • DU in QP with Maser input at constant temperature temperature • Stability ~1e-15 @ 1-day in MP mode (no • DU/USO configuration tested with similar results drift removed) • Stability < 3e-15 @ 1-day in QP mode (no drift → 87 ps/day or 26 mm/day removed) → 0.26 ns/day or 8 cm/day

August 2019 jpl.nasa.gov DSAC Payload Integrated on the Orbital Test Bed Spacecraft

Ultra-Stable Oscillator (USO) Local Oscillator (FEI)

DSAC Demo Unit (DU) Atomic Resonator (JPL) General Atomics V: 285 x 265 x 228 mm M: 16 kg, Physics Pkg – 6.6 kg Electromagnetic Systems P: 50 W, Physics Pkg – 17 W Group (GA-EMS) Orbital Test Bed (OTB)

GPS Receiver Validation System (JPL-Moog)

Demo Unit designed for prototyping flexibility – pathways to < 10kg and < 30 W possible for operational version

August 2019 jpl.nasa.gov A complex ride story: DSAC is a Hosted Payload on OTB that is itself a Secondary Payload

OTB hosts 6 payloads: GA Orbital Test Bed (OTB)

DSAC Payload (Clock, USO, GPSR)

STP-2 Payload includes 26 spacecraft: • DSX (prime) • COSMIC-2 (prime) • GPIM GA Payloads (2) • Oculus • OTB (DSAC Host) • NPSAT • Prox-1 Commerical Payload (1) • Numerous CubeSats

USAF STP-2 (SpaceX Falcon Heavy) NASA – USAF Quid Pro Quo “Ride for SERB Payloads” USAF ‘SERB’ Payloads (2) August 2019 jpl.nasa.gov Mission Architecture

GPS Sat 1 GA Orbital Test Bed (OTB) • 720 km altitude • 24° inclination GPS Sat 2 Nominal Mission Ops • Collect GPS phase & range data • Collect DSAC telemetry • Validate clock instability < 2 ns @ one-day ( < 0.3 ns goal) GPS Sat n • Validate as a navigation instrument

ViaSat GS CMD & TLM Hawaii GA MOC/SOC Launch June 25, 2019 Colorado USAF STP-2 (SpaceX Falcon Heavy)

sftp DSAC team JPL

August 2019 jpl.nasa.gov Demonstrate DSAC Functionality and Performance in LEO

Housekeeping Telemetry: Metrics to assess DSAC health & status Payload Telemetry: Metrics to assess DSAC state GPS carrier phase & pseudo-range (LC, PC) data & SC ancillary data: Processed to estimate DSAC performance

Payload Commands

SC & Payload Telemetry

LC, PC: measure of range from GPS transmit antenna phase center to OTB receive antenna phase center1 Compute Allan Deviation of the estimated clock time series to assess �� = �⃗! − �⃗" + c ��! − ��" +… clock stability.

Multipath, phase wind- Assess orbit determination up, phase bias, noise... performance with Deep Space Estimated by TDAS Navigation Analog formulation. JPL IGS AC solutions 1Simplified equation for explanatory purposes only

August 2019 jpl.nasa.gov Illustration of the 5-step Clock Analysis

Raw x(t) & y(t)

GPS temp cal and remove gaps

Remove frequency bias

Remove outliers (including day boundary jumps)

Best fit x(t) line removed leaving best detrended x(t) & y(t)

August 2019 jpl.nasa.gov Predicted Clock Determination of CBE DSAC

Mission Reqmt: A.D. < 2.0e-14 @ 1-day

Extracted CBE clock (KM model) A.D. ~ 2.4e-15 @ 1-day

Input CBE clock A.D. ~ 2.1e-15 @ 1-day

1-day

Current predicts indicate DSAC in-space will meet ground based performance (A.D. < 3.e-15 @ 1 day), potential to outperform any existing space clock August 2019 jpl.nasa.gov Deep Space Navigation Analog Experiment Sample and Process Data as if in Orbit Around Mars to Obtain < 10 m (3-s) Orbits

Maximum 3-s Orbit Uncertainty Measurement Type GPS A Plane GPS F Plane 1-Way GPS Doppler 4.9 m 3.8 m Pseudo 2-Way GPS 4.3 m 2.9 m Doppler

August 2019 jpl.nasa.gov DSAC USO & GPS Receiver Are On.

Clock Turn On Scheduled For This Week!

August 2019 jpl.nasa.gov jpl.nasa.gov