LightSail 1 Mission Results and Public Outreach Strategies By Bruce BETTS1), Bill NYE1), Jennifer VAUGHN1), Erin GREESON1), Richard CHUTE1), David A. SPENCER2), Rex W. RIDENOURE3), Riki MUNAKATA3), Stephanie D. WONG3), Alex DIAZ3), Douglas A. STETSON4), Justin D. FOLEY5), John M. BELLARDO5), and Barbara A. PLANTE6) 1)The Planetary Society, Pasadena, California, USA 2)School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana, USA 3)Ecliptic Enterprises Corporation, Pasadena, California, USA 4)Space Science and Exploration Consulting Group, Pasadena, California, USA 5)California Polytechnic State University, San Luis Obispo, California, USA 6)Boreal Space, Hayward, California, USA Conceived by The Planetary Society, and funded by private donations, the LightSail program consists of two missions, LightSail 1 and LightSail 2, seeking to demonstrate controlled solar sailing using a 3U CubeSat spacecraft bus. This paper reports results of the LightSail 1 mission, a five-week 2015 mission in low Earth-orbit that successfully demonstrated the solar sail deployment approach. Once in orbit, the LightSail 1 mission operations team stepped through a two-week checkout period, with useful images and spacecraft performance data transmitted to two ground stations in the United States. Following resolution of several significant anomalies during the early phases of the mission, the LightSail 1 solar sail was successfully deployed. Following sail deployment, spacecraft subsystem testing was completed and an image showing the deployed sail was downlinked before the spacecraft re-entered the atmosphere. Through the LightSail program, The Planetary Society also seeks to engage and excite the public. LightSail 1’s public outreach strategy included: (1) Inspiring spokespeople, including The Planetary Society Chief Executive Officer Bill Nye, as well as board member Neil deGrasse Tyson; (2) Good choice of publicity timing; (3) Science education, including transparent regular coverage of the mission development and operations; (4) Historical storytelling - footage of co-founder Carl Sagan discussing solar sailing with Johnny Carson on a 1976 episode of “The Tonight Show” paired with LightSail described by present leader, Bill Nye; (5) Public engagement campaigns - these included Selfies to Space, where the public was able to submit photos and/or names to ride on board LightSail 2; (6) a Kickstarter campaign that expanded the citizen-funded aspect of the mission attracting 23,500 backers who gave $1.3M USD; (7) Multimedia –web microsite, videos, animations, Planetary Radio, social media, and print materials; and (8) Special events – both physical at launch, and virtual. Key Words: Solar Sailing, CubeSat, Outreach 1. Introduction spacecraft in November 2010. Following a delayed deployment from FASTSAT, NanoSail-D2 deployed a 10 m2 In 2009, The Planetary Society initiated the LightSail solar sail from a 3U CubeSat.3) The LightSail program was program to advance the maturity of solar sailing technology structured to build on these successes, demonstrating a using the 3U CubeSat platform.1) The LightSail 1 mission was controllable solar sail for the in-space propulsion of CubeSat designed to provide on-orbit validation of the CubeSat platforms. functionality and demonstrate sail deployment in low-Earth Founded in 1980, The Planetary Society is the world’s largest orbit, while the subsequent LightSail 2 mission would and most influential public space organization group, with more demonstrate sail control in order to raise orbit apogee. than 40,000 active members. With a charter to “inspire and LightSail 1 was competitively awarded a launch slot as a involve the world's public in space exploration through secondary payload through NASA’s Educational Launch of advocacy, projects, and education,”4) The Planetary Society Nanosatellites (ELaNa) program. Following a five-year crafted a public outreach campaign centered on the LightSail development, LightSail 1 launched as part of the ULTRASat program (Fig. 1). payload on an Atlas V launch vehicle on May 20, 2015. In this paper, the LightSail 1 mission results are presented. LightSail 1 was the third solar sailing mission to successfully A summary of the LightSail spacecraft design is provided in launch, achieve sail deployment, and operate in space. In May Section 2, and the on-orbit performance of the LightSail 1 2010, the Japanese space agency JAXA launched a mission to spacecraft is evaluated in Section 3. Anomalies encountered Venus with a secondary payload called Interplanetary Kite- during the mission are described, along with the flight team’s craft Accelerated by Radiation Of the Sun (IKAROS). Three anomaly response actions. In Section 4, the LightSail public weeks after launch, IKAROS was successfully deployed and outreach campaign is described. The planned LightSail 2 became the first-ever solar sailing demonstrator.2) Subsequently, mission is described in a separate paper.5) NASA launched the NanoSail-D2 on board the FASTSAT 1 2. LightSail Spacecraft Design and manages deployments as directed by the avionics board. Four independent triangular aluminized Mylar® sail sections The LightSail spacecraft design adopted the 3U CubeSat 4.6 microns thick are Z-folded and stowed in the four sail bays standard in order to leverage a growing vendor supply chain of at the spacecraft midsection. Fig. 2 shows LightSail 1 in a off-the-shelf spacecraft components, and assemblies that partially deployed state, with two solar panels fully deployed, facilitate flight system integration. In the LightSail CubeSat two partly deployed and two bays with folded sail underneath. design, a 1U volume is reserved for the avionics section, which Each sail section is attached to a 4-m Triangular Retractable has hinges for four full-length deployable solar panels. The And Collapsible (TRAC) boom made of elgiloy, a non- solar sail assembly occupies 2U, partitioned into the sail storage magnetic non-corrosive alloy; these booms are wound around a section and the sail motor/boom drive assembly. LightSail is common spindle driven by a Faulhaber motor containing Hall designed for deployment from a Poly-Picosatellite Orbital sensors. The sail system is deployed when FSW initializes the Deployer (P-POD). Four side-mounted solar panels are motor and then commands a prescribed number of motor counts deployable, and a deployable monopole antenna is used for RF to extend the sail sections to their desired positions. Fully communications. deployed, the square sail is about 8 m on the diagonal, with a The avionics section houses two processor boards, a radio, total sail area of 32 m2. batteries, sensors and actuators, and associated harnessing. LightSail 1 was designed to utilize torque rods for attitude control, although a flight software error precluded on-orbit actuation of torque rods. Two small solar panels (one fixed at each end of the CubeSat) and four full-length deployable panels provide power and define the spacecraft exterior. The larger solar panels are in their stowed configuration until either autonomously commanded by onboard software or manually commanded from the ground. With solar cells populating both sides of each large panel, they generate power whether in the stowed or deployed configuration. However, the panels must be deployed before solar sail deployment. Deployment of all four deployable solar panels is accomplished with a common burn-wire assembly mounted near the RF antenna assembly. Each solar panel carries Sun sensors, magnetometers, power sensors and temperature sensors. Two opposing large solar panels are equipped with cameras for imaging sail deployment. Fig. 2. LightSail 1 engineer Alex Diaz showing the folded solar sail segments in the payload bays. 3. LightSail 1 Mission Operations The Atlas 5 launch carrying the X-37B spaceplane and the ULTRASat payload including LightSail 1 occurred on May 20, 2015. The launch vehicle targeted orbit altitudes of 356 km x 705 km, with an orbital inclination of 55°.6) The last of the eight ULTRASat P-PODs to be actuated, LightSail 1 was deployed into orbit two hours after launch. Fig. 1. The Planetary Society Chief Executive Officer Bill Nye with a full-scale engineering-model of the LightSail 3U CubeSat. The spacecraft is controlled by flight software (FSW) that allocates functionality to two different processor boards. The main avionics board is tasked with spacecraft commanding, data collection, telemetry downlink, power management and initiating deployments. The payload interface board (PIB) integrates sensor data for attitude control, commands actuators 2 Fig. 3. LightSail 1 was integrated with the flight P-POD (left), which was configured as part of the ULTRASat payload (right). Fig. 4. Cal Poly ground station antennas tracking LightSail 1. LightSail 1 was controlled from ground stations located at validated via a command to turn off rate gyros. California Polytechnic University, San Luis Obispo (Cal Two days after launch, it was noticed that a file in the Poly) and Georgia Institute of Technology (Georgia Tech). onboard file system was rapidly growing in size. There was The stations were networked to a telemetry database server at concern that the Linux system could crash due to a file size Cal Poly, and commanded by operators at terminals at Cal overload. Just before the next planned tracking station Poly and Georgia Tech. The Cal Poly station utilized a dual- overflight, before the flight team could take action, the board phased Yagi antenna