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a16z Podcast | New Year, New Horizons -- Pluto!
36 segments available
What (on earth) does it take to get a signal to Pluto? Stanford senior scientist and astronomer Ivan Linscott, part of the team that ran the radio science experiment on the New Horizons probe, shares in conversation with a16z's Frank Chen all the nitty gritty details about their project using Ruse radio transmissions to gather info about Pluto. Listen in on exactly what it really takes to do so -- everything from commandeering old Cold War spy technology and plutonium to completing the entire mission on approximately 250 watts, and including other such highlights as a motorcycle riding, guitar playing, leather jacketed, tattooed FPGA fixer coming to fix everything when it seemed a lost cause, and the satellite going dark just moments before contact. From deep tech details to the drama of accomplishing such a difficult mission, this podcast is all about how, exactly, we sent a radio signal to Pluto.
Segments Timeline
Sending Signals to Pluto
In this segment, Frank Chen introduces Stanford senior scientist Ivan Linscott, who discusses the intricate details of sending signals to Pluto. Linscott is part of the team behind the radio science experiment on the New Horizons probe, focusing on digital signal processing and observational radio astronomy.
"hi everyone welcome to the a 6nz podcast today's episode hosted by Frank Chen is a conversation with Stanford senior scientist and astronomer Ivan Linscott and it is all about the juicy nitty gritty m..."
The Journey to Pluto
Frank shares his personal experience of being captivated by the New Horizons mission in 2015 while dealing with Wi-Fi issues at home. He recounts how he connected with Ivan Linscott through a mutual acquaintance, leading to a fascinating discussion about the design process and mission details.
"exactly you send a signal to Pluto Ivan Linscott is part of the team that helped the radio science experiment or Rex experiment that went up with the new Horizons probe and will use radio transmission..."
From SETI to NASA
Ivan Linscott explains his journey to Stanford, driven by his interest in the SETI project and high-performance spectroscopy. He details his work on radio systems for pulsar detection and how this led to his involvement with NASA and the development of communication systems for space missions.
"telling me stories about the design process and the mission and it was just so fascinating that I was convinced that you would be excited to hear Ivan's stories and so here we are and maybe you can te..."
Radio Occultation Explained
Linscott dives into the concept of radio occultation, describing how radio signals can be used to extract atmospheric properties of celestial bodies. He discusses the initial plans for the Pluto mission and the challenges of modifying existing technology to capture signals from Pluto.
"with the space sciences group and electrical engineering under professor Tyler there and it was his interest to do radio science experiments in the outer planets which attracted me very much one of th..."
Innovations for New Horizons
This segment covers the innovative technology developed for the New Horizons mission, including the radio science experiment called REX. Linscott highlights the mission's objectives, such as measuring Pluto's atmosphere and surface characteristics using radio signals.
"of proposals and so we teamed with us with a group of Southwest research led by Allen Stern to do this new Pluto mission they could call new horizons we became the radio science experiment called recs..."
Powering the Mission
Linscott explains how the New Horizons probe is powered by a radioisotope thermoelectric generator (RTG) using plutonium. He discusses the challenges of operating on a modest power budget of 250 watts and the implications for running scientific instruments during the mission.
"that true well the pioneers are out there further yeah this is the farthest radius of occultation experiments has ever been done and the furthest by static radar for this radar experiment that's been ..."
The Plutonium Challenge
In this segment, Linscott addresses the complexities of using plutonium as a power source for the mission. He recounts the challenges faced when a leak was discovered at the plutonium processing facility, which threatened the timeline and feasibility of the mission.
"turn out you can't run them all at the same time oh and my steering or am i doing science so you got you can do four out of five instruments and so one of them has to has to be turned off but fortunat..."
Navigating Regulatory Hurdles
Linscott discusses the regulatory challenges involved in acquiring plutonium for the New Horizons mission. He explains the extensive approvals required from various government bodies and the public concerns regarding the safety of launching a plutonium-powered spacecraft.
"so there was a lot of pressure on the mission to design build and launch yeah so you have to build this thing that's never been built before you're racing against time because otherwise the atmosphere..."
Racing Against Time for Licensing
The segment details the intense timeline for obtaining the necessary licenses for plutonium use in the New Horizons mission. Linscott contrasts the lengthy licensing process for previous missions with the urgent six-month deadline they faced, illustrating the pressure and challenges of space mission planning.
"wasn't the entire piece but it was about enough so that was brought over to the processing facility that could package it which was not shut down and they did that they packaged it put it up tested it..."
Glenn's Leadership in Crisis
Linscott highlights Glenn Fountain's pivotal role as program manager during a critical phase of the mission. He describes how Glenn's problem-solving skills and statesmanship helped navigate funding issues and bureaucratic hurdles, ultimately ensuring the mission's progress despite numerous challenges.
"it was amazing I just didn't think our odds were we're very good for that to happen nobody really did but then tell us some more about Clinton so what was his role on this mission well Glenn became ou..."
Compromises in Power Supply
This segment covers the challenges faced with the power supply for the New Horizons spacecraft. Linscott explains how the team had to adapt to using older plutonium sources, which resulted in a lower power budget than initially planned, affecting the mission's communication systems.
"that's fantastic and so you get part of the plutonium that you need and who was the supplier of the last part that was Department energy okay good so now we've got enough plutonium actually we were st..."
Innovating Under Constraints
Linscott discusses the technological innovations required to adapt to the reduced power budget for signal acquisition. He explains the use of radiation-hardened FPGA technology and the challenges of ensuring reliable communication with the spacecraft, emphasizing the ingenuity required to overcome these obstacles.
"tired plutonium from a variety of sources and now you have a much lower power budget right we were initially offered a chance to implement our new technology for acquisition of the signal from that wa..."
The One FPGA Challenge
In this segment, Linscott describes the critical decision to implement a single FPGA for the mission instead of two. He explains the implications of this choice on design and reliability, highlighting the risks and the need for a robust solution to ensure successful communication with Pluto.
"you've got a problem the Minority Report yes sir that's right but it will turn out that it will be the case that you'll get three or two well essentially all the time so those are limited in capacity ..."
Kamakshi's Breakthrough in Signal Processing
Linscott shares the story of Kamakshi, a student who tackled the challenge of signal processing for the New Horizons mission. He details her innovative approach to filtering signals and the historical context of her techniques, showcasing the blend of creativity and technical skill required for space exploration.
"and that was good from a lot of reasons because the one of the design guidelines from the mission is that you have to have a margin of gates in these FPGA that is high enough to give you assurance tha..."
Overcoming Technical Setbacks
This segment recounts the struggles faced by Linscott's team in getting their FPGA design to work. He describes the year-long effort to troubleshoot and resolve fundamental issues, illustrating the persistence and dedication required in the face of technical challenges in space missions.
"linear Lisa called fi RS finite impulse response filters but a 10,000 element F IR is unimplemented all there is no algorithmic stability that could you could possibly find in an any computing technol..."
The SWAT Team Intervention
Linscott narrates the intervention of a 'SWAT team' sent to assist with the project when concerns arose about its viability. He highlights the collaborative spirit that emerged from this situation, leading to the introduction of experienced FPGA programmers to help resolve the issues faced by the team.
"better part of a year not getting it to work wow that long yeah yeah and after and that it wasn't a whole design it was just a small test piece that uses maybe a tenth of the hundred thousand gates it..."
Mark's Magic Touch
The arrival of Mark, an FPGA programmer with a unique coding discipline, proved pivotal. His strict approach to coding helped identify and rectify the issues that had plagued the project, leading to the successful operation of the first test module and subsequent modules for the New Horizons mission.
"prickly about this right the guy who is head of that evaluation was a former Stanford graduate student of not too long ago who was now the payload chief engineer and Mark worked happily and we became ..."
Barely Making It Work
After overcoming initial hurdles, the team managed to get the FPGA to work, but with very little margin for error. Ivan explains the delicate balance they had to maintain to ensure the system functioned correctly, demonstrating the high stakes involved in the mission to Pluto.
"always helps the other was that mark says you know I have a very strict discipline about how I code there are certain choices you can make in the language of the code that are absolutely guaranteed to..."
Final Adjustments Before Launch
As the project neared completion, additional functions were requested for the FPGA. Ivan recounts how the team managed to fit these last-minute changes into the already tight constraints, showcasing the ingenuity and adaptability required in space missions.
"FB 25 Kate's not 25 percent no 25 said less than 1% so we went to the project and said okay here's the deal it works it works it barely fits it it works it fits we can we've demonstrated it across the..."
Communicating with Pluto
Ivan explains the communication process with the New Horizons spacecraft, detailing how signals were transmitted from Earth using deep-space stations. He describes the technical specifications and the challenges of maintaining a connection with a probe billions of miles away.
"under Yukon you know non-use gates yeah lord knows how that actually the routing worked but again that was Mark's magic be able to kind of groom the routing you do these look you do these and that's f..."
The Doppler Effect Explained
In this segment, Ivan delves into the Doppler effect and how it impacted the signals received from Pluto. He explains the science behind the frequency shifts caused by Pluto's atmosphere during the spacecraft's occultation, emphasizing the complexity of data collection from such a distant object.
"so during the occultation portion of the fly-through of the encounter we had four of those transmissions going simultaneously actually five and i'll tell you though about the fifth it's the by static ..."
Sampling the Signal
The intricacies of sampling the signal from Pluto are discussed, including the technology used to achieve a high signal-to-noise ratio. Ivan highlights the challenges of capturing clear data amidst the vast distances and environmental noise, showcasing the advanced technology employed in the mission.
"3.7 billion miles out and a system that captures this those waveforms are sampled with noise that's one thousandth of the amplitude of that signal so it's like you see a sine wave thoughtyou sampling ..."
The Ultra-Stable Oscillator
Ivan shares the story of the ultra-stable oscillator (USO) used in the New Horizons mission, tracing its origins back to Cold War surveillance technology. He explains its critical role in ensuring precise measurements and the challenges faced in sourcing this rare technology for the mission.
"signals that were a million to one above the noise power it's Bluto yeah Pluto so what you can do with that is a lot the way we sample it is we have a clock that's running the sampler and on the broad..."
From Cold War to Space Exploration
This segment explores the transition of Cold War technology to modern space exploration. Ivan discusses how the USO was repurposed for the New Horizons mission, emphasizing the innovative use of historical technology in achieving groundbreaking scientific goals.
"its own story because us owes were commonly implemented by the Department of Defense during the Cold War they were used for surveillance if he ever read blind man's bluff about submarine espionage it ..."
Testing and Preparing for Launch
As the New Horizons mission approached launch, Ivan describes the rigorous testing and performance evaluations conducted on the spacecraft. He details the annual checkouts and the importance of ensuring all systems were operational before embarking on the long journey to Pluto.
"were talking about you know four years unbelievable by putting a box over the cable over the Kate didn't they didn't puncture it right they didn't there wasn't an invasive to monitoring because it wou..."
The Moment of Crisis: Losing Contact
In a dramatic recounting, Linscott shares the tense moment when communication with the New Horizons spacecraft was lost just before its encounter with Pluto. He details the emergency conference call and the team's efforts to diagnose the issue, highlighting the high stakes and pressure involved in deep space missions.
"rehearsals we ran the whole process of occultation and radio metric measurement in rehearsal yeah and then somewhere along the way am i right that you lost communication with the satellite at the very..."
Rebooting the Spacecraft: A Race Against Time
This segment covers the team's quick response to reboot the New Horizons spacecraft after it encountered a fault. Linscott explains the technical challenges they faced and how they managed to restore functionality just in time for the critical encounter with Pluto, showcasing the resilience and expertise of the mission operations team.
"spacecraft tucked its head under its wings uh-huh and and shut everything off and tried to find out where Earth was and and turned on a tone that said one of several things happened and you get someth..."
The Unexpected Causes of Failure
Linscott delves into the unexpected reasons behind the spacecraft's fault, including a race condition caused by the complexity of image processing. He reflects on the lessons learned from this incident and the importance of thorough testing in spacecraft missions, emphasizing that unforeseen issues can arise even with extensive preparation.
"it was then it wouldn't take too long to figure out what it was I was in X iteration of the communication so in the next ten hours later what we knew was that the computer had been taking an image tha..."
The Importance of Timely Operations
In this segment, Linscott highlights the critical nature of timely operations during the New Horizons mission. He describes how the operations team successfully restarted the timeline for the encounter sequence, ensuring that the spacecraft captured vital scientific data from Pluto, underscoring the high stakes of space exploration.
"the course of spacecraft missions you come to understand that things always go wrong it's not for the faint of heart that is amazing and so you managed to reboot the computer computer was yeah restart..."
The Legacy of New Horizons Images
Linscott encourages listeners to appreciate the stunning images captured by New Horizons, reflecting on how close the mission came to losing the opportunity for these historic photographs. He emphasizes the significance of the mission's success and the scientific insights gained from the data collected during the encounter.
"completely yeah unbelievable well not completely because what it would have done is we do sacrifice some of the early scientific measurements for the later ones all right for those of you in the liste..."
The Big Dish: A Scientific Landmark
Linscott discusses the Stanford dish, a landmark that also serves scientific purposes. He explains its historical significance in communication technology and its role in NASA's investigations of solar wind properties. This segment highlights the intersection of engineering, science, and exploration in the context of the dish's legacy.
"partnered with the team men at Stanford electrical engineering in the 1960s when it was proposed as a facility to support initially investigative technique that US Navy and Department of Defense was i..."
Tracking Satellites: The Evolution of Technology
In this final segment, Linscott elaborates on the technological advancements that enabled the tracking of satellites using the Stanford dish. He describes the challenges faced in the 1960s and how innovations in electric motors and antenna technology have evolved to support modern space missions, showcasing the ongoing journey of scientific discovery.
"wonderful job with it that's fantastic and then after that period did they shut it down yeah by the late 1970's and early 1980s that work was largely complete that task actually had been taken up to s..."
The Risks of Hydraulic Systems
In this segment, Linscott elaborates on the dangers associated with hydraulic systems used in satellite tracking, particularly the risks posed by high-pressure hydraulic lines. He reflects on the historical context of using such technology and the eventual decision to phase out these systems due to safety concerns and the retirement of skilled technicians.
"motors so but they found out that you could with with something else otherwise they wouldn't built it there's something else is hydraulic motors uh hydraulic motors are very good at having a very high..."
Reviving the Dish: A New Era
Linscott recounts his efforts in the 1980s and 90s to revive the old satellite dish, collaborating with engineer Mike Cousins. They identified the need for improved control systems and receivers, leading to significant upgrades that allowed the dish to operate effectively in a high-interference environment.
"yeah it was a very dangerous job to have which was which was the anti-aircraft control guy who was sat in that seat moving that thing around because if something went wrong you probably weren't going ..."
Finding Signals from Space
This segment highlights the challenges of detecting faint signals from distant spacecraft. Linscott explains how advancements in technology, including electric stepper motors, enabled the dish to track and communicate with spacecraft that had gone silent, showcasing the ingenuity required to maintain contact with these missions.
"and so what we found was that there were a couple of things that were in need clearly one was the control and the other was the receivers the era when the dish was used those receivers could be a rela..."
Sharing the Journey
In the closing remarks, Linscott expresses gratitude for the opportunity to share his experiences in space communication. He reflects on the importance of storytelling in science and the excitement of discussing the intricate details of satellite missions with a broader audience.
"unfortunately I think except from one he couldn't fix it but was there yeah that's fantastic well professor Linscott thanks so much for coming to share these stories their amazing stories and I'm glad..."