The NASA SunRISE (Sun Radio Interferometer Space Experiment) mission recently passed a project review milestone and is now moving into the next phase of mission development. Climate & Space prof. Justin Kasper, the mission’s principal investigator, sums up the mission’s objective:
“SunRISE will detect and study eruptions of radio waves from the Sun that often precede major solar events containing high energy particle radiation. Knowing when and how solar storms produce intense radiation will help us better prepare and protect our astronauts and technology.”
Prof. Kasper is also an investigator on the NASA Parker Solar Probe mission.
We caught up with Asst. Research Scientist Alex Hegedus, who works on the mission alongside Prof. Kasper to hear more about the latest development in the mission timeline.
Congratulations on passing your latest milestone! Can you explain what the milestone was, and where we are in the mission timeline?
We recently went through Key Decision Point C (KDP-C), the dividing line between Phase B and Phase C in the NASA project life cycle. KDP-C is a divider between a mission’s formulation and its implementation, as seen in the figure here. This milestone in particular was big because it means that as long as we keep on schedule, we are likely a go for launch!
What happens in the next phase?
Next we’ll execute the plan we have spent years formulating. That means spacecraft construction, it means requisitioning equipment, and in general spending more money on physical hardware, as opposed to primarily spending money on people planning before. Here at Michigan, we will be setting up a central data server for the SunRISE mission Science Operations Center. This will interface both with NASA Jet Propulsion Laboratory (JPL) servers, as well as Amazon Web Services Elastic Cloud Computing instances to do some of the more computationally intensive steps of the science processing. We will also be finishing up the creation of the processing software itself, with lots of conversations happening between U-M, JPL scientists, and spacecraft engineers to make that happen.
Can you give us some background on the SunRISE mission? What led to its conception, and what does the mission hope to accomplish?
As with the Parker Solar Probe mission (launched 2018), we are really standing on the shoulders of giants here. People have thought of creating a space-based low-frequency synthetic aperture with multiple satellites for decades, but it wasn’t until recently that a few key pieces of the puzzle fell into place.
The first is the increasing prevalence of quality commercial off-the-shelf parts for satellites, and a strong commercial launch market allows us to maintain a low-cost for the mission, a necessity to get the ball rolling on this class of missions. Next is the lower overall cost for the compelling science that could be achieved using SunRISE. In the past, solar radio bursts have been measured by single spacecraft. But an array like SunRISE could help pinpoint the location of these bursts within larger space weather events. This would help answer the open question of how these events accelerate the energized solar particles that can affect people and power systems on Earth.
By creating a large array from smaller, distributed components, SunRISE is a unique solution to the challenge of installing large instruments in the space environment. Has this been done before?
Some measurements by design have required multiple spacecraft. For instance, the NASA Helios missions consisted of two spacecraft that traveled close to the Sun with slightly different orbits. Once there, the spacecraft sent a beam of radiation between them. They then recorded the effects of the plasma of the inner heliosphere on the beam. These measurements led to estimates of the strength of the magnetic field and the electron density between the spacecraft.
SunRISE is unique in that it requires a high degree of synchronicity between the spacecraft, as well as sub-meter precision for the location of each spacecraft at all times. This allows the individual spacecraft to combine their data into an accurate image of the sky.
Do you see this mission as a sort of proof of concept for similar approaches in the future?
Absolutely. There have already been studies done of constellations of up to thirty-two spacecraft, compared with the six on the SunRISE’s mission. I’m involved in proposed concepts for arrays on the lunar surface that range from 128 antenna to 100,000. There are definitely a lot of opportunities for space-based radio in the near future, and the potential wealth of scientific knowledge they could bring.
What are some other potential uses that you see for this approach?
In particular, observing the redshifted 21-cm neutral Hydrogen signal at low frequencies from the lunar far side would enable a look into the deep past of the universe, and would constrain important cosmological parameters, like the fraction of ionized dark matter in the early universe. Missions like FARSIDE and FarView have these goals.
Making high-quality sky maps at lower frequencies would open up a whole new window to the universe. One particular use for these maps would be determining the structure of Double Radio Sources Associated with Active Galactic Nuclei (DRAGNs), which could tell us more about the shock structure and dynamics of jets coming from black holes at the cores of galaxies. This is the primary science target of the RELIC array, another concept array outlined in a paper in Experimental Astronomy which plans to have thirty-two spacecraft.
We can also turn this synthetic eye in the sky back on Earth and try to observe the synchrotron emission from relativistic particles in the planet’s radiation belts. This is predicted to be a relatively weak signal for us compared to Jupiter, whose equivalent emission has been already mapped in detail. It is also predicted to be a low frequency signal only observable from space. Characterizing this emission on a daily basis would lead to a better understanding of the global distribution of energetic electrons in the radiation belts. One could also make detailed maps of Earth’s Auroral Kilometric Radiation, brighter transient emission that marks a local instability in the magnetosphere near the poles.
Can you talk about your respective roles in the SunRISE mission?
I am implementing the processing pipeline that will deliver the key data products of the mission. My title on the mission is Lead Co-Investigator of the Science Data System. Along with U-M Space Physics Research Laboratory (SPRL) Project Manager Cole Heckathorn, I oversee and perform the day-to-day construction of the SunRISE data processing pipeline. I work very closely with scientists and engineers from JPL on this aspect of the mission to make sure there is a common understanding of the expectations for the ins and outs of the Science Data System.
I also lead the student collaboration with the Helio Multidisciplinary Design Program (MDP) group, which is working to create a ground-based radio array and a parallel SunRISE software pipeline.
Tell us about your journey from student to Assistant Research Scientist. How did you become involved in the SunRISE mission?
I first began working with SunRISE in 2016. I spent that summer and the next at JPL working on simulating the performance of SunRISE, along with another space-based concept array called RELIC. There I worked closely with SunRISE Project Scientist Joseph Lazio, who would later serve on my PhD committee in 2019. Later in 2016 came the NASA Stand-Alone Missions of Opportunity Notice (SALMON) call under which SunRISE was submitted. Some of the work I had done that first summer had made it into the proposal. Since that time I have been a central part of the team, speaking at the NASA site visit at the end of Phase A in 2018. Now I’m an Assistant Research Scientist in the Climate & Space department, a full Co-Investigator on the mission, and the lead Co-Investigator of the Science Data System, where all of the scientific analysis of the data happens.
What are your future plans?
I plan to work in this line of research for at least the next few years through the SunRISE mission. Then I hope to apply my expertise and code base written for SunRISE to future space-based arrays.