Mini-spacecraft built by ASU students will study urban heat island effect

Students get hands-on introduction to space workforce by building an operational satellite

August 27, 2019

Editor's note: This story is being highlighted in ASU Now's year in review. Read more top stories from 2019.

Editor's note: The following update was added to this story on Nov. 4, following the successful launch of the Phoenix CubeSat. Members of the Phoenix student engineering team gather in the lab, with team lead Sarah Rogers holding a 3D test model of the Phoenix cubesat. Electronic components on the bench are part of the development hardware. Image credit: Craig Knoblauch/Arizona State University Download Full Image

On Saturday, Nov. 2 at 6:59 a.m. Arizona time, the Arizona State University-led Phoenix CubeSat was launched into space onboard the Antares II rocket from Wallops Flight Facility in Virginia as part of a Cygnus resupply mission to the International Space Station (ISS).

“Watching our Phoenix CubeSat launch meant more to me than I can ever possibly put into words," said Sarah Rogers, project manager for the Phoenix CubeSat and a graduate student in the Fulton Schools of Engineering. “And the fact that I got to share that experience with my team, who all mean so much to me, made the experience all the more special.”

The spacecraft safely arrived at ISS with its cargo on Monday, Nov 4. It will remain at the ISS until mid-January, when it will depart the station and deploy its CubeSats, including Phoenix.

“Then, we’ll get to see Phoenix come out of the Nanoracks deployer, deploy its antenna, and detumble,” said Rogers. “Once Phoenix has been deployed, the operations phase of the project will officially begin, and we will be able to collect data from the spacecraft while it is in orbit.”

During the first month or so, the team will perform checkout operations to monitor the health of the spacecraft and make sure they are comfortable commanding it from orbit before the science investigation officially begins. All operations will be conducted from ASU by the student team.


If all goes as planned, one day this October a spacecraft the size of jumbo loaf of bread will leave from Wallops, Virginia, packed aboard a cargo rocket bound for the International Space Station.

The spacecraft is a cubesat named Phoenix, and it is the creation of more than 100 science and engineering students, faculty and researchers at Arizona State University.

On Aug. 18, the Phoenix spacecraft was hand-delivered by the student team to Nanoracks, a launch integrator, at their facility in Houston. There it underwent final tests and preparations for its launch to the Space Station, planned for Oct. 21, 2019. After it arrives at the Space Station, Phoenix will be sent into low-Earth orbit sometime early next year.

The Phoenix spacecraft is designed for a two-year mission to take thermal images of several American cities (including its namesake, Phoenix) by day and by night.

The students who built Phoenix came from ASU's School of Earth and Space Exploration, the Ira A. Fulton Schools of Engineering, the School of Geographical Sciences & Urban Planning, the Herberger Institute of Design and the Arts and the Walter Cronkite School of Journalism and Mass Communication.

Students have made up by far the largest part of the Phoenix workforce. Ranging from those pursuing graduate degrees to first-year undergraduates, a total of 96 students are either working on or have contributed to the project, which began in April 2016. A number of students who contributed to the mission have already graduated from ASU, with several entering the national aerospace workforce.

"The Phoenix cubesat is a student-run project funded by NASA with an educational mission to train students in satellite development," said Judd Bowman, the mission's principal investigator and professor in the School of Earth and Space Exploration. "We have incorporated a student science team mentored by ASU professors to help provide scientific interpretation of the thermal images that the satellite will acquire from orbit."

As project head, Bowman is joined by Assistant Professor Daniel Jacobs, whose role is faculty mentor for the student workforce.

Said Jacobs, "NASA's goal was space workforce education, but they required a real target for the program — a technology demonstration or a scientifically worthwhile project."

Small satellite, big task

The Phoenix spacecraft is a cubesat, 4 inches square by 12 inches long, a standard size and shape devised to make it easier for anyone to develop a small satellite. Four ultra-high frequency antennas sprout from one end like stiff whiskers, and solar panels wrap around two long sides to provide power. Sun and Earth sensors feed data to a commercial gyroscope unit to keep Phoenix aimed at the ground.

The heart of the spacecraft is its infrared imager, a commercial microbolometer from FLIR Technologies. This provides a resolution of 640x512 pixels. Fitted with a 100mm lens, it has a 5 degree by 6.2 degree field of view that covers an area 22 miles by 27 miles on the ground and provides a resolution up to 228 feet per pixel.

Phoenix will travel in a 92-minute orbit inclined 52 degrees to the equator at an altitude of about 250 miles, matching that of the Space Station. This means it passes over the entire contiguous United States, plus Hawaii, so it will see a given point within the geographic limits at many different times of day. 

The initial plan is to concentrate the imaging on the city of Phoenix, both because it is the mission's hometown and because the ASU ground station provides easy radio communications to the satellite. Images and data will be downloaded at the School of Earth and Space Exploration and studied by the team, and new commands will be uplinked to the spacecraft, all from the Tempe campus. 

An additional reason is that the Phoenix metro area has become one of the fastest growing regions in the United States, which ties directly into the scientific plans for the spacecraft.

Islands of warmth

As urban areas develop, changes occur in the landscape. In the case of metro Phoenix, its land coverage and land usage are both increasing faster than in most other cities. Typically, as land cover and land usage increase, the change from a rural or agricultural landscape to an urban metropolis yields warmer temperatures than in the surrounding areas. This phenomenon is called the urban heat island.

Seen by day or night with heat-sensitive eyes, cities loom as islands of warmth embedded in "seas" of cooler terrain. The Phoenix mission's primary scientific task is to study the heat radiation from the selected cities to determine their urban heat island effects. 

The effect arises from a city's hardscape — its buildings, streets and pavements — which absorb heat from the sun during daytime, then cool off overnight at a slower rate than the natural landscape surrounding the city. Urban heat islands create negative effects on sustainability and the overall quality of life for people living in them.

Said Jacobs, "The goal is to image temperature variations across cities that include parks, residential neighborhoods and streets with a lot of shade trees — as well as unshaded industrial areas."

During its two-year mission, Phoenix will track changes in urban temperature patterns due to daily and seasonal effects.

In preparation for the mission, the students have charted how land is used in different parts of Phoenix and several other cities to identify local climate zones. These range from open grassland to compact, high rise urban areas. Students will use zone identifications to interpret their measurements from orbit and to investigate how the different uses of land within a city affect its heat island.

Learning experiences

For many of the students, the Phoenix project stretched their ideas of what they could do. Starting with off-the-shelf hardware components (including electronics), linking them together within the tight confines available, and writing software to control them so as to gain scientifically usable data — the whole process was a challenging learning experience.

Students were accountable for meeting milestones and schedules, along with technical requirements determined by NASA and the launch provider. As Bowman said, "There aren’t many shortcuts you can take when you’re building a spacecraft."

Sarah Rogers joined the project as an undergraduate student and is now pursuing a master's degree in aerospace engineering in the Fulton Schools. She has been Phoenix project manager since the start.

"This was the first opportunity that students had to program and integrate complex spaceflight hardware," she said. "It required them to spend a lot of time with the hardware to get it all working properly."

The hardware came from different vendors and didn’t all work seamlessly together, she explained. The students on the team spent a lot of time and effort in really getting to know the hardware inside and out to ensure everything would work as a unified system.

Rogers said, "Programming our hardware was very different from using an Arduino microcontroller board, for example. With those, everything is open source, it's easy to use, and there's a wide community to call on for advice." (Arduino boards are popular with electronics hobbyists looking to build digital devices.)

As a result, she says, the team made mistakes, such as circuit boards getting fried by too-high voltages. "We had to learn how to handle the hardware safely, at the same time we were struggling to get everything to work together."

In the end however, Rogers said, "This experience led the student team to develop a professional lab environment that operated on standard space industry practices."

Not taught in classrooms

Yegor Zenkov, an undergraduate student in materials science in the Fulton Schools of Engineering, found that tasks which might look simple turned out difficult: "The biggest challenge for the payload team was trying to get raw, uncorrected data from the camera and calibrate it for space."

The student team was starting from scratch, he said. "At the beginning, none of the team had any experience with thermal cameras or microbolometers."

Every time they learned something new about the camera, they had to rewrite their test plans. And every test run involved several days of around-the-clock monitoring. The first set of tests in a vacuum chamber took months to set up — and then had to be redone.

Zenkov said, "This project forced me to learn and do research quickly, constantly stay nimble under pressure, and understand how to manage a team of volunteers."

Devon Bautista, now a graduate student in computer engineering at the Fulton Schools, started on the Phoenix project as an undergraduate. Involved in developing the flight software, he found that in working with multiple developers, communication is important and that it is sometimes difficult to reach a consensus on ideas.

"I learned how to translate technical concepts abstractly so other teams could understand them," he said. "In addition, this was my first large collaborative software project. Working with many developers from different backgrounds, I discovered which practices were good and effective, as well as which ones weren't."

Looking toward a career in systems engineering, Rogers found the project all-engaging. "My role in Phoenix has given me the opportunity to work on the science side as well as practically every technical area of the spacecraft."

She added, "I also gained valuable skills in interdisciplinary communication because Phoenix was created by individuals from different engineering and science backgrounds who didn't all use the same vocabulary."

Ultimately, Rogers said, "The skills I learned from Phoenix taught me both technical and personal lessons I could never get from a classroom setting."

For Bowman, the project is a new way for ASU to help the local community. "We see the Phoenix project as contributing to the trend of helping local governments and communities gain direct access to space to address their own needs."

Phoenix will be the first student cubesat launched by ASU, which prompts Bowman to say, "As the students reflect on how far we’ve come together — from knowing very little about satellite development to delivering an operational spacecraft — I think they should be quite proud of what they've achieved."

Animated GIF: The flight-ready Phoenix cubesat in a stop-action animation by team member Vivek Chacko.

Robert Burnham

Science writer, School of Earth and Space Exploration


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ASU water policy expert addresses new drought plan for state

August 27, 2019

State will take less water from the Colorado River under a new contingency plan

The Southwest’s long-standing drought has left the state staring down a historic and first-ever Colorado River water cutback in 2020. 

Starting Jan. 1, Arizona will see a 6.9% reduction of Colorado River water under the Lower Basin Drought Contingency Plan, which was finalized in May with California, Nevada and the federal government. Mexico will give up 3% of its allotment under a separate agreement.

The cuts are part of a plan to keep Lake Mead, a reservoir at the Arizona-Nevada boundary, functional. Water levels for both Lake Mead and Lake Powell have precipitously dropped as a result of historic over-allocation and a drought that started in 2000. 

ASU Now spoke to Sarah Porter, director of the Kyl Center for Water Policy at ASU’s Morrison Institute for Public Policy, about the cutbacks and what they will mean for Arizona’s agriculture and the state’s roughly 7 million residents.

Woman in front of microphone

Sarah Porter, director of the Kyl Center for Water Policy at ASU's Morrison Institute for Public Policy.

Question: Are these cuts a move that has been anticipated for some time, and should Arizona residents be worried?

Answer: Yes, the cuts have been anticipated and were agreed to by the parties to the Drought Contingency Plan or DCP. In fact, until a few months ago, we expected deeper cuts, but good mountain snowpack last winter and aggressive conservation efforts shored Lake Mead up a bit. The cuts are part of a larger plan to safeguard the Colorado River system. The plan was negotiated for several years and finalized this spring.

The Lower Basin DCP incentivizes conserving water in Lake Mead while also imposing bigger and bigger cuts should lake levels fall to certain levels. Water users on the Central Arizona Project, which brings Colorado River water to central and southern Arizona, are in line to take largest cuts because they are the lowest priority users.

The 2020 cuts won’t really be felt by Arizona water users because the state has never built out demand for all of its Colorado River supplies. For years, Arizona water managers have used “extra” Colorado River water for aquifer recharge and other purposes. Annually starting in 2015, Arizona has voluntarily conserved in Lake Mead the equivalent amount of this year’s cut.

Rather than worry, Arizona residents should continue to find ways to permanently use water more efficiently. Statewide, Arizona uses the same amount of water today as it did in the mid-1950s, though we now have seven or eight times the population and a much larger economy. There are still lots of opportunities to stretch our water supplies through conservation and efficiency measures.

Q: Who will be the first group of people to feel the sting of cuts in Colorado River supplies?

A: If Lake Mead falls below 1,075-feet elevation, Arizona will take additional cuts and farmers in Pinal County will be the first to feel the impacts. They plan to turn to groundwater (that is, water pumped from wells) to make up for some of those cuts.

Cities are in a different situation. Municipal providers that use CAP supplies tend to have high priority rights, so they would be among the last CAP users to experience cuts. Many cities in the Phoenix and Tucson areas have diverse water portfolios, including groundwater, reclaimed water and other surface water, which gives them a measure of resilience against cuts in Colorado River supplies. And since passage of the 1980 Groundwater Management Act, growth has been tied to long-term water supplies in the state’s most populous areas, so water providers must plan well in advance for foreseeable supply reductions.

Q: So if agricultural is the first to take a hit, will this mean the cost of fruits and vegetables will likely go up — and by how much?

A: That’s a question for an economist, but I will note that Arizona’s agriculture industry is not monolithic when it comes to water supplies. Right now, only Pinal County farmers are facing cuts — other Arizona farmers have higher priority Colorado River rights or get their water from other sources. Two-thirds of Pinal County’s agricultural revenues come from cattle and dairy. That production will not be directly affected by cuts in CAP deliveries. The county’s main irrigated crops are cotton and hay. 

Q: What’s the effect going to be on individual households and what should consumers be mindful of, or start practicing?

A: For some households, water rates may increase as their water providers take additional steps to ensure water deliveries in the event of decreased Colorado River supplies. In addition, some households in newer developments in Maricopa, Pinal and Pima Counties depend on groundwater and are required to pay into a fund to purchase water supplies to replenish the groundwater withdrawn for their use. This amount shows up as an assessment on county property-tax bills. As fewer supplies become available, the costs of water to meet the replenishment obligation may also increase.

We should always treat water as the precious resource it is here in Arizona. The single best way for an individual household to help is to permanently reduce the amount of water used for outside landscaping. 

Q: Is this going to be the new normal or a sign of things to come?

A: We should think of this as the new normal. Lake Mead is over-allocated. The prolonged drought has exacerbated the problem because it results in less extra water in the system. There are signs that the region is aridifying, meaning that average flows in the Colorado River may decrease.

We shouldn’t overlook the conservation efforts that are critical to keeping the Colorado River system functional. The Drought Contingency Plan includes important ground rules for conserving water in Lake Mead, and Arizona’s Colorado River Indian Tribes and the Gila River Indian Community, along with CAP, will be conserving and storing significant quantities of water in the lake.

Top photo: The Lake Mead reservoir near the Nevada/Arizona boundary. Photo by Charlie Leight/ASU Now

Reporter , ASU News