WASHINGTON — The upcoming launch of a NASA Earth science instrument on a commercial communications satellite illustrates the promise of, but also the problems with, hosted payloads.

A SpaceX Falcon 9 is scheduled to lift off at 12:30 a.m. Eastern April 7 from Cape Canaveral, Florida, placing the Intelsat 40e satellite into a geostationary transfer orbit. There is a 90% chance of acceptable weather for the launch, the 23rd of the year by SpaceX.

Intelsat 40e, built by Maxar, carries a NASA hosted payload called Tropospheric Emissions Monitoring of Pollution (TEMPO). The instrument, produced by Ball Aerospace, is designed to measure concentrations of atmospheric pollutants such as nitrogen dioxide, ozone and formaldehyde across the continental United States as well as portions of Canada, Mexico and the Caribbean.

“TEMPO, from GEO, will for the first time provide hourly data on air pollution,” said Xiong Liu, TEMPO deputy principal investigator at the Center for Astrophysics | Harvard & Smithsonian, during a call with reporters April 5. Spacecraft in low Earth orbit can provide measurements only once per day for a given area as they pass overhead, usually at the same time each day.

TEMPO will also provide that data at a much higher resolution: “down to the neighborhood scale,” said Karen St. Germain, NASA Earth science division director.

Those involved with the project emphasized the benefits of flying TEMPO as a hosted payload rather than as a standalone satellite. “The TEMPO program really is a win-win-win for the major entitles involved,” said Aaron Abell, TEMPO project manager at Maxar. “It allows unused capacity on Maxar’s heritage satellite design be leveraged for government missions. This reduces the cost of access to space for the government as well as reduces the cost for Intelsat as they’re compensated for their support of the TEMPO mission.”

When NASA selected TEMPO for development in 2012, there was widespread enthusiasm in both government and industry about hosted payloads. A steady stream of commercial GEO satellites, at the time averaging 20 to 25 per year, appeared to offer plentiful rides for communications, Earth observation and other payloads.

However, few such payloads have flown. The U.S. Air Force allowed a contract vehicle for flying hosted payloads, called HoPS, to expire in 2019 because of a lack of military payloads seeking rides. At the same time, a sharp downturn in the GEO communications satellite market reduced the supply of satellites that might accommodate payloads.

That latter issue affected a NASA project called GeoCarb, which the agency originally selected to fly as a hosted payload on a GEO satellite through SES Government Solutions. However, in February 2022, NASA announced it would instead look to fly GeoCarb on its own satellite after concluding there were no available satellites that could host the payload for launch by the end of 2024. In November, NASA announced it would cancel GeoCarb because of cost overruns.

“There have not been as many as originally predicted,” acknowledged Kevin Daugherty, TEMPO project manager at NASA’s Langley Research Center, of hosted payloads. “However, some of the things that we’ve learned from TEMPO is how to work with our commercial partners and commercial practices.”

One issue he and others involved in the project mentioned was lining up schedules for payload development with those for the host satellites. “One of main reasons why some of those hosted payload opportunities don’t mature is schedule risk,” said Jean-Luc Froeliger, senior vice president of space systems at Intelsat. “For a commercial operator, schedule is extremely important. A satellite has to be built quickly. It has to be launched and in service as fast as possible.”

Abell cited a “myriad of details” for finding a host that include schedule as well as finding a satellite technically able to accommodate a payload and located in the right part of geostationary orbit. “It’s multiple factors that made TEMPO work,” he said, “but also complicate the process.”

TEMPO was able to mitigate the schedule risks associated with hosted payloads because the instrument was already built by the time that NASA selected Maxar to host it in 2019. “It has helped us fit into the commercial timeline for spacecraft development that moves at a very rapid rate,” Daugherty said.

But TEMPO itself has experienced years of delays. When selected in 2012, NASA anticipated launching it in 2017. Daugherty said technical issues in the instrument’s development caused an eight-month delay. The instrument then went into storage for one and half to two years while NASA looked for a host for it. After a couple of solicitations resulted in no bids, NASA finally worked out a contract with Maxar and Intelsat. Development of the spacecraft was delayed by covid-related issues, he added.

The instrument itself cost a little more than $90 million, he said. The overall mission cost is $210 million when including the cost of integrating and hosting TEMPO on the satellite, along with support engineering and management expenses.

Commissioning of TEMPO is scheduled to begin in late May or early June, once Intelsat 40e reaches geostationary orbit, with science observations starting in October. The instrument has a 20-month prime mission but Daugherty said that the TEMPO is similar to another instrument also built by Ball on a South Korean satellite that has been operating for three years, suggesting TEMPO could also operate significantly longer.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...