WASHINGTON — NASA should focus on building the next full-scale Earth-observing satellite in its long-running Landsat series and forget about a proposed interim capability to ensure continuous coverage in the infrared bands, House and Senate lawmakers said in separate 2016 spending bills drafted in June.
To different degrees, the House and Senate Appropriations committees backed NASA’s plan to build Landsat 9, which would be a rough copy of the visible- and infrared-imaging Landsat 8 craft that launched in 2013. But both committees were in lockstep in directing the agency to scrap plans for a $180 million infrared-only backup satellite called the Thermal Infrared Free Flyer (TIR-FF) that would launch in 2019.
The White House is seeking a combined $80 million next year for Landsat 9 and TIR-FF. A House spending bill passed June 3 would provide only about $33 million, specifically for Landsat 9, while a bill approved June 11 by the Senate Appropriations Committee provides $100 million with instructions to accelerate that satellite, now scheduled to launch in 2023.
Landsat satellites collect medium-resolution Earth images as part of an unbroken record that dates back 43 years. Under the current program model, NASA builds and launches the satellites while the U.S. Geological Survey is responsible for operations and data distribution.
In April, Michael Freilich, NASA’s Earth science director, told SpaceNews the agency conceived the TIR-FF mission because Landsat 8’s thermal-infrared instrument, a late addition to the program, is not performing to specifications and was in any case designed to work only for three years. Although Landsat 7 has a thermal imaging capability, that satellite is 16 years old and is likely to be shut down in 2019, he said.
Landsat 8 was originally designed as a bare-bones Landsat 7 replacement that lacked a thermal-infrared imaging capability. But Congress, under pressure from western U.S. states to continue making thermal-infrared measurements for water resource management, directed NASA to add that capability to the satellite at a relatively late stage of the program. Freilich said NASA, in order to keep the satellite on schedule, did not build the usual longevity into the sensor.
In addition to providing a backup thermal-infrared imaging capability, TIR-FF, in combination with the European Sentinel 2A Earth observing satellite slated to launch June 23, would effectively replace the full capability of Landsat 8 should it fail prematurely.
But the Senate Appropriations Committee, which like its House counterpart is abiding strictly by spending caps set in the Budget Control Act of 2011, said the best risk insurance is Landsat 9. Accordingly, the Senate lawmakers provided no funding for TIR-FF and directed the agency instead to accelerate the Landsat 9’s launch by three years, to 2020.
The House bill similarly denied funding for the free flyer and requested a report from NASA on the cost and milestones toward launching Landsat 7 “no later than 2023.”
It is not clear whether the House and Senate will have a chance to reconcile their proposed 2016 budget bills. The Senate’s Democratic minority is threatening to block consideration of spending bills on the floor of that chamber.
Samuel Goward, a professor at the University of Maryland in College Park and former principal investigator on Landsat 7, questioned why NASA is pursuing TIR-FF in the first place when it faces the larger problem of having only one fully capable Landsat satellite on orbit. A single Landsat satellite provides repeat coverage on 16-day cycles, but NASA has long been able to maintain at least two on orbit, and users have grown accustomed to the resulting eight-day repeat cycle.
“If you’re going to do a free flyer with the Thermal Infrared Sensor onboard, why not put an optical component on the same system?” Goward said in a June 17 interview. “That’s a pretty low-cost solution, or it should be.”
But Goward acknowledged that if Congress is unwilling to fund TIR-FF on budget grounds, it is unlikely to support building another full-scale Landsat satellite to accompany Landsat 9 on orbit.
NASA spokesman Steve Cole did not immediately reply to a request for comment June 17.
NASA stood up a Landsat 9 program office in April at the Goddard Space Flight Center in Greenbelt, Maryland, which will build the spacecraft’s thermal-infrared camera, as it did for Landsat 8. Other procurement decisions are pending. NASA hopes to finalize an acquisition strategy by Sept. 30, Freilich said.
Ball Aerospace & Technologies Corp. of Boulder, Colorado, built Landsat 8’s main visible-spectrum camera, the Operational Land Imager, while Orbital ATK of Dulles, Virginia, provided the spacecraft bus.