NASA's chief scientist Ellen Stofan on Tuesday doubled down on her prediction that the agency could uncover life outside Earth in the next 10 to 20 years.

"With future technology and instruments currently under development, we will explore the solar system and beyond and could indeed — perhaps in as little as 10 to 20 years — discover some form of life, past or present," Stofan told House lawmakers.

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Testifying before the House Science Committee, Stofan's statement appeared more nuanced than her prediction back in April, when she said she believed the world would find "definitive evidence" in that time period. Her statement Tuesday also included the caveat that the evidence could come in the form of past life and fossils.

A day after NASA announced that it had uncovered the "strongest evidence yet" that water sometimes flows on Mars, Stofan said the red planet is the agency's primary target for the search for life inside the solar system. She also noted that President Obama's 2016 budget includes funds to develop a mission to Jupiter's moon Europa, a body with more water than Earth.

Any sign of life on Mars would likely come in the form of fossilized microorganisms and would probably require human field geologists to uncover them, Stofan predicted.

"I can tell you it may be hard to find. That's why I believe it will take human explorers — geologists and astrobiologists — who can move quickly and make intuitive decisions on their feet to identify it."

NASA has recently focused on building up commercial space flight for low-Earth orbit, while it develops a launch system to take astronauts to Mars in the 2030s at the earliest.

The House committee noted the government spent an estimated $57.5 million on NASA astrobiology funding in FY 2015, with predictions of a slight boost in 2016.

Since Congress killed NASA's Search for Extraterrestrial Intelligence program in 1993, the government has focused on finding the fingerprints of life within the solar system, as well as searching for exoplanets circling other stars that have comparable characteristics to Earth.