People are talking about NASA Administrator Charles Bolden's clash with a House oversight panel over America's space program. Bolden testified Thursday before the House space science subcommittee about NASA's 2015 budget request. Here's what the fight was about in 8 questions and answers.

1. What started tensions rising?

Bolden said "the critical need for this nation in space" is giving NASA all it has requested to keep on track a program supporting American companies developing spaceships to carry astronauts to the International Space Station.

NASA wants almost $850 million for a so-called "commercial crew" next year (a $150 million increase), while cutting the Space Launch System (SLS), a deep-space rocket many lawmakers support, by $219 million.

2. Why did things get heated?

Subcommittee members told Bolden they support getting American astronauts off Russian rockets, especially given the tension over Crimea, but Bolden said the current situation is Congress's fault.

"This committee, this Congress, chose to rely on the Russians," Bolden said, "because they chose not to accept the president's (earlier) recommendation for full funding for commercial crew. You can't have it both ways." By that, Bolden meant Congress has cut commercial crew to fund SLS for years.

U.S. Rep. Mo Brooks (R-Huntsville) makes his points while debating NASA Administrator Charles Bolden during a hearing March 27, 2014. (House Subcommittee on Space, Science and Technology)

3. Who challenged Bolden?

Several representatives, including U.S. Rep. Mo Brooks (R-Huntsville). Brooks said they were "somewhat astonished" by Bolden blaming Congress for NASA's dependence on Russia.

The Obama administration canceled the Constellation rocket program in 2010 that could be close to an American spaceship by now, Brooks said, and it mothballed the space shuttle fleet.

Bolden challenged the committee on that point.

"The decision to phase out the shuttles was not made by the Obama administration," Bolden countered, saying former president George W. Bush made that call.

4. What was Bolden's response to Rep. Brooks' call for NASA's plan if Russia stops selling America rides before a commercial crew is ready?

There is no plan, Bolden said, adding, "If I don't have commercial crew and I can't get to (the space station), I don't need (the Space Launch System) and Orion (crew capsule)."

Bolden said the space station would probably be shut down, and he would ask President Obama to cancel both SLS and Orion.

5. Where did that come from?

Bolden said NASA has a three-part strategy to get to its big destination of Mars: 1) experiment on the space station in low-Earth orbit, 2) learn more about deep space technology by capturing an asteroid between the Earth and moon, and 3) use SLS and Orion to go to Mars.

"We're not ready" to go to deep space, Bolden said, adding again, "I don't need a Space Launch System if I can't get my crews to low-Earth orbit."

6. Is there really a threat Russia could stop selling American astronauts rides?

Bolden and NASA say no; both sides need and want the partnership and have continued it in other tense times.

The station couldn't operate without America, Bolden said, and the international partners would probably shut it down if Americans weren't there. That would mean, again, no three-part strategy and no need for SLS.

7. What's the real fight here?

Long-term, the issue is America's mission in space. How much will it invest in deep space exploration, and where will it find the money?

It's about direction and choices, but the immediate answer is money. The subcommittee doesn't feel it has more to give NASA next year, so what one program gets, another loses.

8. Is there a way forward?

Congress wants NASA to narrow the space companies it is helping financially from three to one. Bolden would rather not until he absolutely has to.

A sole-source contractor can get demanding, he said. But cutting from three to two is a good bet this year.