The head of NASA appealed to Congress on Friday to put more money into restoring America's ability to send astronauts into space instead of relying on Russian rockets.

In an open letter, published in Wired magazine and titled "Don't Make Us Hitch Rides With Russia. Love, NASA," Charles Bolden said the US government has essentially funded Moscow instead of pouring money into its own aerospace industry back home.

"Every dollar we invest in Moscow is a dollar we're not investing in American businesses," wrote Bolden, a former astronaut and the current administrator of NASA, the US space agency.

The US space shuttle program closed down for good in 2011 and commercial industry -- with the help of NASA funds -- is racing to build new spaceships to ferry astronauts to the International Space Station by 2017.

"Since 2010, the president has received approximately $1 billion less than he requested for NASA's Commercial Crew initiative," Bolden wrote.

"During this time we've sent $1 billion to Russia."

Without a US spaceship to carry humans to space, the world has had to rely on Russia for transport aboard its Soyuz capsules.

"On a per-seat basis, it costs approximately $81 million to send an American astronaut to the Space Station on the Russian Soyuz spacecraft," Bolden wrote.

"By comparison, it will cost $58 million per seat to send our astronauts to the Space Station on Boeing's and SpaceX's spacecrafts, once they are certified."

The letter concluded by urging lawmakers to funnel more money into US efforts to return to spaceflight.

"Just recently, NASA was left with no other choice but to write a $490 million check to our Russian counterparts so that we can get our own astronauts to the Space Station. It doesn't have to be this way," Bolden said.

"Congress can and should still fix this by investing in Commercial Crew."