MOSCOW - When NASA's Deep Impact spacecraft hurls a barrel-size probe at a comet millions of miles from Earth on July 4, Marina Bai of Moscow will take it very personally.

The 45-year-old mother of two is so upset about the space agency's scientific assault on the celestial body that she has taken the unusual step of suing NASA in Moscow courts. Her lawsuit seeks to block the launch of the probe and to recover $311 million in "moral" damages.

Bai, a self-published author and spiritualist, said that she couldn't sleep after watching a television report about the Deep Impact mission, which is led by a team of astronomers at the University of Maryland, when it was launched Jan. 12.

"Somewhere deep inside me a voice told me the whole mission had to be stopped," she said in an interview yesterday. "I fear that it could have an impact on all humanity."

In court papers, Bai asserts that Deep Impact will "infringe upon my system of spiritual and life values, in particular on the values of every element of creation, upon the unacceptability of barbarically interfering with the natural life of the universe, and the violation of the natural balance of the universe."

Dolores Beasley, a spokeswoman for NASA, said it would be "inappropriate" to comment.

A spokesman for the U.S. Embassy in Moscow said the ambassador had not been officially notified of the lawsuit.

"We haven't received notice from the Ministry of Foreign Affairs on this matter, and therefore we have no comment," said Edward Salazar, the press attache.

Steven P. Maran, a spokesman for the American Astronomical Society and author of Astronomy for Dummies, reacted to Bai's claims with humor yesterday.

"I get dizzy just thinking of this lawsuit," he wrote in an e-mail. "But I don't think the outcome is written in the stars."

Plans call for Deep Impact to launch an 820-pound copper projectile at the 2.5-mile-wide comet Tempel 1 on Independence Day. The 23,000-mph impact is expected to generate a force equivalent to almost 5 tons of TNT and could blast a hole in the comet's icy surface the size of the Coliseum in Rome.

Cameras and sensors on the spacecraft will record the event in an effort to help scientists determine the structure and chemical composition of Tempel 1. Comets are thought to be bits of ice, dust and rock left over from the formation of the universe about 14 billion years ago.

Scientists have dismissed fears that the collision might break up or divert the comet, comparing the impact to a mosquito striking a Boeing 747.

But Bai fears the bombardment could disrupt mystical forces. More practically, she added, it might create an open season on celestial objects by the world's spacefaring nations.

"If the Americans can study comets with the help of bombs, why not the Chinese?" she asked. "Americans want to be ahead of everybody. And maybe that's good, but not in this case. It's a barbaric method, to study the universe with bombs."

Bai's attorney, Alexander V. Molokhov, said the damage claim was calculated under Russian law, which allows plaintiffs to recover an amount equal to the cost of the undertaking that allegedly does the harm.

David vs. Goliath lawsuits in which individuals demand huge sums from large institutions are relatively rare in Russia, where the court system is notoriously subject to financial and political pressure.

Molokhov said Bai's lawsuit breaks legal ground.

"Americans are used to such suits," he said. "But it is absolutely new to this country."

At first, Moscow's Presnensky District Court refused to hear the case. But Bai appealed to the Moscow city courts. In May, city judges ordered the Presnensky court to bring the case to trial. No date has been set.

Despite the Russian Space Agency's partnership with NASA, a small Kremlin-controlled newspaper, The Russian Weekly, has written an extensive, sympathetic article about Bai's lawsuit. "How Can You Stand By When Your Star is Threatened?" the paper asked.

NASA has refused to acknowledge the case, Molokhov said.

“They look at us as a Third World country, so why react?" he said. "From my point of view, the longer they keep silent, the stronger our case. They have to prove that their project is safe."

Deep Impact borrowed its name from a 1998 science fiction movie about a comet on a collision course with Earth. In the movie, astronauts blow up the comet and save the planet.

Bai said she is more interested in blocking the planned impact on Tempel 1 than collecting damages. If she wins the case, she said, her nonprofit Transformations fund will spend the award on environmental and social programs.

"Unlike the oligarchs, I'm not going to buy a soccer team with the money," she said.