More than 60 worried owners of lunar real estate have written to the White House warning Bush not to let astronauts soil their property.
The campaign is being coordinated by the Kurier, a local newspaper in the Sauerland region, an area of western Germany noted for its rolling hills and pastures.
Three years ago more than 1,200 people there paid 30 to 40 marks (15 to 20 euros, or 18 to 24 dollars, in today's money) each to buy pieces of moon rock in parcels of 700,000 square metres.
"It was the big party-joke of the day, along the lines of giving somebody the moon," the Kurier's editor Torsten-Eric Sendler said.
"They got their certificates of ownerships, then we heard nothing."
The parcels were bought from Dennis Hope, a US entrepreneur who claims he secured legal ownership of the moon and most other bodies in the solar system 20 years ago by exploiting a loophole in the 1967 UN Outer Space Treaty.
His Lunar Embassy promises buyers a deed, a site map, a copy of ownership filed with the US government, and a 30-day money-back guarantee.
But when Bush in January announced plans to send US astronauts back to the moon and build a lunar launch pad for manned trips to Mars, "worried (Kurier) readers asked us what would happen to their property."
Sendler told them to write to the White House. Earlier this week the paper sent off a first batch of 60 to 80 letters, but more are arriving every day.
Some warned Bush that while they didn't mind a space station being built, "they didn't want landing flags or rusting vehicles dumped on their land."
Others refused permission for Americans to step foot on their property or suggested they should build fences to protect them.
"I hope the White House will reply," Sendler told AFP, "although I suppose there are more important questions around than property on the moon."
Meanwhile, the paper is considering asking for legal clarification on the status of the moon estate.