Did a Soyuz spacecraft cause the deaths of hundreds of endangered saiga antelope in Kazakhstan this week?
Some ecologists think so, although scientists and the Kazakh authorities remain skeptical.
Officials say the carcasses of at least 543 saiga antelope have been found in northern Kazakhstan's Qostanai region since May 21, the latest reported mass death of the critically endangered animal.
And the fact that some 120 of the carcasses were discovered near the village of Sorsha -- the same location where a Soyuz capsule carrying a Russian-American crew from the International Space Station landed in April -- has sparked suggestions the animals may have been poisoned by chemicals left behind by the craft.
Likewise, in an interview with RFE/RL's Kazakh Service, ecologist Musagali Duambekov suggested that the mass deaths could be connected to the Baikonur space-launch site in central Kazakhstan.
"My personal opinion is that it is connected with human activity [and] that it is due to an anthropogenic factor," he said. "It could be from chemical elements left from space rockets that fly over this place, or from other chemical factors, such as the extensive use of fertilizers, which are very harmful."
In the past, Kazakhs have blamed toxic elements from the fuel used in launches from Baikonur for environmental damage and contamination in the region.
Nonetheless, although some 12,000 dead saigas were found in western Kazakhstan in May 2010, and 450 more in May 2011, no link with launches from Baikonur has ever been officially established.
The saiga carcasses are hauled away.
Meanwhile, Kazakhstan's Agriculture Ministry says that test results determining the cause of the latest deaths are expected in two weeks.
"All our specialists are on the spot right now, taking probes for laboratory analysis," said Marat Begimbetov, the head of the Qostanai Oblast's Department of Forestry and Hunting. "We have to find what caused the death of the saiga antelope. There have been 543 dead antelope found so far, but there could be more."
Independent researchers, however, are skeptical that the mass antelope deaths are connected to Baikonur or Soyuz capsules returning from the International Space Station.
Eleanor Milner-Gulland, the chairwoman of the Saiga Conservation Alliance, a network of researchers and conservationists working to study and protect the antelope, says the antelope discovered this week were probably killed by the same ailment that accounted for previous mass deaths -- a digestive disorder caused by eating too much rich and wet forage.
"It's exactly the same timing as the last two years," she says. "And in the last two years, it's quite clear that it's likely to have been [connected to the] forage. So although we need to investigate the suggestion about the [spacecraft] fuel, it's just one of a number of potential explanations. We do seem to have evidence over the last two years of issues to do with very rich forage around the birth time."
Milner-Gulland adds that the fact that most of the dead antelope were females supports such an explanation.
"What happens is that the females give birth and they are under great nutritional stress because they're producing milk and they've just given birth," she says. "So they seek out very rich pastures and that's why the females are particularly suffering. And then the babies tend to die later from starvation."
With its bulbous, tubular nose, and bulging eyes, the saiga antelope is one of the world's strangest-looking mammals.
The antelope is mostly found roaming in Kazakhstan and Russia's Republic of Kalmykia. It has also been sighted in Uzbekistan and Turkmenistan.
In the 1980s, there were more than 1 million saiga antelope, but its population decreased by more than 90 percent over a 10-year period.
PHOTO GALLERY: Images of the saiga
The species has recovered somewhat but remains on a list of critically endangered species kept by the International Union for the Conservation of Nature
"Since about 2005, some of the saiga populations [have] started to recover," Milner-Gulland explains. "Particularly, the population affected now -- which is the Betpak Dala population in [central] Kazakhstan -- has a lot of investment from the Kazakh government and from international NGOs.
"It seems to be doing quite well. So now we're up to about, say, 100,000 saigas [in Kazakhstan]. Compared to the number of saigas that we have in Kazakhstan, 500 [deaths] might not seem very many. [But] these are females that had just given birth and any mortality in the saiga population is not good."
The antelope has also come under pressure because of the collapse of economies across its habitat, which has led to a dramatic increase in poaching for its meat and horns, an ingredient in traditional Chinese medicine.
RFE/RL’s Kazakh Service contributed to this report