Findings

CREDIT: J. T. Dimos et al., Science, 29 August 2008, p. 1218

by Greg Miller

If you've been reading science news stories for the past couple of years, you've probably heard that induced pluripotent stem (iPS) cells are the next big thing. They have many of the same talents as embryonic stem cells, but they don't carry the ethical baggage. That's because iPS cells don't require the destruction of embryos: They can be created by reprogramming skin or other cells from any adult--including patients with nervous system disorders. Although iPS cells may one day be used as treatments, right now many researchers are using them primarily as research tools. This morning I stopped by a session on iPS cells to get a sense of how things are progressing.

Allison Ebert of the University of Wisconsin, Madison, gave a nice overview of a flurry of recent papers demonstrating the use of iPS cells derived from neurological patients. The first was a 2008 Science paper that used skin cells taken from an 82-year-old woman with amyotrophic lateral sclerosis to create iPS cells and coax them to differentiate into motor neurons. Earlier this year, Ebert and colleagues reported in Nature that they'd derived iPS cells and created motor neurons from a patient with another neuromuscular disorder, spinal motor ataxia (SMA). She and her colleagues are studying these cells for clues about why motor neurons die off in SMA. One early hint, she reported, is that genes involved in apoptosis, or programmed cell death, seem to be upregulated in these cells.

Ricardo Dolmetsch of Stanford spoke about his group's efforts to create iPS cells from patients with a variety of autism-related disorders and examine the resulting neurons for abnormalities in gene expression, fine-scale anatomy, and electrophysiology. Jason Chiang, a fifth-year graduate student at Johns Hopkins University, described his work with iPS cells from two people with trisomy 13, a profoundly debilitating neurodevelopmental disorder for which there is no good animal model. Chiang presented evidence that defects in cell signaling pathways involving Wnt proteins, key regulators of neural development, may be involved in the neurological aspects of the disorder.

Dolmetsch summed up the state of the field at the end of his talk, throwing up a slide from a tech consulting firm that traces (in a slightly tongue-in-cheek fashion) the stages of a new technology as it progresses from the "peak of inflated expectations" to the "trough of disillusionment" to the "slope of enlightenment," finally arriving at the "plateau of productivity." Dolmetsch used a laser pointer to indicate where he sees the field: just beginning to come down from the peak.

That seems about right. Despite the great potential iPS cells hold for unraveling the biology of neuropsychiatric disorders and testing potential treatments, many serious questions remain, not the least is how well the findings will translate to real patients. As Dolmetsch said: "I hope the trough isn't too deep."

by Richard A. Kerr

A near-infrared image of Cabeus crater, taken from Palomar Observatory after the LCROSS impact today. No ejecta are visible from the image, but further analysis may reveal subtle indications of the crash. (Credit: Palomar Observatory/Caltech)

NASA officials and scientists spent the better part of an hour in this morning's press conference patting themselves on the back. The LCROSS mission in search of lunar water was a great success, they said, all the while ignoring a very large elephant in the room: No one among the millions watching as a 2-ton hunk of metal slammed into the moon could see the much-ballyhooed spray of dust and debris that they had been told to look for.

Even LCROSS scientists have seen nothing of a debris plume. "I'm not necessarily surprised," said LCROSS principal investigator Anthony Colaprete of NASA's Ames Research Center in Mountain View, California. In exploration, "you just never know how these things are going to go. We just have to go back with a finer-tooth comb." Colaprete's dogged optimism is grounded in enticing spectroscopic changes detected around the impact site. Determining whether it was water will take weeks or months of data combing.

Actually, Colaprete had warned his colleagues, at least, about the possibility of a no-show debris plume. "It's a very unproven and highly unpredictable science, impact cratering," he told an audience at the Lunar and Planetary Science Conference last March. Impact modelers working for the team had struggled to simulate the impact of a cylindrical--not a simpler spherical--object, and one that was hollow, not solid, like the LCROSS impactor. Plus, it smashed into a surface of unknown shape and composition. LCROSS was "the most challenging impact modeling I've ever done," said Erik Asphaug of the University of California, Santa Cruz, at the time. There were just too many unknowns for him to be entirely comfortable with his results; impact on the odd unseen boulder, for example, could have sent most of the debris into the crater wall instead of into the sky.

LCROSS scientists may yet extract a debris plume from the data, but "the spectra is where the information is" about any water, Colaprete said, referring to spectral colors in the visible, infrared, and even ultraviolet returned by the trailing LCROSS spacecraft and by the Lunar Reconnaissance Orbiter. Some of these showed intriguing blips from the impact flash and the still-warm crater. There were also spectral changes above the impact site between pre- and postimpact. "What do these little blips mean? I don't know," Colaprete said. "I'm just glad they're there. We're going to work on this feverishly." Even so, no public word about water will be forthcoming before the December meeting of the American Geophysical Union, he said.

Start rooting now for the blips.

by Richard A. Kerr

Image of the LCROSS target crater before impact (top), and the last visible-light photo from the spacecraft (bottom). Although intended to produce a visible plume of ejecta, the impact has so far not yielded anything quite so spectacular. (Photos: NASA)

I didn't see anything. Did you? After the 2-ton upper stage of an Atlas rocket slammed into the lunar surface at 7:31 EDT this morning, no one at NASA admitted to spotting the expected spray of dirt and debris rising into the sunlight over the moon's Cabeus crater, as depicted so dramatically in the LCROSS mission overview video. The impactor most certainly plowed into the dark, frigid shadow inside Cabeus as planned, and the nine instruments on the trailing LCROSS spacecraft returned all the planned data. But no flash was reported at the moment of impact, and no debris could be seen. The science team's only report was "confirm crater in mid IR [infrared]," an apparent sighting of the impactor's hole in the ground. LCROSS itself then hit the moon, with mission control reporting a "loss of signal."

If the rocket impact failed to throw sufficient debris out of the lunar shadows to be detectable, it would not come as a complete surprise. Calculating just how the impact would excavate a crater in the lunar soil and rock "was the most challenging impact modeling I've ever done," Erik Asphaug of the University of California, Santa Cruz, said last spring. If high-rising ejecta were a no-show, there will be little chance of detecting minerals that could have been hydrated by subsurface ice. On the bright side, any water that turned to vapor would have expanded well beyond any solid ejecta and surely have risen into the sun, where some of LCROSS's instruments could have seen it. One can hope.

For those of you who want to follow the event blow-by-blow as NASA sends a rocket crashing into the moon on Friday, 9 October:

• 6:15 a.m. EDT  NASA TV begins a live broadcast of the mission. Watch here.
• 7:31 a.m. EDT  Lunar impact!
• 10:00 a.m. EDT  NASA postimpact news conference.
• 12:00 p.m. EDT  Science's resident space expert Richard Kerr will blog his preliminary analysis of the mission's findings.
• 3:00 p.m. EDT  Richard Kerr will blog a full wrap-up and analysis of the LCROSS mission.
• 4:00 p.m. EDT  Live Facebook chat with Richard Kerr. Submit your questions now, and follow the chat here.

We will also be covering the event on Twitter.

Don't expect this one to win any MTV music video awards, but the LCROSS mission has its own theme song. NASA credits the tune to LCROSS Deputy Project Manager John Marmie and his friend Jeff Petro. Check out the video below. It's sure to become a staple of late-night NASA TV.