Boosted into space March 8, the modified HDI 5000 built by ATL Ultrasound now waits for a crew capable of running it. Budget cuts have reduced the size of the crew of the International Space Station (ISS), sidelining research with the space-faring ultrasound scanner for a year or more.
"I would have preferred to fly it closer to when it would be used, because then we could have gotten more upgrades into it," said David S. Martin, senior scientist for ultrasound at NASA's Johnson Space Center in Houston.
There is another concern about having the scanner sit idle in space. The longer the unit orbits the earth, the greater the possibility that radiation or some other force will cause a malfunction. If something does go wrong, troubleshooters on earth will use ATL's UpLink remote system diagnostics program, which has been customized for space communications, to find the problem. Circuit boards have been located in easily accessible locations within the body of the scanner, so replacement parts, flown in on a future supply mission, could be swapped in, if necessary. Components would be taken from an identical backup unit or either of two training units on earth.
In the meantime, the space station project has provided some benefits here on the planet. Finding ways to reduce the system's volume by 80% and weight by 60% bodes well for ATL's efforts to construct powerful yet compact and lightweight scanners. Some of this achievement, however, was accomplished in ways not appropriate for terrestrial systems. Locked into an equipment rack, as it is in the Destiny research laboratory of the ISS, the box surrounding the electronics could be eliminated-as could the wheels. And not all of the reengineering has everyday applications. Developments to protect the electronics from radiation damage have limited application here, since cosmic rays, the source of this damage, never reach the earth.
HDI 5000 was preceded into space by other scanners flown on the U.S. space shuttle and Russian space station, Mir. These were relatively primitive. None offered phased array, color flow, or tissue Doppler imaging, according to Martin.
"They left some questions unanswered," he said.
The HDI 5000 now in orbit was designed to address those questions, including the effects of microgravity on blood flow, the heart, and other organs as well as a range of musculoskeletal and cardiovascular functions. The answers may be crucial in planning a mission to Mars, which could last two or more years.
