Twenty one students are participating in the program this summer–16 at ARL:UT and five at the university’s Institute for Advanced Technology.

Two of the apprentices have shared their summer experiences with Further Findings. First up is Jay Kapoor. We’ll hear from Kanish Mehta next week.

He graduated from Anderson High School in May 2009 and will attend The University of Texas at Austin in fall 2009. His supervisor is Christina Chomel, Engineering Scientist, Advanced Technology Laboratory. His project: Determining the Performance Boundary of the Navigation Filter for an IMU.

He explains:

Jay Kapoor

An INS consists of a main component called an Inertial Measurement Unit (IMU), some other sensors which vary depending on the accuracy and intended purpose of the unit, and the software that integrates all of the information from these various sensors to compute a navigation solution. An IMU contains three-axis gyroscopes and accelerometers. The gyroscopes measure angular velocities and the accelerometers measure linear acceleration. The software integrates the angular velocities to find the vehicle’s current orientation based on its original orientation in the inertial reference frame. The software also integrates the linear accelerations to find the vehicle’s position relative to its starting point in the inertial reference frame. The fact that the orientation and angular velocity and the linear acceleration, velocity and position are not independent is accounted for in the equations of motion in the software.

IMUs vary in accuracy depending on the cost of the unit and the intended purpose. As expected, when the performance of the IMU goes up, so does the cost. The IMU located in a car to detect rollovers and collisions simply needs to be accurate enough to detect a very large linear acceleration or angular velocity, whereas the one in the space shuttle needs to be able to detect changes in heading down to a hundredth of a degree.

The problem with an INS is that its current position is calculated from its previous position, so any errors in measuring angular velocity and linear acceleration from each measurement are continuously propagated into the next calculation of position. Thus the navigation solution begins to ‘drift’ even though it thinks that it is still ‘on course.’

The units used in the space shuttle are accurate enough for NASA but cost millions to produce. Recently, MEMS (Microelectromechanical systems) IMUs have been developed. These IMUs are a 10th of the size of a normal IMU but are much less accurate.

The goal of the project that I am working on is to create a unit that combines many of these low cost inaccurate IMUs to create a system that is equivalent in accuracy to a much larger and more expensive IMU. In addition to size and cost, an advantage is that even if one of the IMUs in the unit were to fail, the unit would still be functioning albeit a little less accurately. This kind of redundancy is not available on the Space Shuttle and IMUs can not simply be replaced in space.

My experience at ARL:UT is one that I will never forget. The project that I worked on was my first hands-on experience into the cutting edge of engineering research. It exposed me to many new concepts and programs that I had never seen before.

At times I was overwhelmed by the math behind some of the programs that my group utilized, but it gave me a glance into what I will be learning in years to come. I enjoyed working on this project because I was working on something that actually mattered for the first time in my life.

Overall, it was a fun experience and I look forward to a future career in engineering

The moon is covered with a layer of dust. NASA scientists and engineers knew that much.

But there was a hot debate about the depth of the dust.

The thin dusters thought there was a thin layer of dust that would not interfere with the landing of the Apollo lunar landing module. The thick dusters thought the dust was so deep that the lander might sink out of sight.

Not wanting to risk that humankind’s grand achievement of a lunar landing would turn into a disappearing act, NASA did what it had to do: It convened a conference of experts.

One of the experts invited was Glen Evans, a geologist from Texas. His credential what that he had done extensive analysis of the meteor crater near Odessa.

Evans was also an archeologist and a naturalist. He had worked for the Bureau of Economic Geology and had been associate director of the Texas Memorial Museum, both part of The University of Texas at Austin.

While he had a lot of experience in geology, his greatest skill was his keen sense of observation, according to Dr. Michael Collins, a researcher at the Texas Archeological Research Laboratory.

Collins has known Evans since Collins was 14 years old. He tells what happened when Evans went to Washington for the NASA conference.

As the conference wore on the thin dusters could not persuade the thick dusters nor could the thick dusters persuade the thin dusters. They were stuck in the mud.

Finally, after all the experts had their say with charts and graphs and slides and such, the floor was opened for questions.

Evans, who had not been invited to make a formal presentation, got up. He asked to see a photo of a moon crater shown by an expert.

When the slide came up on the screen, Evans described what he saw.

The crater had a classic upfold lip, created when a meteor struck the surface. He noted that a piece of bedrock as big as a boxcar had broken off and rolled into the crater.

From the photo, you could see where the rock broke from the crater, the track of its roll and where it landed. The rock was almost completely visible.

Apparently, there was a collective “aha” throughout the room.

With Evans’s insight, NASA could proceed to build a lunar lander that would land on a stable surface.

Collins said he heard the story third hand. He heard it from Gene Mears, a colleague of Evans. Mears had heard it from Eugene Shoemaker, the noted astrogeologist, who was at the meeting.

He never heard it from Evans, Collins said. He said Evans is not the kind of man who tells a story like that about himself.

Evans did acknowledge the story, however. Collins wrote the introduction for a book Evans wrote, “Wildness at Risk,” and included the moon story in the introduction. Collins read the introduction to Evans, who said that nothing had to be changed.

Peter Shelus was visiting The University of Texas at Austin campus in 1971, attending an astronomy conference. More important, he was looking for a job.

He was completing a post-doc assignment at the Manned Space Center (now Johnson Space Center) in Houston and job prospects weren’t great. NASA was laying off scientists and engineers as the basic Apollo program wound down.

It was a Friday afternoon and Shelus waited for the elevator in the Castilian apartment building. But before the doors opened, Darrell Mulholland from the university approached Shelus and said, “I hear you’re looking for a job.”

Besides a slow elevator, Shelus can also thank Neil Armstrong and Buzz Aldrin for the job he’s had for 38 years.

The retroreflector placed on the moon by the Apollo 11 astronauts.

Shelus’s job was to process the information coming from the new Lunar Laser Ranging Station at McDonald Observatory, the source of the laser beam.

Since then, four other retroreflectors have been placed on the Moon. Two by other Apollo missions 14 and 15 and two French-made mirrors carried to the surface by Soviet Union soft landers.

Now, in a matter of bittersweet timing, The University of Texas at Austin’s role in the lunar laser ranging project is ending as the 40th anniversary of Apollo 11 is marked.

The National Science Foundation (NSF), which provided support for the project when NASA dropped it more than 15 years ago, has notified Shelus that the $135,000 for the McDonald Laser Ranging System (MLRS) won’t be renewed.

“We’re essentially going out of business by probably the end of the calendar year,” Shelus said.

He understands the NSF decision—for the most part.

“We know what the lunar science is, we know the MRLS is on its last legs,” he acknowledged. The system is 20 years old and has had few upgrades.

What’s more, a brand new station is coming online in New Mexico and a French installation will re-open after shutting down for refurbishing.

Still, Shelus would like to keep his project going for another two years to collect data that overlap across the three laser stations.

“I’ve been here since 1971 so I’ve been here almost the entire 40 years. It’s been a fantastic ride,” he said. “We’ve put good data on the table, we’ve kept the experiment going and there are no regrets.”

The precise measurements of the moons orbit enabled a range of science projects.

One of the biggest science accomplishments was to test the Equivalence Principal, one of the fundamental concepts in which Albert Einstein built the General Theory of Relativity.

Among specific findings, according to NASA, the laser ranging project showed that:

• the moon is spiraling away from Earth at a rate of 3.8 centimeters a year because of the Earth’s ocean tides.

• the moon probably has a liquid core.

• the universal force of gravity is very stable. Newton’s gravitational constant G has changed less than one part in 100-billion since the laser experiments began.

Just because the Moon will no longer be a target, it doesn’t mean that the Laser Ranging Station is shutting down. Shelus and Jerry Wiant, the project’s engineer, and Randy Ricklefs, the software expert, still have work to do. Ken Harned and Anthony Garcia are observers on the laser.

The station is part of a worldwide network of lasers that bounce laser beams off satellites. What’s more, it will be involved with the two moon missions, LCROSS and LRO, launched by NASA in June.

Byron Tapley, head of the GRACE mission

We asked Byron Tapley, director of the Center for Space Research in the Cockrell School of Engineering, if there’s concern about the GRACE mission.

GRACE stands for Gravity Recovery and Climate Experiment. It is a joint operation of NASA and the German Center for Air and Space Flight. Tapley is the project’s principal investigator.

GRACE consists of two satellites that orbit the Earth in unison at an altitude of 311 miles–and have since March 2002. They measure changes in the Earth’s gravity and have provided data for scores of scientific papers.

“The collision is a significant concern for all Earth orbiting missions,” Tapley said in an e-mail message. “The GRACE satellites are at a lower altitude that the satellites that collided and in principal are not subject to immediate threat, but the pieces created by the collision will eventually come down.”

He said it will take time to determine what threat the debris might pose to the GRACE satellites,

The satellites have the capability to avoid collisions, he said.

“The assessment of the probability for impact is an on-going concern and the actions would be planned as a threat is identified,” Tapley said.

He added, “The project has a task to consider minimizing the probability of collision with other satellites.”

Mark was the director of the NASA-Ames from 1969-1977 and chancellor of the University of Texas System from 1984-1992. He started teaching at UT-Austin in 1988.

His portrait was among those of other Ames directors hanging in the hall.

I was at NASA-Ames as part of the conferences of the National Association of Science Writers and the Council for the Advancement of Science in Palo Alto, Calif., last week.

Some people toured a winery, others the Monterrey Bay aquarium and still others the Stanford Linear Accelerator Center. Me, I went to NASA.

Running into Hans Mark’s portrait goes to show that The University of Texas has strong ties to NASA, which is marking its 50th year.

Seven UT-Austin graduates have been astronauts and at any time there are several projects that university researchers have going on with NASA. Their departments range from astronomy to engineering to psychology to geology.

The university’s ties to the agency go back to the late 1950s when NASA used monkeys to help researchers understand the impact of space travel. As part of their training the rhesus monkeys were tested the Balcones Research Center, what is now the Pickle Research Campus.

Ernest Gloyna, a former dean of the engineering school worked at Balcones when the monkeys were there and remembers them … somewhat fondly.

Like human astronauts, the monkeys liked to blow off a little steam now and then.

“They’d get out and run all over the place,” Gloyna says. “We’d find their fingerprints on the glassware in our labs.”