Welcome to my government home page on the Web. From this page you can see what I work on here at NASA.

If you would like to contact me, you'll find that information at the bottom of the page.Rainbow Line


GPMMy current project is as Lead Structural Analyst on the Global Precipitation Measurement (GPM) project. GPM will eventually orbit the earth and measure precipitation over the entire planet. A previous mission, Tropical Rainfall Measuring Mission (TRMM) orbits the Earth only over the tropics region and thus does not cover the entire globe.

GPM spacecraftGPM will be made up of a "Core" satellite and a "Constellation" of up to eight other satellites, one provided by NASA and the rest provided by other agencies or governments. I am working on the Core spacecraft. A concept of this is shown to the right.

GPM is comprised of a dual-frequency radar and a microwave imager. The radar will have the capability to make detailed, three-dimensional measurements of cloud structure, rainfall, and rain rates. The microwave imager serves as both a precipitation standard and as a radiometric standard for the other GPM constellation members.

GPM is currently scheduled to launch in the summer of 2013.

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GLAST LAT My project prior to GPM was ACD, AntiCoincidence Detector. ACD is an instrument on GLAST, the Gamma Ray Large Area Space Telescope. Actually, it is part of the LAT, the Large Area Telescope, the primary scientific instrument on GLAST. GLAST is scheduled to launch in August of 2007.

GLAST will look at high-energy gamma rays from various sources, like black holes. ACD basically helps GLAST know which particles are gamma rays and which are not. To learn more, here are a few websites.

GLAST at NASA Goddard
LAT at Stanford University

The picture to the left shows a cut-away view of the LAT instrument. ACD is the "box" covering everything. Visit one of the links above to see a conceptual view of the GLAST satellite.

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HRSDM in orbitI worked on the Hubble Robotic Servicing and De-orbit Mission for a few months at the end of 2004 and beginning of 2005 before it was closed down. Bad news for me and many of the people working on it, but good news for the Hubble Space Telescope: Our new NASA administrator, Mike Griffin, decided to return to a Shuttle servicing mission.

HRSDM—or HRV, the Hubble Robotic Vehicle as we called it (much shorter to say)—was an independent vehicle that was to fly to Hubble, attach to it and then use a robotic arm on a long grapple arm to perform the servicing mission. Technically it was an extremely challenging project, but ultimately achievable we were learning. It would have been an amazing project to follow through with, but we all pretty much agree, the chances of success are better having the astronauts do the actual servicing.Rainbow Line



MLA LogoAnother recent project was the Mercury Laser Altimeter System, or MLA for short. MLA is one instrument on the Johns Hopkins University Applied Physics Lab mission called MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging). MESSEMGER was launched on August 3, 2004 on its way to Mercury. It won't arrive until March 2011 after flying 4.9 billion miles (7.9 billion kilometers).

On August 19, 2004 MLA was powered on for the first time! Everything checked out OK. That means the structure and electronics all survived launch. Of course, there was nothing to point the laser at, so we have to wait to find out if the optics survived intact. The MESSENGER launch took place on August 3, 2004 at 2:16 a.m.

MESSENGER includes eight instruments total. MLA couples an infrared laser transmitter with a receiver that measures the round-trip time of a laser burst reflected off Mercury's surface, yielding a highly accurate distance measurement and thus profiling the planet surface's topography. One goal of MLA is to measure Mercury's slight wobble.

This project is very similar to my last two projects, GLAS and MOLA, which are also laser altimeters. (scroll down a bit).
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ICESat was successfully launched on Sunday, January 12, 2003. It was launched together with a secondary payload called CHIPSat aboard a Boeing Delta II rocket at about 4:45 p.m. local time from Vandenburg Air Force Base in California. Visit Space.com for an article on the launch.

The Geoscience Laser Altimeter System, or GLAS, is the sole scientific instrument on the ICESat observatory (Ice, Cloud and Elevation Satellite). I spent about four years working on GLAS from about '98 to '01. GLAS, an integral part of the EOS program, is a satellite laser altimeter designed to measure ice-sheet topography and associated temporal changes (i.e., changes over time), as well as cloud and atmospheric properties. Operation of GLAS over land and water will provide along-track topography.

ICESat Logo

In other words, GLAS will use a laser to study the surface of the Earth, particularly how the ice at the poles is changing over time.

An informational brochure on ICESat is available in PDF format.

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My first major project was the Mars Orbiter Laser Altimeter, or MOLA for short. Jump to my MOLA Mechanical Analysis page to learn about MOLA and what I did for the project. MOLA launched in November of 1996 aboard the Mars Global Surveyor. You can find plenty of information about MGS and about the planet Mars itself if you follow the links out to the MGS website.
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Roach MOTEL Logo

The Roach MOTEL was successfully launched into space on October 29, 1998 aboard STS-95, Discovery. I suppose you might know this flight because it's the one with John Glenn's return to space.

Now I can happily report to you that the mission was a success!

The Roach MOTEL (Microgravity Opportunities To Enhance Learning) is a small, short-term project I worked on. This project was designed and built by DuVal High School, located here in Greenbelt, Maryland. The experiment sent live roaches into space in a NASA GAS Can (Get-Away Special) aboard the shuttle.

On December 8th, 1998 the roaches' habitat was deintigrated (i.e., separated) from the GAS can. The roaches were put into the can on about July 28th. We had no idea whether any of the roaches had survived. Several local TV stations and newspapers were on hand to witness deintegration. Taking a GAS can apart is no small task. There are dozens of bolts holding it all together. When the habitat was finally removed from the can, the students from DuVal peered inside to see if anything was alive. No other GAS can with a living cargo has ever returned with any of its passengers alive.

After looking into the shoe box sized and heavily insulated habitat for a couple minutes, one student said he saw something move. OK, so we wanted proof.

Well, proof came a while later after the habitat had been opened up! At least four adult roaches didn't survive. But two of the little buggers survived! They are now happily scurrying around a glass terrarium somewhere in DuVal High School.
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If you are a Stuctural Analyst and Finite Element Modeler and would like to learn some modeling tips, visit the FEMCI Page.
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If you would like to contact me, then use any of the means below. I'm generally most responsive to e-mail.

Ryan Simmons
Code 542
NASA Goddard Space Flight Center
Greenbelt, Maryland 20771

Phone: 301-286-5937
E-mail: .
Home: for personal, non-work related e-mail.

I work at NASA's Goddard Space Flight Center in Greenbelt, Maryland, a tad north of Washington, D.C.
I am a structural analyst in the Structural Dynamics Group,
... which is part of the Mechanical Systems Analysis and Simulation Branch (Code 542),
... which is part of the Mechanical Systems Division (Code 540),
... which is part of the Applied Engineering and Technology Directorate (Code 500).

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This page is maintained by
Ryan Simmons.
This page was updated March 2008.