GRAA NEWSLETTER
P.O. Box 1184, Greenbelt, MD 20768-1184

IMPORTANT DATES

COMMENTS FROM TONY COMBERIATE, GRAA PRESIDENT: Our March speaker was Dr. James Abshire, Goddard Senior Scientist for Laser Sensing in the Solar System Exploration Division of the Sciences and Exploration Directorate and a pioneer in laser sensing from space. His talk, entitled "NASA Goddard's Space Lidar Measurements of the Earth and Planets," traced the results and evolution of laser measurements in space over the last five decades. Jim explained the difference between lasers and lidar. Lasers use stimulated emissions to generate light, collimated into a very fine beam, which is coherent in both time and space. LIDAR (light detection and ranging) is a surveying method that measures distances using laser technology similar to radar for radio frequencies. The first use of lasers at Goddard was to optically track spacecraft for orbit determination. Lidars were subsequently put on satellites to accurately map the topography of the surface below them. By 1971, laser altimeters were being used in the Apollo program to measure the shape of the moon and the height of its craters. Almost 20 years later, the MOLA instrument on the Mars Observer spacecraft very accurately mapped the entire planet (600 million measurements) from a 400 km polar orbit. Lasers had evolved significantly in both pulse rate (10/sec vs. 1 every 20 sec) and lifetime (~1 billion vs. 1 million).

In 1996-1997, Goddard flew augmented spare parts of the MOLA system in two Getaway special cans on the Space Shuttle to simultaneously observe both the tree canopy and the ground to determine tree height and to do vegetation mapping. A Geoscience Laser Altimeter System (GLAS) was later used by Goddard's ICEsat spacecraft (2003-2009) to measure the height of the Greenland and Antarctic ice sheets and to determine how they changed over time. Ice sheets were found to be thickening in the continental center from increased snowfall while thinning at the edges due to warming. It was also noticed that the elevation over the sub-glacial lakes was changing as if the lakes were interconnected.

In 2011, the laser altimeter on the Messenger orbit around the planet Mercury found permanently shadowed north polar craters that remain very cold despite their proximity to the Sun, perhaps retaining water. The Lunar Reconnaissance Orbiter is now mapping the Moon's surface in tremendous detail using five simultaneous beams from a 50 km orbit. It has also found permanently shadowed regions where ice could be trapped.

In 2018, new missions include ICEsat 2 that will use six beams to do more accurate mappings of ice sheets. The Global Ecosystem Dynamics Investigation (GEDI) mission will be launched in 2019 to measure Earth's ecosystems (+/- 50 degrees latitude) from the International Space Station. Dr. Abshire closed by emphasizing the dramatic process in the precise mapping of Earth and other planets that he has experienced in his career and thanked his colleagues for the opportunity to work at such an awesome place like Goddard for over four decades and he looks forward to mapping icy planets like Europa in the future.

TREASURER'S REPORT: Treasurer Jackie Gasch received tax-deductible donations from: Glenn Harris, Patricia Hensel, David Manges, Raymond Mazur, Christopher Scherer, and Charles Woodyard.

THOUGHT FOR APRIL: We really start aging more quickly once we finally realize we get the same sensation from a rocking chair that we once got from a roller coaster!

FROM THE GODDARD ARCHIVES – IT HAPPENED IN APRIL: Constructed by TRW, TDRS-1 was launched on the maiden flight of Space Shuttle Challenger from Cape Canaveral, FL, at 18:30 UTC on April 4, 1983. While at the pad, issues were detected with the Challenger's main engines and repairs were begun. At the time, a severe storm caused contamination of TDRS-1, so the satellite was cleaned and launched at the time stated above. Following deployment, TDRS-1 was to be raised to its operational geosynchronous orbit by means of an Inertial Upper Stage (IUS), which consisted of two solid rocket motors - the first used to raise the orbit's apogee and the second its perigee. The first burn was successful, but the IUS went out of control during the second burn. TDRS-1 separated from the upper stage in a lower than planned orbit but was raised to geosynchronous orbit by means of its attitude control system. Initially designed for seven years, TDRS-1 was moved to a decommissioning orbit after the last functioning traveling-wave amplifier failed in October 2009, rendering it unusable for communications purposes. Decommissioning was complete on June 27, 2010.

REMEMBERING OUR FORMER COLLEAGUES:

• Roland H. Chase, of Columbia, MD, passed away on February 24^th. He came to Goddard as a Physicist in 1961 and was assigned to the Office of Space Science and Satellite Applications and then moved to NASA Hqs a year or so later. He made a special presentation at Goddard to an intra-agency technical conference on optical communications and tracking in February 1963. Later he became an Aerospace Engineer at NASA Hqs prior to retiring in 1981.
• Marion F. Federline, of Lusby, MD, passed away on February 19^th. He came to Goddard in the early '60s as a Mechanical Engineer and was assigned to the Satellite Applications & Systems Division and later the Spacecraft Integration & Sounding Rocket Division of the Office of Space Science and Satellite Applications (which later changed to the Technology Directorate). In the '70s, he was reassigned to the Mechanical Division of the same Directorate and later to the Systems Division of the Engineering Directorate prior to retiring in the mid-'80s.
• Ormond W. (Wes) McDaniel, of Gambrills, MD, passed away on February 28^th. He came to Goddard in the mid-'60s and was assigned to the Manned Flight Operations Division of the Tracking & Data Systems Directorate. In the early '70s, he worked in the Manned Flight Engineering Division of the Manned Flight Support Directorate (which later changed to the Networks Directorate). In the early '80s, he was assigned to the Analysis, Integration & Test Division of the Networks Directorate and in the early '90s moved to the NASA Communications Division of the Mission Operations & Data Systems Directorate prior to retiring in the mid-'90s.
• Wylie M. (Buddy) McMillan, of Alpine, TX, passed away on February 18^th. He was recruited by NASA in 1964 to assist in establishing the mission control center at Cape Canaveral, FL. A year or two later he transferred to Goddard and became the Assistant Director of the tracking station in Guaymas, Mexico. His next assignment, for nine years, was as Assistant Director and then Director of the Bermuda tracking station. His last assignment was in the Network Operations Division of the Networks Directorate prior to retiring in 1979 and moving back to Alpine and going to work for his wife as a cowboy.
• Robert E. Streitmatter, of University Park, MD, passed away on February 22^nd. He came to Goddard as an Astrophysicist in 1980 and was assigned throughout the '80s and '90s to the Laboratory for High Energy Astrophysics in the Sciences Directorate (which later changed to the Space Sciences Directorate and later still in 2005 changed to the Sciences & Exploration Directorate prior to his retirement in 2008).
• Arthur F. (Buggy) White, of Annapolis, MD, passed away on March 8^th. He came to Goddard as a Mechanical Engineer in the early '60s. In 1961 he was assigned to the Meteorology Branch in the Office of Space Science & Satellite Applications (which later changed to the Technology Directorate). In the '70s, he moved to several different divisions and offices over time in the Engineering Directorate. In the mid-'80s he was reassigned to the Assurance Requirements in the Office of Flight Assurance until retiring in 1995.