National Environmental Policy Act; Shuttle Laser Altimeter

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

[Notice 95-099]

National Environmental Policy Act; Shuttle Laser Altimeter

AGENCY: National Aeronautics and Space Administration (NASA).

ACTION: Finding of no significant impact.

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SUMMARY: Pursuant to the National Environmental Policy Act (NEPA) of

1969, as amended (42 U.S.C. 4321 et seq.), the Council on Environmental

Quality Regulations for Implementing the Procedural Provisions of NEPA

(40 CFR Parts 1500-1508), and NASA policy and procedures (14 CFR Part

1216 Subpart 3), NASA has made a finding of no significant impact

(FONSI) with respect to the proposed Shuttle Laser Altimeter (SLA) to

be constructed at the Goddard Space Flight Center, in Greenbelt,

Maryland. SLA involves the precise global measurement of the topography

of the distance from the Earth's surface with respect to the Space

Shuttle.

DATES: Comments in response to this notice must be provided in writing

to NASA on or before December 6, 1995.

ADDRESSES: Comments should be addressed to Dr. Jack L. Bufton,

Associate Chief for Sensor Physics, Laboratory for Terrestrial Physics,

Code 920, NASA Goddard Space Flight Center, Greenbelt, MD 20771. The

Environmental Assessment (EA) prepared for the proposed SLA which

supports this FONSI may be reviewed at:

[[Page 56067]]

(a) Prince George's County Memorial Library System--Bowie Branch, 15210

Annapolis Rd., Bowie, Maryland.

(b) NASA Headquarters Information Center, Room 1H23, 300 E. Street

S.W., Washington, DC.

(c) NASA, Ames Research Center, Moffet Field, CA 94035 (415-604-4191).

(d) NASA, Dryden Flight Research Center, Edwards, CA 93523 (805-258-

3047).

(e) NASA, Goddard Space Flight Center, Greenbelt, MD 20771 (301-286-

7216).

(f) Jet Propulsion Laboratory, Visitors Lobby, Building 49, 4800 Oak

Grove Drive, Pasadena, CA 91109 (818-354-5011).

(g) NASA, Johnson Space Center, Houston, TX 77058 (713-483-8612).

(h) NASA, Langley Research Center, Hampton, VA 23665 (804-864-6125).

(i) NASA, Kennedy Space Center, FL 32899 (407-867-2622).

(j) NASA, Lewis Research Center, 21000 Brookpark Road, Cleveland, OH

44135 (215-433-2902).

(k) NASA, Marshall Space Flight Center, AL 35812 (205-544-5252).

(l) NASA, Stennis Space Center, MS 39529 (601-688-2164).

A limited number of copies of the EA are available by contacting

Jack L. Bufton, NASA Goddard Space Flight Center, Greenbelt, MD 20771,

telephone 301-286-8591.

FOR FURTHER INFORMATION CONTACT:

Dr. Jack L. Bufton, 301-286-8591.

SUPPLEMENTARY INFORMATION: NASA has reviewed the EA prepared for the

proposed SLA and has determined that it represents an accurate and

adequate analysis of the scope and level of its associated

environmental impacts. The EA, including the ``Shuttle Laser Altimeter

Ground Observer Eye Safety Analysis'', is incorporated by reference in

this FONSI.

NASA is proposing to test a low power laser altimeter instrument in

space as a pathfinder instrument for global measurement of the

topography of the Earth's land surface. Laser altimeter instruments

have been in use for several decades from airborne instrument platforms

for the purpose of terrain mapping and previous laser altimeters have

flown in space. Research results from these earlier programs indicate

the advantages of a spacebased global observations of Earth land

surface topography using the high spatial resolution and vertical

precision offered by the laser altimeter technique. Accurate

topographic information on the Earth's landforms is essential in a wide

variety of Earth science disciplines, agriculture, land-use studies,

and natural disaster (e.g., floods, erosion, landslides, volcanoes,

earth quakes, etc.) mitigation.

The principal components of a laser altimeter system are the laser

transmitter, optical receiver, and data system. The laser transmitter

sends a low powered pulsed laser bean of 1064 nano meter wavelength

radiation throughout the Earth's atmosphere toward the Earth's surface.

Each laser pulse has a temporal duration of 10 nano seconds and forms a

spot of approximately 100 meters (m) in diameter on the Earth's

surface. Reflection of laser radiation from this spot is detected at

the laser altimeter instrument by the combination of an optical

telescope and detector that constitute the optical receiver package and

covert the optical pulse into an electronic pulse. The laser pulse

time-of-flight for the round-trip from the laser altimeter instrument

to the Earth's surface and return is measured. This data then is used

to compute distance between the instrument and the Earth's surface. The

data system performs the computation of distance from pulse time-of-

flight and communicates the altimeter data to external systems and on-

board data recorders.

For laser altimeter operations, the instrument must be pointed

perpendicular to the Earth's surface in order to make accurate distance

measurements. The optical receiver is quite sensitive, since most of

the pulse laser radiation is scattered in the reflection of light from

the spot on the Earth's surface or scattered and absorbed in the

Earth's atmosphere. By using pulsed laser energy to make a series of

distance measurements (profiles) along the ground track of a

spacecraft, laser altimeter instrument can build up a global grid of

accurate surface topography.

The proposed SLA experiment will entail flying a laser altimeter

instrument as a small attached payload on the Space Shuttle. The first

flight is scheduled for November 1995 and will be a 9-day mission to

gain experience in operating a laser altimeter in space environment,

and to evaluate the sensitivity of the laser altimeter instrument for

performing the surface elevation measurement mission. The current

flight plan calls for seven operational periods of approximately 10 to

15 hours duration each during which the SLA will continuously profile

the Earth and ocean surface topography along the ground track (nadir

track) of the Shuttle. The SLA instrument operates continuously at 10

pulses per second (pps) during each period. This results in a

continuous profile of 120 m diameter optical spots (i.e., altimeter

sensor footprints) that are separated by approximately 740 m along the

ground-track of the Space Shuttle. At least one SLA operational period

is scheduled on each Shuttle flight day after flight day 2. The planned

orbit for these SLA operations is a 300 kilometer (160 nautical miles)

circular orbit at 28.5 deg. inclination. Thus the SLA measurements will

be conducted between 28.5 deg. North latitude and 28.5 deg. South

latitude. Among the land masses crossed will be Africa, most of Latin

America, Southland Southeast Asia, and much of Australia. Consequently,

no SLA operations will be conducted over the continental US north of

Cape Canaveral, Florida.

The proposed action and the no-action alternative were considered

in this Environmental Assessment (EA). The no-action alternative will

not fulfill the objective of advancing the Nation's topographic

measurement capability. Under the No-Action alternative, it will not be

possible to fully develop or space test the laser altimeter instrument

technology for an operational space-based topography system. It will

then be necessary to rely on existing photogrammetric and radar mapping

instruments which have limitations in accuracy and in interpretation of

topography data.

A review by the North American Defense Command and United States

Space Command SPADOC Laser Clearinghouse found that the SLA laser

transmitter does not produce sufficient laser energy to exceed their

damage threshold and, therefore, does not require clearinghouse

screening.

The only potential source of environmental impact from the proposed

action is the portion of the laser pulse energy which will pass through

the Earth's atmosphere and reach the surface. The SLA laser energy is

negligible compared to natural sources of optical radiation. A ground

observer safety analysis was performed for the SLA experiment and found

no substantial risk of human eye or skin injury from operation of the

SLA instrument within the range of possible Shuttle orbital altitudes.

No other environmental impacts have been identified as a result of

the EA. On the basis of the SLA EA and underlying reference documents,

NASA has determined that the environmental impacts associated with this

project will not individually or cumulatively have a significant effect

on the quality of the environment. NASA will take no final action prior

to the expiration of the 30-day comment period.

[[Page 56068]]

Dated: November 1, 1995.

William F. Townsend,

Deputy Associate Administrator for Mission to Planet Earth.

[FR Doc. 95-27449 Filed 11-3-95; 8:45 am]

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