Lighter-than-air Platforms (Blimps and Aerostats) for Oceanographic and Atmospheric Research and Monitoring

James H.W. Hain Associated Scientists at Woods Hole

Box 721 3 Water Street Woods Hole, MA 02543

Abstract-Lighter-than-air platforms (airships and aerostats) have been flown in a variety of research applications for more than a decade. The capabilities offered by these platforms are both unique and complementary to existing oceanographic and atmospheric research platforms. The addition of these platform types to the national aircraft research fleet is envisioned as a multi-agency, multi-user program based on the UNOLS or UCAR models. The identification of cost options, mission requirements, and user community is underway.

This paper provides examples of research activities to date, describes platform capabilities, and gives an update on the effort to develop this class of platforms for scientific research and environmental monitoring.

-Cr--- Station-Keeping Abiiity -

I. INTRODUCTION

Progress in science is closely linked to advances in platforms, instrumentation, and technology. The past decade has seen major advances in development of manned submersibles, remotely operated vehicles (ROVs), autonomous unmanned vehicles (AUVs), satellite-based systems, and others. One intriguing area, yet to be developed to full potential, is that of lighter-than-air platforms. These are of two principal types: 1) airships or blimps--propelled aircraft capable of carrying scientists and equipment, and 2) aerostatwethered balloons capable of carrying antenna arrays, instrument packages, and sensors. Both platform types can operate effectively to altitudes of several thousand feet. These platforms have been used in studying atmospheric properties, testing sensors, ground-truthing satellite data, carrying antenna and camera arrays, and studying whales and other endangered species.

There is currently an open niche--and requirement-in the nation's oceanographic, atmospheric, and boundary layer platform capabilities. There is a need for low, slow, and quiet-with extended airborne station-keeping capabilities. In recent years, the concept of a multi-agency, multi- investigator consortium, based perhaps on the UNOLS or NCAR models, aimed at increasing availability and reducing cost on this class of platforms has been discussed. The unique capabilities of these platforms would provide information not otherwise available-and complementary to other platforms (Fig. 1). An effort is now underway to coordinate and cany forward a cohesive effort to identify the user community, identify and prioritize research missions, identify platform options and costs, and define mission requirements.

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Fig. 1. Addressing logistically challenging ocean and atmospheric science problems requires matching the platform to the project. Airships have a capability that is distinct from, yet complementary to, that of ships, other aircraft, and satellites. Airships offer a combination of perspective, resolution, flexibility, and station-keeping ability that is applicable to a wide range of missions. They can also play a role in multi-platform efforts.

11. SCIENTIFIC USE OF AIRSHIPS

My own research interests include behavioral observations on endangered marine mammals from an effective yet non- obtrusive vantage point. For this work, I and colleagues have used airships since 1989. To date, we have made more than 50 flights, and flown 300 hours and 5,000 miles in the course of overwater surveys for studies on whales and other protected species. In addition to conventional behavioral observations using hand-written or tape-recorded notes, this

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effort has included remote sensing, video-data acquisition, and the use of night-vision devices. Early results and capabilities were summarized in [I], and research results reported in [2,3].

Other oceanographic sampling in the early 1990s included surface water sampling, phytoplankton hauls, temperature and salinity profiling, deployment of current drifters, and geophysical surveys [I]; while boundary layer and atmospheric sampling included measurement of the radiative transfer through the lower atmospheric boundary layer and ocean-surface flux measurements [4,5,6]. An airship was also used for studies of aerosol distribution and particle formation in the marine boundary layer [7,8]. In 1999, an airship was used to for sampling to validate computer models predicting movement of the exhaust clouds of Titan IV missiles [9]. In England, the Defense Evaluation and Research Agency used an A-60+ Lightship for trials of a prototype airbome radar to detect buried mines [IO].

111. SCIENTIFIC USES OF AEROSTATS

To date, the aerostats used for research have typically been used to lift c a m e r a d t h still and video [11,12]. Meterologists have also used aerostats for lifting sensors to measure particulates and ozone in urban plume studies [ 131. In recent years, our group has been experimenting with lifting antennas employed in tracking and monitoring whales and other species to which small transmitters have been attached (by elevating the antennas, line-of-sight radio range is considerably increased) [Fig.2]. Rapidly evolving technology allows us to evaluate fiber optics as well as RF for uplinking control functions and downlinking system monitoring and data relay functions. The use of aerostats for scientific research is in an early stage, and evaluation and development of methodologies and capabilities is underway.

IV. COST

One factor that has been an impediment to the more widespread consideration of airships as scientific research platforms has been cost. Subsequently, I examined this factor for a July 1998 meeting of the University-National Oceanographic Laboratory System (UNOLS). Table I and Fig. 3 illustrate that airships, like existing research platforms, come in a variety of sizes, capabilities, and costs. While the cost estimates have likely changed somewhat since this table was prepared, a reasonable conclusion is that the ranges of cost/capabilities are not dissimilar from other platforms. Secondly, as with other platforms, technology and capability continue to advance-and, at least in some cases, cost is decreasing.

Fig. 2. An aerostat currently employed for research applications. This 29 ft balloon, with a 1500 m' helium volume, can be used to lift cameras, antennas, and other sensors to altitudes of lo00 ft.

Table I. Airships are available in a range of sizes, capabilities, and costs that compare in range to oceanographic research vessels and aircraft. Similarly, increased endurance and payload is associated with larger ships and higher costs. Conversely, a project in a nearshore area with a light payload can utilize a smaller, less expensive ship. Not all cells are filled in, as it is difficult to directly compare costs. Costs are approximate based on 1997 estimates.

# COST/ COST/ DAY FLTHR

# PLATFORM LENGTH scI CREW

WHO1 Ship

274' $1 7,000 Atlnntir NOAA A l h n t r n r r I V 187' 15 18 $ 1 2 , ~ ~

156 15 15 $8,500

106' 9 5 $4,700

NOAA Delaware I1 (contracted) AhoI-I "

Aircraft

3-4 3 $3,500 CG HHdOJ Helicopter NOAA P-3 6-8 4-5 $3,100

4-5 2 $840

3 1-2 $300

NOAA Twin Otter (contracted) c-3.37

Skyship 600 4-5 2 $10,OOo

Lightship A-150

2 1 $6,000 Lightship A-60+

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Fig. 3. A new generation of airships is available for scientific research missions. Capabilities and costs can be matched to mission requirements and funding levels. The types of airship include: (top) the Lightship A-60+, a 132 ft, 2000 m' helium volume ship carrying 1 pilot and 2 scientists for 4-6 hr flights; (middle) the Lightship A-150. a 165 ft, 4500 m' helium volume ship carrying 1-2 pilots and 4-5 scientists for 8 hr flight days; and (bottom) the Skyship 600, a 194 ft, 6000 m' helium volume ship carrying 2 pilots and 4-5 scientists for 8-10 hr flight days.

V. MISSION AND USER COMMUNITY

In times of limited resources, the addition of another platform to the nation's research facilities will require a compelling argument. A clear case must be made for what these platforms will provide that is not now available. A sufficiently large user community with the ability to generate funding is essential. Consortiums and partnerships will necessarily be part of the solution. Lastly, leasing a ship for some period(s) of time is likely a more attractive option-logistically and financially-than a direct govemment/agency funded purchase.

For aerostats, costs are less formidable. However, a shared-use facility is still an attractive option. In this way, equipment is more fully utilized, project costs reduced, and expertise shared.

VI. A PATH FORWARD TO A NATIONAL FACILITY

In September of 2000, the utility of airships and aerostats has been convincingly demonstrated, and several projects have yielded published results. The concept of a multi- agency, multi-investigator airship, based on the UNOLS or UCAR models, has been discussed in several national forums [14,15,16]. Likewise, one or more aerostats could appropriately become multi-user facilities. Marine mammal research and habitat monitoring would be one of the foremost uses, although, as described above, applications are widespread. In many fields, recent incorporation of new technologies have allowed significant advances in our observational capabilities [ 171. Lighter-than-air platforms may provide new and better ways of looking at the ocean, sea/air interface, and the lower atmosphere.

REFERENCES

[I] J.H.W. Hain. 1992. Airships for marine mammal research: Evaluation and recommendations. Publication No. PB92-128271. National Technical Information Service, Springfield, VA. 34 pp.

[2] J.H.W. Hain, S.L. Ellis, R.D. Kenney, B.K. Gray, PI . Clapham, M.T. Weinrich, and 1.G. Babb. 1995. Apparent bottom feeding by humpback whales on Stellwagen Bank. Mar. Mamm. Sci. 11: 464-479.

[3] J.H.W. Hain, S.L. Ellis, R.D. Kenney, and C.K. Slay. 1999. Sightability of right whales in coastal waters of the southeastern United States with implications for the aerial monitoring program. Pp. 191-207, In, Murine Mummul Survey and Assessment Methods, G.W. Garner, S.C. Amsmp J.L. Laake, B.F.J. Manley, L.L. McDonald, and D.G. Robertson (eds). A.A. Balkema: Rotterdam, Netherlands.

[4] T.V. Blanc, W.C. Keller, and W. J. Plant. 1989. Oceanography from a blimp. Sea Technology 3 0 23-28.

[5] W.J. Plant, W.C. Keller, V. Hesany, and K. Hayes. 1998. Measurements of the marine boundary layer from an airship. J . Atmos. Ocean. Tech. 15: 1433-1458.

[6] Plant, W.J., D.E. Weismann, W.C. Keller, V. Hesany, K. Hayes, and K.W. Hoppel. 1999. Aidsea momentum transfer and microwave cross sectionofthesea. J.Geophys. Res. 104: 11173-11191.

[7] G.A. Frick and W.A. Hoppel. 1993. Airship measurements of aerosol size distributions, cloud droplet spectra, and trace gas concentrations in the marine boundary layer. Bull. Am. Meteor. Soc. 74: 2195-2202.

[8] W.A. Hoppel, G.M. Frick, and J.W. Firgerald. 1994. Marine boundary layer measurements of new particle formation and the effects nonprecipitating clouds have on aerosol size distribution. J . Geophysical Res. 99: 14443-14459.

[U] Aerospace Corporation, El Segundo, CA. 1999. Personal communication.

[IO] Anonymous. 2000. Mineseeker announced. Airship 128: 3-5.

[ I 1) K. Riitzler. 1978. Photogrammetry of reef environments by helium balloon. Coral reefs: Research methods. D.R. Stoddart and R.E. Johannes, eds. Monographs on Oceanogruphic Methodology 5 : 45-52. [I21 R.O. Flamm, E.C.G. Owen, C.F.W. Owen, R.S. Wells, and D. Nowacek. 2000. Aerial videogrammetry from a tethered airship to assess manatee life-stage structure. Mar. Man" Sci. 16: 617-630.

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[I31 R.D. Clark. 2000. Measurements of PM,,, O,, and meteorological [IS] NOAA. 1993. NOAA's Aircraft Modemization Study: Final Report of variables obtained using tethered balloons during the NARSTO-NE-OPS the NOAA Study Committee, March 1993. DOC/NOAA: Washington, D.C. pilot study. Pp. 6-7, In, Proceedings of PM2000: Particulate Matter and Heolih, 24-28 January 2000, Charleston, SC. [I61 UNOLS. 1994. Coastal oceanography: Future trends and vessel

requirements. A status report by the Coastal Oceanography Subcommittee of [I41 J.H.W. Hain. 1999. Update on application of airships and aerostats to the UNOLS Fleet Improvement Committee. UNOLS FIC Report. 32 pp. whale and habitat research. Document No. AlAA 99-3902, 13Ih AIAA Lighter-Than-Air Systems Technology Conference, 28-30 June 19Y9. [ I71 H.L. Clark. 1993. Instrumentation opportunities for ocean science Norfolk, VA. American Institute of Aeronautics and Astronautics, Reston, VA. 6pp.

research. Sea Technology 34: 10-1 3.

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