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Ask an Expert: Tracking Sickness From Space
The blacklegged tick, shown here, is known as one of the disease transmitting organisms for Lyme disease. NASA technology helps track tick habitats to control Lyme disease. Credit: CDC
Scanning electron microscope image of prairie hollyhock pollen A false-color electron microscope scan shows a prickly grain of prairie hollyhock pollen. Credit: Dartmouth College/Charles Daghlian
Urban heat island image of Atlanta, Georgia in 1997 An urban heat island image of Atlanta, aptly named "Hot-lanta." Credit: NASA

More Information
Video: Ticks From Space!
Feature: Satellites Check for...Ticks?
Photos: Ticks and Lyme Disease
Feature: Tracking Allergies From Space
Feature: Satellites Track Strokes
Fact Sheet: NASA's 'Heat Hunters'
Sometimes the best way to fight sickness on Earth starts with a view from space...

On Thursday, June 10, Dr. Jeff Luvall, a research scientist at NASA's Marshall Space Flight Center, answered your questions about "Tracking Sickness from Space." NASA research has been "instrumental" in tracking conditions that affect health on Earth, including allergies, heat-related illnesses, Lyme disease, and heart and stroke conditions.

More About Chat Expert Jeff Luvall

Dr. Jeff Luvall, a research scientist at NASA's Marshall Space Flight Center, will be answering your questions about "Tracking Sickness from Space." Luvall has been involved with tracking a variety of health-related conditions using NASA resources -- primarily satellite imagery and data and aircraft studying atmospheric and climate conditions.

To date, Luvall has studied allergy-related conditions by tracking pollen, and documented and provided mitigation solutions for "urban heat islands," which occur when trapped heat builds up during the day in buildings, pavement and other urban surfaces, contributing to heat-related health issues. Additionally, Luvall has trained students and professionals to use NASA satellite data in improving medicine and contributing to public health.

One of his main areas of study for the last three years has been working with students researching Lyme and West Nile diseases. The populations of the vectors for these diseases (mosquitoes, ticks) are dependent on both habitat and environmental conditions that vary both in time and space, making them ideal to study using NASA based satellite technology.

Chat Transcript

(Moderator) Jason: Hello and welcome to this chat. Please go ahead and start asking your questions. We're begining to answer those you've already submitted. To submit your own question, please type in in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks!

enoch: Is the satellite used for tracking the sick people is a infraed sensor satellite?

Jeff: Hi enoch. The resolution on satellites isn't good enough to track people. We use satellite thermal images to look at environmental conditions.

enoch: If so how do u differentiate body teperatures of different things on earth?

Jeff: The Earth re-radiates the energy absorbed by the sun in the thermal wavelenghts Each object will have a different temperature under similar environmental conditions. For example, asphalt parking lots will be much warmer than lawns.

byrdk50: What are some current devices that are in space now to help?

Jeff: NASA has many satellites that observe the Earth's surface. Some like LANDSAT series have been observing the Earth's surface for over 30 years. Other satellites have only been in orbit for 5-10 years. Each satellite is tasked with different observational capabilities.

enoch: So if there are a thousand types of thermal variations on the earth, how do u identify people?

Jeff(A) We don't. :) But we do identify environmental conditions that affect people.

Tavish_DeGroot: How sceptically received was the idea that you could track allergies from a space satellite?

Jeff: We're not directly tracking "allergies" from space. We can track dust clouds and observe phenology of plants which produce the pollen that causes allergies.

Akarsh: Answer my questions about space sickness!

Jeff: Hi akarsh. We're actually talking about environemental public health, rather than "space sickness." We appreciate your questions.

jjordan10: How do you track tick habitats?

Jeff: Ticks require heavily vegetated areas and a high level of soil moisture. We can map vegetation that matches those criteria using satellite data.

dallasdm: How is the information from satellites used to track heart dsease? Can you give a specific example?

Jeff: Well, we don't directly track heart disease, however, we can use the satellite data to map environmental conditions that may contribute to heat stress or other health problems.

enoch: The topic is about tracking sickness! How does tracking dust clouds have do anything with the sickness of people?

Jeff: Because dust particles in themselves are very irritating to the respiratory system. In addition, dust particles are made up of fragments of bacteria cell walls which, if inhaled, can cause the body's immune system to react.

Akarsh: Thank you.

Jeff: You're welcome!

Tavish_DeGroot: How do you differentiate pollen clouds from other types of dust clouds?

Jeff: We can't directly observe pollen clouds from satellites like we do dust clouds because the pollen particles are much larger and aren't observable using the wavelengths on the current satellites. We do observe the vegetation and can identify when the vegetation is producing pollen, particularly with juniper forests in the Southwestern United States.

cdolling: So how helpful is the ability to track from space and how does it improve knowledge/science?

Jeff: One of the problems with pollen counts is that they are done very infrequently, and there aren't many pollen counting stations throughout the U.S. So there's a real lack of data for pollen counts. It's very hard to predict the timing of pollen release and its transport without using satellite data and models. Our goal is to provide a heads-up alert to the public health community so that doctors can begin treating their patients and coordinating emergency room staffing.

hsd123: So you find an area via a satellite that matches the criteria for heavy tick infiltration; then do you notify the CDC or another organization to let them know to be on the lookout for Lime or West Nile? Is that how it works?

Jeff: No, we're not that sophisticated yet. :) Just because there is a large tick population doesn't mean the ticks are infected with Lyme disease.

spacecadet: How does tracking allergens benefit people?

Jeff: Because allergies can cause debilitating and fatal reactions in some people and make others very uncomfortable.

Karen: Your work is fascinating. Do you recommend classroom activities or is there an existing educator guide for helping teachers bring your research into the classroom?

Jeff: Yes, you can contact Janet Anderson -- her contact information is at the bottom of this page. She'll provide that information via Web links.

Jason: Keep the excellent questions coming. To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

Akarsh: Sir, can Ultaviolet cause health problems? Is NASA introducing any new methods to control UltraViolet Rays?

Jeff: We can't control UV -- the only way to reduce risk is to reduce exposure.

enoch: But if the body's immune system is already been affected by a sickness then the reaction given by the immune system will vary !!am i right?

Jeff: People's reaction to pollen can be particularly severe if they have a compromised immune system. The bacteria fragments contained on dust can cause very severe medical problems. So yes, you are right. :)

jjordan10: What types of heat related conditions are caused by urban heat islands?

Jeff: The process of urbanization across the landscape produces an increase in air temperature within the city of several degrees. Also, night-time temps don't drop so particularly the elderly don't get relief at night, causing them a lot of stress.

Tavish_DeGroot: How does the relationship between NASA and health researchers work? Did the researchers request data, or did NASA offer it?

Jeff: NASA researchers work in cooperation with other researchers from universities and private sectors. They produce joint proposals to work together in areas of mutual interest. These proposals are in response to NASA's call for proposals.

dallasdm: Does any satellites have the ability to identify bacteria or other organic substances besides pollen that might be health risks in dust clouds or other environmental conditions?

Jeff: Typically we can look at air quality particles like PM2.5 and ozone, using satellite data.

byrdk50: How can you track Strokes?

Jeff: We have a program called REGARDS that tracks environmental conditions that are related to strokes. It's a study being conducted at UAB, the University of Alabama in Birmingham.

Tavish_DeGroot: How hard was it to prove, or at least have good basis for, the relationship between the observed characteristics of the juniper forests, and their pollen production?

Jeff: We're able to see a signal from the juniper communities that indicates the formation of pollen. This signal is very small and requires very careful instrument calibration and removal of atmospheric affects in order to observe it.

enoch: can u identify heat sickness then?

Jeff: In a manner of speaking. We can map areas using thermal satellite images that indicate a potential for heat stress.

Akarsh: How do Thermal Images help to look environment conditions?

Jeff: The surface temperature tells us a lot about what is happening at the surface. It helps us understand if the vegetation is well-watered, it tells us if the vegetation is under water stress, and allows us to determine the surface air temperature.

radio_mike: How does what you track vary from urban to rural areas?

Jeff: Typically you'll see the large dust plumes in rural areas because of agriculture, or in the Southwestern areas with sparse vegetation. We don't see the dust clouds in urban areas because there's not a large source area.

(moderator) Jason: We're working to get through all of the great questions you've asked us. Keep them coming! To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

01cj: How can you track mosquito population from space?

Jeff: Unfortunately, we can't track this from space. But we CAN map their habitats.

Akarsh: Sir, are pollen clouds the only clouds which cant be seen with naked eye? Is there any another?

Jeff: The EPA PM2.5 pollutant scale can't be seen with the naked eye.

Tavish_DeGroot: Is it kind of ironic that satellite observation to predict pollen production is being investigated because there are few pollen counting stations, but pollen counts are needing to be done to prove the models used in pollen production predictions? :)

Jeff: Yes, that's a real problem in trying to make the linkage!

hsd123: With the constant growth of urban development, aren't there going to be fewer and fewer areas of heavy vegitation -- which I guess would mean an upswing in temperatures from asphalt and such, which would cause other issues instead...maybe?

Jeff: Urban heat islands are a real concern. However, many commnunities have realized the necessity and value of green space as part of their urban planning process. Also, their has been much research on providing lighter-colored asphalt and concrete to reduce their heating.

Tavish_DeGroot: What is the strength of the corrolations between the satellite observed conditions, and the monitered health conditions that you're studying?

Jeff: We're still working on that!

Tavish_DeGroot: Was there a specific reason that juniper forests were picked out to be observed for pollen production?

Jeff: Juniper forests are the easiest to study because they occur throughout the Southwest, Texas, and Oklahoma and form simple forest communities that are consistent with our ability to observe them from space.

jjordan10: What other types of allergens do you track?

Jeff: Pollen and dust are the two main ones.

spacecadet: So what do you do with the information you collect?

Jeff: We organize the data so that it's useful to the public health community. The CDC (Center for Disease Control) has an environmental tracking network web page. We'll provide the link after this chat. (

jweddend: Is it true that the city of Phoenix is such a heat island that it doesn't rain in the city?

Jeff: We've found in studying urban heat islands that the rainfall patterns are altered in some areas the timing of the rainfall is shifted to later in the day or early morning. And, the rainfall occurs downwind from the city, making the city drier. In other areas there are more storms over the city.

Tavish_DeGroot: Would there be a use for a satellite built with specific sensors for monitering health-related enviromental conditions, or is the required data already provided by satellites performing other observations?

Jeff: We'd like to have a dedicated satellite for addressing public health research. The current satellites aren't optimal in temporal or spatial resolution to address many of our public health concerns. Also, there needs to be more thermal imagery available.

dallasdm: What is PM2.5?

Jeff: It's particulate matter below 2.5 microns in size. At that size, particles bypass the body's natural filtering system and are drawn deep into the lungs.

Akarsh: Sir, can you explain more about REGARDS program?

Jeff: We'll provide more links on this page after the chat.

cdolling: Where can you see this going in future? What are the possibilities that can come from this knowledge?

Jeff: I'd like to see integrated end-to-end system where NASA provides satellite imagery and modeling directly into the decision support system of the public health community, and enhance the capability to serve humans.

abishek: Sir can you track h1n1viruses through what devices has nasa set up to track it?

Jeff: No, this isn't something that we track.

Akarsh: From were do we get Thermal Satellite Images?

Jeff: There are several satellites such as AVHRR, ASTER, LANDSAT, GOES, and MODIS which provide thermal data. However, the spatial resolution isn't optimal for public health research.

Tavish_DeGroot: How far away, do you think, are pollen and/or heat stress warnings on the news along with the weather segment? :)

Jeff: I'd hope to see this in the next five years or so. Already we're seeing NASA satellite data and models being used on The Weather Channel.

john: Thermal imahes would just be bcoz of some earth heat (volcona/fire/after fire/ climate) how can we say anything about sickness based on thermal heat?

Jeff: We can easily ID volcanos and forest fires with shortwave IFR channels on the satellites. Those temps, of course, are much higher than the environmental temps we measure with thermal IFR. We use the thermal data to determine the habitat envrironmental conditions such as soil moisture, air temp, and relative humidity.

Tavish_DeGroot: One of the features said that standing water was tracked. How small a body of water can be detected?

Jeff: Depending on the satellite resolution, water bodies can easily be seen with satellite data. The best resolution is about 1/2 meter so water bodies 2-3 meters across can be seen.

spacecadet: Can you track any type of cancer?

Jeff: No, we can't.

enoch: I already asked mine can u track viral diseases or viruses itself?

Jeff: No, we only measure environmental conditions, not the virus or bacteria itself.

abishek: Sir can growing trees hep reducing heat stress?

Jeff: Yes, by shading your house and parking lots!

jjordan10: How many satilites are used in tracking tick and mosquito habitats?

Jeff: We primarily use two satellites: ASTER and MODIS.

dallasdm: If a satellite sees an increase in PM2.5 in a particular area, would it notify ground-based health organizations with more sensitive air quality equipment so that these can be identified as to their health risk?

Jeff: Yes, we're working on that right now.

Akarsh: What is Bulls-Eye Rash?

Jeff: That's a major symptom of initial Lyme's disease infection.

(Moderator) Jason: We're still working on answering all the great questions you've asked. If you haven't seen yours yet, give us a few minutes to get to all of your questions. To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

abishek: Can you give some disease transmitting organisms of lyme disease?

Jeff: Ticks. :)

JAGS: Very informative chat room.. A technology that would greatly help 3rd world countries.

Jeff: Yes, very true. We're working closely with other countries to utilize this technology.

abishek: Sir thanks a lots.

Jeff: You're very welcome.

Tavish_DeGroot: In observing bodies of water, how do you tell standing water apart from partially-obscured small streams or creeks?

Jeff: One way is by temperature. However, unless you have thermal data collected from aircraft, the current generation of satellites don't provide good enough spatial resolution to do so.

Akarsh: Can we track all types of Lyme diseases?

Jeff: We don't really track Lyme disease -- we track tick habitats.

Akarsh: What is the symtoms of Bulls Eye Rash?

Jeff: A great link for this is They have a wealth of information.

Tavish_DeGroot: Thanks for the informative chat! Cheers, mate! :)

Jeff: My pleasure -- thanks for the great questions.

enoch: Does NASA use the passive infrared sensor satellites too?

Jeff: They're all passive. :)

rs16aries: What diseases apart from allergies and pollen u can track?

Jeff: We track mosquito habitats to help control malaria and dengue.

01cj: Thank you i appreciate you doing this.

Jeff: I appreciate your questions.

01cj: When will you be doing this again?

Jeff: We'll be having another chat next Thursday (June 17) to discuss solar flares, etc. with NASA scientist David Hathaway.

abishek: Can "Hot-lanta" try this method of growing trees?

Jeff: They are! They're one of our first urban heat island studies and have been proactive in planting trees via Trees Atlanta.

Akarsh: Sir what are the preventive measures for Lyme Disease?

Jeff(A) Again, the CDC web site at is a great resource.

Akarsh: Dir can you explain ASTER AND MODIS?

Jeff: ASTER is Advnaced Spaceborne Thermal Emission and Reflection Radiometer. MODIS is Moderate Resolution Imaging Spectroradiometer.

01cj: How do you map mosquitos habitats?

Jeff: By mapping bodies of standing water and vegetation interfaces.

Akarsh: Sir, what do you do at NASA? What is your native place?

Jeff: I'm at Marshall Space Flight Center and I'm a forest ecologist by training.

01cj: After the satilites collect the data on pollen and dust where does it get sent?

Jeff: We are working closely with the CDC and public health departments to provide information to their Web sites. This will happen later in the project within the next couple of years.

dallasdm: Fascinating! I learned a lot.

Jeff: Great -- thanks for participating in the chat!

Akarsh: Sir I know the full form of ASTER AND MODI but i want detail about that?

Jeff: You can learn more at these links: and

enoch: What is a spectroradiameter?

Jeff: It measures energy at many wavelengths.

Akarsh: How do Ticks carry poison? :-)

Jeff: They don't, not exactly. Lyme disease is a bacterium.

abishek: Hope you have a good time with us sir thanks a very lot.

Jeff: I did -- thanks for being here in the chat.

jjordan10: How long has this project been going on?

Jeff: About a year for the pollen project.

01cj: Do you like doing this?

Jeff: I do. I like good questions!

Akarsh: Sir are people from the world allowed to chat?

Jeff: Anyone with an Internet connection can join in and ask their questions.

01cj: You have been a great help thank you. you are very smart.

Jeff: Thanks -- that's NOT what my teen-aged kids say. :)

jjordan10: Thanks for the great answers.

Jeff: You're welcome. Thanks for the great questions.

01cj: Will you do this any more?

Jeff: I'd be happy to come back!

(Moderator) Jason: Thanks to all of you for the great questions, and thanks to our guest scientist, Jeff Luvall! Check back in the next day or two for a posted transcript of today’s chat. Have a great afternoon.

Janet Anderson, 256-544-0034
Marshall Space Flight Center, Huntsville, Ala.