Frequently Asked Questions
- SeaWiFS (Sea-viewing Wide Field-of-view Sensor), the first ocean color satellite that permitted continuous remote observation of plant life in the ocean (operational from 1997-2010). But the "ocean color story" goes a little further back, with the launch of CZCS (Coastal Zone Color Scanner), which was the first satellite that collected - not continuously - ocean color data (1978-1986). It's really cool that there are people in our lab who were part of that mission - they had printouts and punchcards! Things work a little bit differently these days. Data is delivered automatically, within a couple of hours.Source: Dr. Ivona Cetinić, Ocean Ecologist, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.
- This is a very complicated question, and is explained in more detail in reports by the Intergovernmental Panel on Climate Change (IPCC) and others. However, as a basic overview, as light from the sun enters the earth's atmosphere, aerosols scatter the Sun's light, which results in a local cooling effect. However, some aerosols also absorb light, which can result in a local warming effect, depending on the amount of aerosols, their altitude, and the brightness of the underlying (Earth's) surface at the place in question. The net direct effect of this scattering and absorption is by aerosols is cooling, when averaged across the globe. This means that aerosols have offset part of the positive forcing (warming) due to greenhouse gases such as carbon dioxide (CO2). However because the lifetimes of aerosols in the atmosphere are very short compared to greenhouse gases, and because aerosols vary a lot over time and from place-to-place, it is not correct to say that aerosols cancel out the effects of greenhouse gases. Additionally, aerosols can have complex influences on cloud formation and evolution, which further modify the Earth's energy balance.Source: PACE Aerosol & Cloud Scientists.
- Aerosols are small particles suspended in the atmosphere. Some are natural and some are human-derived. Examples are smoke from fires, dust from deserts, volcanic ash from eruptions, and urban haze from industrial activities. We are interested in them for reasons including climate change, health and air quality, hazard monitoring, ecology, and more.
Learn More about AerosolsSource: PACE Aerosol & Cloud Scientists.
- Yes and no. The dictionary definition of aerosols applies to both - small particles suspended in a gas. While the contents of some spray cans could contribute to your home's "aerosol conditions" at times, spray cans are not considered to be a big source of the aerosols that we study in the earth's atmosphere.Source: PACE Aerosol & Cloud Scientists.
- We typically study aerosols using data collected by instruments mounted on Earth-looking space satellites. These instruments record the amount of sunlight reflected from the Earth's surface and from the atmosphere. As aerosols scatter and absorb the sun's radiation, they affect the brightness and color of these images. We can use information from multiple colors of lights (wavelengths), and sometimes measurements taken from different angles and/or polarization states of light, to determine the characteristics of aerosols and underlying surface in the scene.Source: PACE Aerosol & Cloud Scientists.
- Clouds are formed when water in the atmosphere condenses. Dependent on factors such as the temperature, they may be formed of liquid water droplets, ice crystals, or a mixture of both.Source: PACE Aerosol & Cloud Scientists.
- Monitoring Earth's cloudiness from space is useful for many reasons. Two of the most important are for providing input to weather forecasts, and for climate monitoring purposes. Clouds reflect the Sun's visible light and can trap the Earth's emitted thermal radiation, so changing cover and properties of cloud can affect the Earth's energy balance.Source: PACE Aerosol & Cloud Scientists.
- We typically measure clouds from space using measurements of reflected Sunlight observed by satellites. We think of clouds as bright and white, but by measuring the brightness at multiple colors (wavelengths) of light, we can say something about how much water is in the cloud, how big its droplets are, how high in the atmosphere it is, and whether it is made of liquid water droplets or ice crystals.Source: PACE Aerosol & Cloud Scientists.
- Yes, phytoplankton do have chlorophyll (light-absorbing green pigment within plants), but they also have other pigments that influence how they absorb and scatter light. These other pigments are called accessory pigments. They allow the phytoplankton to efficiently absorb more light, but of different colors (wavelengths) than if they had just chlorophyll pigment. So depending on how much each of these pigments they have, they can override the chlorophyll and actually make them a different color. Also, not only is the pigment content of the phytoplankton important, but also the size and shape. So the way that the light is scattered by the texture, size, and shape of that phytoplankton will also influence the color. So, they're not always green.
- First, if you work with satellite data, you're drier, and you don't get seasick! We do need the ship-based research to ground truth the satellite data. If you think about it from an ocean scientist perspective, it's just two different tools in your tool set. We can go to sea and collect information directly that allows us to develop algorithms - mathematical relationships - that ultimately connect the ocean color measurements that we sense remotely from space with the things that we want to measure in the ocean - for instance, the number and type of phytoplankton in the seawater. But then there are days when we're stuck in front of the computer and dream about the sea, and then we go to sea and dream about being dry and stuck in front of the computer.
Satellite data show us greater coverage geographically of the ocean surface. When we're on a ship, we're only hitting this (tiny) part of the ocean, but the satellite is covering the entire ocean. So ultimately, we get a lot more information from satellites, versus just data from one portion of the ocean when we're sampling on a ship.Source: Dr. Ivona Cetinić, Ocean Ecologist and Aimee Neeley, Oceanographer, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.
- some studies that have looked at the iron input from those Saharan dust storms into the Gulf of Mexico and the middle of the Atlantic that might actually stimulate things like Trichodesmium (a type of cyanobacterium that likes iron). So that iron that comes from the Saharan Desert will actually stimulate them to grow. So yes, it can have an impact on phytoplankton.
- sawdust on the (ocean) surface and you can see that with the naked eye. Another dinoflagellate, Karenia brevis - if there's enough of it in a bottle - you can see the little balls swimming around. They're about the size of Alexandrium, which you can almost see with the naked eye.
- I grow my own monocultures (= one species only) of various types of phytoplankton in one of our labs here at Goddard. Basically, every two to three weeks, I make fresh growth mediums (dissolved vitamins, minerals, and nutrients - all they need to survive - mixed in with seawater), and I transfer the phytplankton cultures to the new medium. After a while the cells use up all the nutrients and starts to die, just like in the ocean, so you have to replenish their nutrients. So every few weeks I have to put them in new seawater with nutrients. So far they haven't needed any waves to survive in stationary flasks.
There are places where you can buy starter cultures and grow them yourself. I did see an advertisement for bioluminescent phytoplankton (organisms that produce their own light). Otherwise, when scientists collect phytoplankton to make into a monoculture, they have to go out to sea and individually isolate different cells and then start growing them.
- more abundant blooms in the coastal ocean, especially harmful algal blooms (plankton blooms that have the capacity to cause physical injury, or other negative outcomes, when they reproduce quickly and have high concentrations in seawater).
- Oh, that's a great question. There are many tests we want to do. The first type of tests are called performance testing. These tests make sure the instrument can gather the right amount of data, with the right calibration and the error bands that we want. So, one way we do that is we use a laser. We have a system called GLAMR (Goddard Laser for Absolute Measure of Radiance) that is a tunable laser and that allows us to tune the wavelength of light that goes into the instrument. This makes us sure that the instrument can measure those particular wavelengths. So we use those types of performance tests to make sure the instrument can collect the light that we want. So that's one type of testing.
Another type of testing we do is to make sure that the instrument can survive the rigors of launch and the space environment. So for those types of tests we will do a vibration test where we shake the instrument to make sure it stays together and doesn't fall apart during launch. We will also do thermal tests where we make the instrument very hot and then very cold and very hot and very cold to simulate the space environment as we orbit the earth to make sure it can survive.
So, in a nutshell, there are many tests I could go into, but we do performance tests and environmental tests.
- Yes, we do look at inland water bodies so long as those water bodies are big enough that the satellite footprint is only looking at water vs. a mixture of water and land. And I think off the top of my head there are on the order of 150 to 200 lakes inside of the continental United States that are resolvable from an instrument like PACE.
- Red tides are one example of a harmful algal bloom and they are responsible for contaminating shell fisheries, and closing beaches, and fish kills. So, of course they're very very critical to getting a handle on. It's not always possible to visit the shore when you think these might happen. The satellites play an incredibly important role in identifying where these occur, when they're happening, and the duration of their occurrence so that this information can feed back into management decisions and watershed activities try to prevent a future occurrence of this. So the answer to your question is yes.
- I don't know the exact number because the team is very large. I would say on the Instrument Team, we probably have roughly 200 people working on OCI. And then, on the Spacecraft Team, with all of the different spacecraft subsystems, we probably have another 100 or 150 all told working on it. And that's just the folks at Goddard Space Flight Center. In addition to the folks who are working here at NASA Goddard, we also have industry partners and university partners all across the country and all across the globe who are supplying different components and different instruments for the PACE mission. So, it does take a lot of people to make a space mission like this come together and it's really the combined efforts and craftsmanship of many people across the whole world to make this happen.
- PACE will not be collecting data on the dark side of the earth so it will not be collecting data at night.
- PACE is going to launch towards the end of 2022. We don't have an exact launch date set and it will launch from either an Atlas 5 rocket or a Falcon 9 rocket. We have a competitive procurement that will go out for those vehicles through our partners at Kennedy Space Center. They arrange our launch services. And it will launch from Vandenberg Air Force Base in California. That launch site allows us to fly over water and it's a good polar orbit so we do have to launch from Vandenberg.