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Frequently Asked Questions

      • An aerial view of the Kennedy Space Center Launch Complex 39 area, showing the Vehicle Assembly Building (center) with the Launch Control Center at right.
        Credit: NASA.
        Kennedy Space Center (KSC) on Cape Canaveral, Florida, USA
      • We plan to launch on 6 February 2024. This date could slip by a day or more because of weather or to 8 February 2024 for technical reasons at Kennedy Space Center.
      • NASA’s 22nd SpaceX cargo resupply mission launched in June 2021.
        Credit: NASA TV.
        A SpaceX Falcon 9, whose first stage booster will have been used 3 previous times. SpaceX plans to recover the first stage as part of the process of PACE's launch.
      • The spacecraft will separate from the launch vehicle roughly 13 minutes after launch. We expect first communication with the spacecraft, however, after roughly 5 minutes.
      • The term "ocean color" refers to the spectral composition of the visible light field that emanates from the ocean. The color of the ocean depends on the solar irradiance spectrum, atmospheric conditions, solar and viewing geometries, and the absorption and scattering properties of water and the substances that are dissolved and suspended in the water column, for example, phytoplankton and suspended sediments.
        Source: Werdell, P.J. and McClain, C.R. (2019), Satellite Remote Sensing: Ocean Color, Encyclopedia of Ocean Sciences, 3rd Edition, 443-455.
      • Twenty years of global biosphere
        This data visualization shows the Earth’s biosphere from September 1997 through September 2017. Credit: NASA/GSFC.
        This visualization shows ocean color data collected by 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.

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      • 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 (wavelengths of light) of these observations. We can use information from multiple colors of wavelengths, and measurements taken from different angles and/or polarization states of light, to determine the characteristics of aerosols and what at is happening on the land/ocean below.
        Source: PACE Aerosol & Cloud Scientists.

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      • 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 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.
      • Clouds are formed when water vapor 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.

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      • 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 Earth's emitted thermal radiation, so changing the cover and properties of clouds can affect the Earth's energy balance.
        Source: PACE Aerosol & Cloud Scientists.

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      • 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 of these pigments they each 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.
        Source: Aimee Neeley, Oceanographer, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.

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      • Karen brevis, magnified 20x
        Karen brevis, magnified 20x..
        There are. Trichodesmium forms little strands and group together to form colonies (1-10 mm in length). And when you're out at sea - and we've both seen this ourselves - they actually form what we call sawdust on the (ocean) surface and you can see that with the naked eye. Another dinoflagellate, Karenia braves - if there's a high enough concentration of it in a bottle - you can see the little balls swimming around. They're about the size of Alexandrium (another dinoflagellate, 0.018 - 0.045 mm) which you can almost see with the naked eye.
        Source: Aimee Neeley, Oceanographer, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.

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      • 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 phytoplankton cultures to the new medium. After a while the cells use up all the nutrients and start 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.
        Source: Aimee Neeley, Oceanographer, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.

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      • 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.
      • Phytoplankton and blue-green algae blooms in the Baltic Sea
        Phytoplankton and blue-green algae blooms in the Baltic Sea (July 23, 2018). More frequent and massive blooms, combined with warming seas due to climate change, are making it harder for fish and other marine life to thrive in this basin. Credit: NASA Earth Observatory.
        There are many studies looking at the impact of climate change on the oceans, and ultimately on ocean life. Many of them are looking at the impact climate change has on phytoplankton diversity and abundance. Scientists have seen over the last few years changes in the way that the land interacts with the ocean - increases in land-based input through rivers, and processes associated with agriculture, and so on - which we see results in 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).
        Source: Dr. Ivona Cetinić, Ocean Ecologist, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.

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      • Twenty years of global biosphere
        This data visualization shows a global representation of Earth’s plant life both in the ocean and on land from September 1997 through September 2017. Credit: NASA/GSFC.
        Yes, and in fact that was one of the original reasons for developing ocean color from space technology. When you look at a place - again, going back to this visualization one more time, which if you couldn't tell is pretty much my absolute favorite - look in the northern (Atlantic) ocean between the United States and Europe, and you'll notice there that there are a lot of those rich reds and yellows that I was talking about that appear and disappear (over time). So again, we're looking for phytoplankton, and we're looking for what effectively is "fish food" in a way. Phytoplankton are eaten by bigger plankton that are then eaten by fish, and the chain of life continues. By using satellite imagery to see where there's a lot of this algal biomass in our water bodies, we are effectively able to make predictions about where successful fishing might occur.
        Source: Dr. Jeremy Werdell, PACE Project Scientist, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.

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      • PACE is currently scheduled to launch in January 2024 (moved from the previous target of December 2022).

        NASA has selected SpaceX of Hawthorne, California, to provide launch services for the mission. It is currently is targeted to launch on a Falcon 9 Full Thrust rocket from Cape Canaveral Air Force Station in Florida. NASA's Launch Services Program at the agency's Kennedy Space Center in Florida will manage the SpaceX launch service.
        Source: NASA Awards Launch Services Contract for Earth Science Mission (Feb 2020 Press Release) .

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      • Yes. The NASA data we are providing are free and open to the public (generally non-commercial use) but we would love to see these data. It would be incredibly rewarding to see these data used in the classroom. And beyond that, NASA Goddard Space Flight Center also provides software and visualization tools that are open source to the public that will aid in using these data intuitively. [They are] easy so the learning curve for bringing this into the classroom should be super seamless. The data will be available in one place and the software are available in the exact same place. And thank you in advance for using it in your classroom - that's fantastic!
        Source: Dr. Jeremy Werdell, PACE Project Scientist, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.
      • 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.
        Source: Dr. Gary Davis, PACE Mission Systems Engineer, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.

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      • 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.
        Source: Dr. Gary Davis, PACE Mission Systems Engineer, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.
      • Yes, we do look at inland water bodies so long as those water bodies are big enough that the satellite footprint (1 km2 or 0.4 mi2) 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.
        Source: Dr. Jeremy Werdell, PACE Project Scientist, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.
      • Red tides are one example of a harmful algal bloom and they are responsible for contaminating shell fisheries, 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 to try and prevent a future occurrence of this. So the answer to your question is yes.
        Source: Dr. Jeremy Werdell, PACE Project Scientist, NASA Goddard Space Flight Center in Beyond Blue: Why Ocean Color Really Matters.

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