Deep Space Climate Observatory

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Deep Space Climate Observatory
DSCOVR spacecraft model.png
Artist's rendering of DSCOVR
NamesTriana
Mission typeSolar observation
OperatorNASA / NOAA
COSPAR ID2015-007A
SATCAT no.40390
Websitewww.nesdis.noaa.gov/dscovr
Mission durationPlanned: 5 years[1]
Elapsed: 4 years, 10 months
Spacecraft properties
Launch mass570 kg (1,257 lb)[2]
DimensionsUndeployed: 1.4 × 1.8 m (54 × 72 in)[2]
Power600 W
Start of mission
Launch dateFebruary 11, 2015, 23:03:02 (2015-02-11UTC23:03:02Z) UTC
RocketFalcon 9 v1.1
Launch siteCape Canaveral SLC-40
ContractorSpaceX
Orbital parameters
Reference systemHeliocentric
RegimeL1 point[1]
DSCOVR Logo (transparent bg).png  

Deep Space Climate Observatory (DSCOVR; formerly known as Triana, unofficially known as GoreSat[3]) is a NOAA space weather, space climate, and Earth observation satellite. It was launched by SpaceX on a Falcon 9 launch vehicle on February 11, 2015, from Cape Canaveral.[4] This is NOAA's first operational deep space satellite and became its primary system of warning Earth in the event of solar magnetic storms.[5]

DSCOVR was originally proposed as an Earth observation spacecraft positioned at the Sun–Earth L1 Lagrangian point, providing live video of the sunlit side of the planet through the Internet as well as science instruments to study climate change. Political changes in the United States resulted in the mission's cancellation, and in 2001 the spacecraft was placed into storage.

Proponents of the mission continued to push for its reinstatement, and a change in presidential administration in 2009 resulted in DSCOVR being taken out of storage and refurbished, and its mission was refocused to solar observation and early warning of coronal mass ejections while still providing Earth observation and climate monitoring. It launched aboard a SpaceX Falcon 9 rocket on February 11, 2015, and reached L1 on June 8, 2015.

NOAA operates DSCOVR from its Satellite Operations Facility in Suitland, Maryland. The acquired space data that allows for accurate weather forecasts are carried out in the Space Weather Prediction Center in Boulder, Colorado. Archival records are held by the National Centers for Environmental Information, and processing of Earth sensor data is carried out by NASA.[1]

History[edit]

Deep Space Climate Observatory

DSCOVR began as a proposal in 1998 by then-Vice President Al Gore for the purpose of whole-Earth observation at the Sun–Earth L1 Lagrangian point, 1.5 million km (930 thousand mi) from Earth.[3][6] Originally known as Triana, named after Rodrigo de Triana, the first of Columbus's crew to sight land in the Americas, the spacecraft's original purpose was to provide a near-continuous view of the entire Earth and make that live image available via the Internet. Gore hoped not only to advance science with these images, but also to raise awareness of the Earth itself, updating the influential Blue Marble photograph taken by Apollo 17.[7] In addition to an imaging camera, a radiometer would take the first direct measurements of how much sunlight is reflected and emitted from the whole Earth (albedo). This data could constitute a barometer for the process of global warming. The scientific goals expanded to measure the amount of solar energy reaching Earth, cloud patterns, weather systems, monitor the health of Earth's vegetation, and track the amount of UV light reaching the surface through the ozone layer.

In 1999, NASA's Inspector General reported that "the basic concept of the Triana mission was not peer reviewed", and "Triana's added science may not represent the best expenditure of NASA's limited science funding".[8] Members of the U.S. Congress asked the National Academy of Sciences whether the project was worthwhile. The resulting report, released March 2000, stated that the mission was "strong and scientifically vital".[9]

The Bush administration put the project on hold shortly after George W. Bush's inauguration in January 2001.[6] Triana was removed from its original launch opportunity on STS-107 (the ill-fated Columbia mission in 2003).[3] The $150 million[3] spacecraft was placed into nitrogen blanketed storage at Goddard Space Flight Center in November 2001 and remained there for the duration of the Bush administration.[10] NASA renamed the spacecraft Deep Space Climate Observatory (DSCOVR) in 2003 in an attempt to regain support for the project,[3] but the mission was formally terminated by NASA in 2005.[11]

In November 2008, funded by NOAA and the U.S. Air Force, the spacecraft was removed from storage and underwent testing to determine its viability for launch.[12][13] After the Obama administration took presidency in 2009, that year's budget included $9 million marked for refurbishment and readiness of the spacecraft,[14] resulting in NASA refurbishing the EPIC instrument and recalibrating the NISTAR instrument.[15] Al Gore used part of his book Our Choice (2009) as an attempt to revive debate on the DSCOVR payload. The book mentions legislative efforts by senators Barbara Mikulski and Bill Nelson to get the spacecraft launched.[16] In February 2011, the Obama administration attempted to secure funding to re-purpose the DSCOVR spacecraft as a solar observatory to replace the aging Advanced Composition Explorer (ACE) spacecraft, and requested $47.3 million in the 2012 fiscal budget toward this purpose.[11] Part of this funding was to allow the Naval Research Laboratory to construct a coronal mass ejection imager for the spacecraft, but the time required would have delayed DSCOVR's launch and it was ultimately not included.[1][11] NOAA allocated $2 million in its 2011 budget to initiate the refurbishment effort, and increased funding to $29.8 million in 2012.[3]

In 2012, the Air Force allocated $134.5 million to procure a launch vehicle and fund launch operations, both of which were awarded to SpaceX for their Falcon 9 rocket.[3][17] In September 2013, NASA cleared DSCOVR to proceed to the implementation phase targeting an early 2015 launch,[18] which ultimately took place on February 11, 2015.[12] NASA's Goddard Space Flight Center is providing management and systems engineering to the mission.

In the 2017 documentary An Inconvenient Sequel: Truth to Power, Al Gore speaks of the history of the DSCOVR spacecraft and its relation to climate change.[19]

Spacecraft[edit]

Diagram of DSCOVR

DSCOVR is built on the SMEX-Lite spacecraft bus and has a launch mass of approximately 570 kg (1,257 lb). The main science instrument sets are the Sun-observing Plasma Magnetometer (PlasMag) and the Earth-observing NIST Advanced Radiometer (NISTAR) and Earth Polychromatic Imaging Camera (EPIC). DSCOVR has two deployable solar arrays, a propulsion module, boom, and antenna.[20]

From its vantage point, DSCOVR monitors variable solar wind conditions, provides early warning of approaching coronal mass ejections and observes phenomena on Earth, including changes in ozone, aerosols, dust and volcanic ash, cloud height, vegetation cover and climate. At its Sun–Earth L1 location it has a continuous view of the Sun and of the sunlit side of the Earth. After the spacecraft arrived on site and entered its operational phase, NASA began releasing near-real-time images of Earth through the EPIC instrument's website.[21] DSCOVR takes full-Earth pictures about every two hours and is able to process them faster than other Earth observation satellites.[22]

The spacecraft orbits the L1 point in a six-month period, with a spacecraft–Earth–Sun angle varying from 4 to 15 degrees.[23][24]

Instruments[edit]

PlasMag[edit]

The Plasma-Magnetometer (PlasMag) measures solar wind for space weather predictions. It has the capability of providing early warning detection of solar activity that could cause damage to existing satellite systems and ground infrastructure. Because solar particles reach L1 about an hour before Earth, PlasMag can provide a warning of 15 to 60 minutes before a coronal mass ejection (CME) arrives.[25] It has the capability of doing this by measuring "the magnetic field and the velocity distribution functions of the electron, proton and alpha particles (Helium nuclei) of solar wind".[26] It has three instruments:[26]

  • Magnetometer measures magnetic field.
  • Faraday cup measures positively charged particles.
  • Electrostatic analyzer measures electrons.

EPIC[edit]

The first EPIC image, released by NASA on July 6, 2015, shows the full sunlit Earth from 916,651 mi (1,475,207 km) away, centered on the Americas.[27][28]

The Earth Polychromatic Imaging Camera (EPIC) takes images of the sunlit side of Earth for various Earth science monitoring purposes in ten different channels from ultraviolet to near-infrared. Ozone and aerosol levels are monitored along with cloud dynamics, properties of the land, and vegetations.[29]

EPIC has an aperture diameter of 30.5 cm (12 in), a focal ratio of 9.38, a field of view of 0.61°, and an angular sampling resolution of 1.07 arcseconds. Earth's apparent diameter varies from 0.45° to 0.53° full width. Exposure time for each of the 10 narrowband channels (317, 325, 340, 388, 443, 552, 680, 688, 764, and 779 nm) is about 40 ms. The camera produces 2048 × 2048 pixel images, but to increase the number of downloadable images to ten per hour the resolution is averaged to 1024 × 1024 on board. The final resolution is 25 km/pixel (16 mi/pixel).[29]

NISTAR[edit]

The National Institute of Standards and Technology Advanced Radiometer (NISTAR) was designed and built between 1999 and 2001 by Ball Aerospace in Gaithersburg, Maryland. NISTAR measures irradiance of the sunlit face of the Earth. This means that NISTAR measures if the Earth's atmosphere is taking in more or less solar energy than it is radiating back towards space. This data is to be used to study changes in Earth's radiation budget caused by natural and human activities.[30]

Using NISTAR data, scientists can help determine the impact that humanity is having on Earth's atmosphere and make the necessary changes to help balance the radiation budget.[31] The radiometer measures in four channels:

  • For total radiation in ultraviolet, visible and infrared in the range 0.2–100 µm
  • For reflected solar radiation in ultraviolet, visible and near-infrared in the range 0.2–4 µm
  • For reflected solar radiation in infrared in the range 0.7–4 µm
  • For calibration purposes in the range 0.3–1 µm

Launch[edit]

The DSCOVR launch was conducted by launch provider SpaceX using their Falcon 9 v1.1 rocket. The launch of DSCOVR took place on February 11, 2015, following two scrubbed launches. It took DSCOVR 110 days from when it left Cape Canaveral Air Force Station, Florida, to reach its target destination 1.5 million km away from Earth at the L1 Lagrangian point.[32][33]

Launch attempt history[edit]

Attempt Planned Result Turnaround Reason Decision point Weather go (%) Notes
1 8 Feb 2015, 11:10:00 pm Scrubbed Technical  (T02:30:00) >90 Range issues: tracking,[34] first-stage video transmitter issues noted
2 10 Feb 2015, 11:04:49 pm Scrubbed 1 day, 23 hours, 55 minutes Weather 80 Upper-level winds at the launch pad exceeded 100 knots (190 km/h; 120 mph) at 25,000 feet (7,600 m)
3 11 Feb 2015, 11:03:32 pm Success 0 days, 23 hours, 59 minutes >90

Post-launch flight test[edit]

SpaceX planned to conduct a test flight where they would attempt to bring the first stage back through the atmosphere and land the expended first stage on a 90-by-50-meter (300 ft × 160 ft) floating landing platform.[35][36]

Relative to earlier tests, the first-stage return on DSCOVR was much more challenging, especially in atmospheric reentry due to the deep-space nature of the Earth–Sun L1 launch trajectory for DSCOVR. This would only be the second time that SpaceX ever tried to recover the first stage of the Falcon 9 payload.[32] SpaceX expected deceleration-force loads to be twice as high and rocket heating to quadruple over the reentry conditions on Falcon 9 Flight 14.[37] Before the launch, the drone ship was in ocean surface conditions that made the barge landing infeasible. Therefore, the landing platform attempt was called off, and the first stage made an over-water soft landing instead. This continued the collection of returnable first-stage test data on all the earlier phases of the flight test and added data on stage survival following a high-speed, high-load atmospheric entry.[38]

Operation[edit]

Animation of Deep Space Climate Observatory's trajectory
Oblique view
Viewed from the Sun
  Deep Space Climate Observatory ·   Earth ·   Moon

On July 6, 2015, DSCOVR returned its first publicly released view of the entire sunlit side of Earth from 1,475,207 km (916,651 mi) away, taken by the EPIC instrument. EPIC provides a daily series of Earth images, enabling the first-time study of daily variations over the entire globe. The images, available 12 to 36 hours after they are made, have been posted to a dedicated web page since September 2015.[27][28]

DSCOVR was placed in operation at the L1 Lagrangian point to monitor the Sun, because the constant stream of particles from the Sun (the solar wind) reaches L1 about 60 minutes before reaching Earth. DSCOVR will usually be able to provide a 15- to 60-minute warning before a surge of particles and magnetic field from a coronal mass ejection (CME) reaches Earth and creates a geomagnetic storm. DSCOVR data will also be used to improve predictions of the impact locations of a geomagnetic storm to be able to take preventative action. Electronic technologies such as satellites in geosynchronous orbit are at risk of unplanned disruptions without warnings from DSCOVR and other monitoring satellites at L1.[25]

On July 16–17, 2015, DSCOVR took a series of images showing the Moon engaged in a transit of Earth. The images were taken between 19:50 and 00:45 UTC. The animation was composed of monochrome images taken in different color filters at 30-second intervals for each frame, resulting in a slight color fringing for the Moon in each finished frame. Due to its position at Sun–Earth L1, DSCOVR will always see the Moon illuminated and will always see its far side when it passes in front of Earth.[39]

On October 19, 2015, NASA opened a new website to host near-live "Blue Marble" images taken by EPIC of Earth.[21] Twelve images are released each day, every two hours, showcasing Earth as it rotates on its axis.[40] The resolution of the images ranges from 10 to 15 km per pixel (6.2 to 9.4 mi/pixel), and the short exposure times renders points of starlight invisible.[40]

As of June 27, 2019, DSCOVR has been in safe mode and is not returning scientific data or images.[41] It is expected the spacecraft will return to operation early in 2020 after a software fix is installed. [42]

Animations[edit]

The Moon transiting Earth, July 16, 2015. The far side of the Moon faces the camera.
Earth depicted with its 23.4° tilt (the cause of the seasons) on EPIC's 268th day of operation, September 25, 2015, a few days after the September equinox
Earth's rotation on May 29, 2016, a few weeks prior to the June solstice, with the Northern Hemisphere tilted toward the Sun
From space, the Moon's shadow during the solar eclipse of March 9, 2016 appears as a dark spot moving across the Earth.

See also[edit]

References[edit]

  1. ^ a b c d "NOAA Satellite and Information Service: Deep Space Climate Observatory (DSCOVR)" (PDF). NOAA. Retrieved September 24, 2019.
  2. ^ a b "DSCOVR: Deep Space Climate Observatory" (PDF). NOAA. January 2015. Archived from the original (PDF) on April 2, 2015. Retrieved March 14, 2015.
  3. ^ a b c d e f g Mellow, Craig (August 2014). "Al Gore's Satellite". Air & Space/Smithsonian. Retrieved December 12, 2014.
  4. ^ Boyle, Alan (February 10, 2015). "SpaceX Scrubs Falcon 9's DSCOVR Launch (Again) Due to Winds". NBC News. Retrieved February 15, 2015.
  5. ^ "DSCOVR completes its first year in deep space!". NOAA. March 7, 2016. Retrieved March 12, 2019.
  6. ^ a b Donahue, Bill (April 7, 2011). "Who killed the Deep Space Climate Observatory?". Popular Science. Retrieved December 12, 2014.
  7. ^ Leary, Warren (June 1, 1999). "Politics Keeps a Satellite Earthbound". The New York Times. Retrieved July 24, 2009.
  8. ^ "Assessment of the Triana Mission, G-99-013, Final Report" (PDF). Office of Inspector General. NASA. September 10, 1999. Archived from the original (PDF) on March 20, 2009. Retrieved February 7, 2009.
  9. ^ "NASA's Triana Mission Scientific Evaluation Completed". Earth Observatory. NASA. March 8, 2000. Archived from the original on October 11, 2008. Retrieved February 3, 2008.
  10. ^ Clark, Stephen (March 2, 2009). "Mothballed satellite sits in warehouse, waits for new life". Spaceflight Now. Retrieved March 2, 2009.
  11. ^ a b c Clark, Stephen (February 21, 2011). "NOAA taps DSCOVR satellite for space weather mission". Spaceflight Now. Archived from the original on February 24, 2011.
  12. ^ a b Siddiqi, Asif A. (2018). Beyond Earth: A Chronicle od Deep Space Exploration, 1958-2016 (PDF). NASA. p. 303. ISBN 978-1-62683-043-1. LCCN 2017058675.
  13. ^ "Triana/DSCOVR Spacecraft Successfully Revived from Mothballs". NASA. February 15, 2009. Archived from the original on June 12, 2009. Retrieved September 7, 2009.
  14. ^ Donahue, Bill (April 6, 2011). "Who Killed The Deep Space Climate Observatory?". Popular Science. Retrieved September 24, 2019.
  15. ^ Smith, R. C.; et al. (December 2011). "Earth Science Instrument Refurbishment, Testing and Recalibration for the Deep Space Climate Observatory (DSCOVR)". Bibcode:2011AGUFM.A43G..03S. Cite journal requires |journal= (help)
  16. ^ Gore, Al (2009). "Chapter 17". Our Choice. Rodale. ISBN 978-1-59486-734-7.
  17. ^ "Spacex awarded two EELV-class missions from the United States Air Force" (Press release). SpaceX. December 5, 2012. Retrieved December 12, 2014.
  18. ^ Leslie, John (September 10, 2013). "DSCOVR Mission Moves Forward to 2015 Launch". NASA/NOAA. Retrieved September 10, 2013.
  19. ^ Adams, Sam (January 20, 2017). "Film review: Is Al Gore's An Inconvenient Sequel worthwhile?". BBC. Retrieved May 30, 2018.
  20. ^ "Spacecraft and Instruments". NOAA. Archived from the original on February 9, 2015. Retrieved February 10, 2015.
  21. ^ a b "DSCOVR: EPIC – Earth Polychromatic Imaging Camera". NASA. Retrieved August 30, 2019.
  22. ^ Phillips, Ari (February 4, 2015). "A Sneak Peek at NASA's New Satellite That has Been 16 Years in the Making". ThinkProgress.
  23. ^ "DSCOVR Mission Hosts Two NASA Earth-Observing Instruments". NOAA. October 21, 2014. Retrieved February 9, 2015.
  24. ^ Clark, Stephen (June 7, 2015). "DSCOVR space weather sentinel reaches finish line". Spaceflight Now. Retrieved June 10, 2015.
  25. ^ a b "DSCOVR: Deep Space Climate Observatory". NOAA. Retrieved July 22, 2015.
  26. ^ a b "NOAA Satellite and Information Service: Deep Space Climate Observatory (DSCOVR): Plasma-Magnetometer (PlasMag)" (PDF). NOAA. Archived from the original (PDF) on February 10, 2015. Retrieved February 10, 2015.
  27. ^ a b Northon, Karen (July 20, 2015). "NASA Captures "EPIC" Earth Image". NASA. Retrieved July 21, 2015.
  28. ^ a b "DSCOVR: EPIC". NASA. July 6, 2015. Retrieved February 26, 2018.
  29. ^ a b "NOAA Satellite and Information Service: Deep Space Climate Observatory (DSCOVR): Enhanced Polychromatic Imaging Camera (EPIC)" (PDF). NOAA. January 14, 2015. Archived from the original (PDF) on February 10, 2015. Retrieved February 10, 2015.
  30. ^ "NOAA Satellite and Information Service: Deep Space Climate Observatory (DSCOVR): National Institute of Standards & Technology Advanced Radiometer (NISTAR)" (PDF). NOAA. Archived from the original (PDF) on April 22, 2015. Retrieved February 10, 2015.
  31. ^ Jenner, Lynn (January 20, 2015). "NOAA's DSCOVR NISTAR Instrument Watches Earth's "Budget"". NASA. Retrieved March 12, 2019.
  32. ^ a b "DSCOVR - Satellite Missions - eoPortal Directory". directory.eoportal.org. Retrieved March 12, 2019.
  33. ^ "NOAA's First Operational Satellite in Deep Space Reaches Final Orbit". NOAA. June 8, 2015. Retrieved May 1, 2019.
  34. ^ Cresswell, Miriam (February 8, 2015). "SpaceX DISCOVR launch scrubbed". Space Alabama. WAAY-TV. Archived from the original on February 11, 2015. Retrieved April 2, 2015.
  35. ^ Bergin, Chris (December 17, 2014). "SpaceX confirms CRS-5 launch slip to January 6". NASA Spaceflight. Retrieved December 24, 2014.
  36. ^ Graham, William (February 8, 2015). "SpaceX Falcon 9 ready for DSCOVR mission". NASA Spaceflight. Retrieved February 8, 2015.
  37. ^ Musk, Elon (February 8, 2015). "Rocket reentry will be much tougher..." Twitter.com. Retrieved February 8, 2015.
  38. ^ Wall, Mike (February 11, 2015). "SpaceX Won't Try Rocket Landing on Drone Ship After Satellite Launch Today". Space.com. Retrieved March 20, 2015.
  39. ^ Clark, Stephen (August 5, 2015). "Watch the moon transit the Earth". Spaceflight Now. Retrieved August 6, 2015.
  40. ^ a b Clark, Stephen (October 19, 2015). "NASA to post new 'blue marble' pictures every day". Spaceflight Now. Retrieved October 19, 2015.
  41. ^ Foust, Jeff (July 5, 2019). "DSCOVR spacecraft in safe mode". SpaceNews. Retrieved August 12, 2019.
  42. ^ https://spacenews.com/software-fix-planned-to-restore-dscovr/

External links[edit]

Further reading[edit]