{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T17:22:49Z","timestamp":1790961769227,"version":"4.1.0"},"reference-count":37,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2019,4,3]],"date-time":"2019-04-03T00:00:00Z","timestamp":1554249600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000104","name":"National Aeronautics and Space Administration","doi-asserted-by":"publisher","award":["NNX13AM53G"],"award-info":[{"award-number":["NNX13AM53G"]}],"id":[{"id":"10.13039\/100000104","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000104","name":"National Aeronautics and Space Administration","doi-asserted-by":"publisher","award":["80NSSC18K1523"],"award-info":[{"award-number":["80NSSC18K1523"]}],"id":[{"id":"10.13039\/100000104","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) 3U CubeSat mission is a pathfinder to demonstrate technologies for the measurement of Earth\u2019s radiation budget, the quantification of which is critical for predicting the future course of climate change. A specific motivation is the need for lower-cost technology alternatives that could be used for multi-point constellation measurements of Earth outgoing radiation. RAVAN launched 11 November 2016, into a nearly 600-km, Sun-synchronous orbit, and collected data for over 20 months. RAVAN successfully demonstrates two key technologies. The first is the use of vertically aligned carbon nanotubes (VACNTs) as absorbers in broadband radiometers for measuring Earth\u2019s outgoing radiation and the total solar irradiance. VACNT forests are arguably the blackest material known and have an extremely flat spectral response over a wide wavelength range, from the ultraviolet to the far infrared. As radiometer absorbers, they have greater sensitivity for a given time constant and are more compact than traditional cavity absorbers. The second technology demonstrated is a pair of gallium phase-change black body cells that are used as a stable reference to monitor the degradation of RAVAN\u2019s radiometer sensors on orbit. Four radiometers (two VACNT, two cavity), the pair of gallium black bodies, and associated electronics are accommodated in the payload of an agile 3U CubeSat bus that allows for routine solar and deep-space attitude maneuvers, which are essential for calibrating the Earth irradiance measurements. The radiometers show excellent long-term stability over the course of the mission and a high correlation between the VACNT and cavity radiometer technologies. Short-term variability\u2014at greater than the tenths-of-a-Watt\/m2 needed for climate accuracy\u2014is a challenge that remains, consistent with insufficient thermal knowledge and control on a 3U CubeSat. There are also VACNT\u2013cavity biases of 3% and 6% in the Total and SW channels, respectively, which would have to be overcome in a future mission. Although one of the black bodies failed after four months, the other provided a repeatable standard for the duration of the project. We present representative measurements from the mission and demonstrate how the radiometer time series can be used to reconstruct outgoing radiation spatial information. Improvements to the technology and approach that would lead to better performance and greater accuracy in future missions are discussed.<\/jats:p>","DOI":"10.3390\/rs11070796","type":"journal-article","created":{"date-parts":[[2019,4,4]],"date-time":"2019-04-04T03:13:42Z","timestamp":1554347622000},"page":"796","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":28,"title":["RAVAN: CubeSat Demonstration for Multi-Point Earth Radiation Budget Measurements"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9172-7189","authenticated-orcid":false,"given":"William H.","family":"Swartz","sequence":"first","affiliation":[{"name":"Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Steven R.","family":"Lorentz","sequence":"additional","affiliation":[{"name":"L-1 Standards and Technology, Manassas, VA 20109, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stergios J.","family":"Papadakis","sequence":"additional","affiliation":[{"name":"Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Philip M.","family":"Huang","sequence":"additional","affiliation":[{"name":"Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Allan W.","family":"Smith","sequence":"additional","affiliation":[{"name":"L-1 Standards and Technology, Manassas, VA 20109, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David M.","family":"Deglau","sequence":"additional","affiliation":[{"name":"Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yinan","family":"Yu","sequence":"additional","affiliation":[{"name":"L-1 Standards and Technology, Manassas, VA 20109, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sonia M.","family":"Reilly","sequence":"additional","affiliation":[{"name":"Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nolan M.","family":"Reilly","sequence":"additional","affiliation":[{"name":"Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Donald E.","family":"Anderson","sequence":"additional","affiliation":[{"name":"Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,4,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"316","DOI":"10.1126\/science.1187272","article-title":"Tracking Earth\u2019s Energy","volume":"328","author":"Trenberth","year":"2010","journal-title":"Science"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"13421","DOI":"10.5194\/acp-11-13421-2011","article-title":"Earth\u2019s energy imbalance and implications","volume":"11","author":"Hansen","year":"2011","journal-title":"Atmos. Chem. Phys."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"691","DOI":"10.1038\/ngeo1580","article-title":"An update on Earth\u2019s energy balance in light of the latest global observations","volume":"5","author":"Stephens","year":"2012","journal-title":"Nat. Geosci."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Allan, R.P., Liu, C., Loeb, N.G., Palmer, M.D., Roberts, M., Smith, D., and Vidale, P.L. (2014). Changes in global net radiative imbalance 1985\u20132012. Geophys. Res. Lett., 41.","DOI":"10.1002\/2014GL060962"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"3129","DOI":"10.1175\/JCLI-D-13-00294.1","article-title":"Earth\u2019s Energy Imbalance","volume":"27","author":"Trenberth","year":"2014","journal-title":"J. Clim."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"138","DOI":"10.1038\/nclimate2876","article-title":"An imperative to monitor Earth\u2019s energy imbalance","volume":"6","author":"Palmer","year":"2016","journal-title":"Nat. Clim. Chang."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Dewitte, S., and Clerbaux, N. (2017). Measurement of the Earth Radiation Budget at the Top of the Atmosphere\u2014A Review. Remote Sens., 9.","DOI":"10.3390\/rs9111143"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Intergovernmental Panel on Climate Change (IPCC) (2013). Climate Change 2013: The Physical Science Basis, Cambridge University Press.","DOI":"10.1017\/CBO9781107415324"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"311","DOI":"10.1175\/2008BAMS2634.1","article-title":"Earth\u2019s Global Energy Budget","volume":"90","author":"Trenberth","year":"2009","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Kopp, G., and Lean, J. (2011). A new, lower value of total solar irradiance: Evidence and climate significance. Geophys. Res. Lett., 38.","DOI":"10.1029\/2010GL045777"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"357","DOI":"10.1029\/RG024i002p00357","article-title":"History of Satellite Missions and Measurements of the Earth Radiation Budget (1957\u20131984)","volume":"24","author":"House","year":"1986","journal-title":"Rev. Geophys."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"4107","DOI":"10.1029\/JD092iD04p04107","article-title":"Earth Radiation Budget Wide Field of View Climate Data Set Improvement, 1. The Earth Albedo from Deconvolution of Shortwave Measurements","volume":"92","author":"Hucek","year":"1987","journal-title":"J. Geophys. Res."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1085","DOI":"10.1175\/1520-0450(1990)029<1085:TCIONW>2.0.CO;2","article-title":"The Constrained Inversion of Nimbus-7 Wide Field-of-View Radiometer Measurements for the Earth Radiation Budget","volume":"29","author":"Hucek","year":"1990","journal-title":"J. Appl. Meteorol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1114","DOI":"10.1002\/2016JD025514","article-title":"Determination of global Earth outgoing radiation at high temporal resolution using a theoretical constellation of satellites","volume":"122","author":"Gristey","year":"2017","journal-title":"J. Geophys. Res."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"240","DOI":"10.1175\/1520-0450(2003)042<0240:ADMFTO>2.0.CO;2","article-title":"Angular Distribution Models for Top-of-Atmosphere Radiative Flux Estimation from the Clouds and the Earth\u2019s Radiant Energy System Instrument on the Tropical Rainfall Measuring Mission Satellite. Part I: Methodology","volume":"42","author":"Loeb","year":"2003","journal-title":"J. Appl. Meteorol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1170","DOI":"10.1175\/1520-0477(1984)065<1170:TERBE>2.0.CO;2","article-title":"The Earth Radiation Budget Experiment (ERBE)","volume":"65","author":"Barkstrom","year":"1984","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"853","DOI":"10.1175\/1520-0477(1996)077<0853:CATERE>2.0.CO;2","article-title":"Clouds and the Earth\u2019s Radiant Energy System (CERES): An Earth Observing System Experiment","volume":"77","author":"Wielicki","year":"1996","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"945","DOI":"10.1175\/BAMS-86-7-945","article-title":"The Geostationary Earth Radiation Budget Project","volume":"86","author":"Harries","year":"2005","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"7495","DOI":"10.1175\/JCLI-D-16-0339.1","article-title":"Insights into Earth\u2019s Energy Imbalance from Multiple Sources","volume":"29","author":"Trenberth","year":"2016","journal-title":"J. Clim."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Loeb, N.G., Wielicki, B.A., Wong, T., and Parker, P.A. (2009). Impact of data gaps on satellite broadband radiation records. J. Geophys. Res., 114.","DOI":"10.1029\/2008JD011183"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1519","DOI":"10.1175\/BAMS-D-12-00149.1","article-title":"Achieving Climate Change Absolute Accuracy in Orbit","volume":"94","author":"Wielicki","year":"2013","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"648","DOI":"10.1063\/1.4804853","article-title":"The Next Step in Earth Radiation Budget Measurements","volume":"1531","author":"Wiscombe","year":"2013","journal-title":"AIP Conf. Proc."},{"key":"ref_23","unstructured":"National Academy of Sciences (2016). Achieving Science with CubeSats: Thinking Inside the Box, National Academies Press."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"5936","DOI":"10.1109\/TGRS.2018.2828783","article-title":"On the Lessons Learned From the Operations of the ERBE Nonscanner Instrument in Space and the Production of the Nonscanner TOA Radiation Budget Data Set","volume":"56","author":"Wong","year":"2018","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Swartz, W.H., Dyrud, L.P., Lorentz, S.R., Wu, D.L., Wiscombe, W.J., Papadakis, S.J., Huang, P.M., Reynolds, E.L., Smith, A., and Deglau, D.M. (2015, January 26\u201331). The RAVAN CubeSat mission: Advancing technologies for climate observation. Proceedings of the 2015 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Milan, Italy.","DOI":"10.1109\/IGARSS.2015.7327031"},{"key":"ref_26","unstructured":"Swartz, W.H., Lorentz, S.R., Huang, P.M., Smith, A.W., Deglau, D.M., Liang, S.X., Marcotte, K.M., Reynolds, E.L., Papadakis, S.J., and Dyrud, L.P. (2016, January 6\u201311). The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat mission: A pathfinder for a new measurement of Earth\u2019s radiation budget. Proceedings of the 30th Annual AIAA\/USU Conference on Small Satellites, Logan, UT, USA. number SSC16-XII-03."},{"key":"ref_27","unstructured":"Swartz, W.H., Lorentz, S.R., Huang, P.M., Smith, A.W., Carvo, J., Deglau, D.M., Reynolds, E.L., Papadakis, S.J., and Wu, D.L. (2017, January 24\u201328). The RAVAN CubeSat mission: A pathfinder for a new measurement of Earth\u2019s energy budget. Proceedings of the 11th IAA Symposium on Small Satellites for Earth Observation, Berlin, Germany."},{"key":"ref_28","unstructured":"Swartz, W.H., Huang, P.M., Reynolds, E.L., Lorentz, S.R., Smith, A.W., Briscoe, J., Carvo, J., and Wu, D.L. (2017, January 5\u201310). RAVAN CubeSat results: Technologies and science demonstrated on orbit. Proceedings of the 31st Annual AIAA\/USU Conference on Small Satellites, Logan, UT, USA. number SSC17-X-07."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1007\/s11207-005-7446-4","article-title":"The Total Irradiance Monitor (TIM): Instrument Design","volume":"230","author":"Kopp","year":"2005","journal-title":"Sol. Phys."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"011103","DOI":"10.1063\/1.5009190","article-title":"Carbon nanotube-based black coatings","volume":"5","author":"Lehman","year":"2018","journal-title":"Appl. Phys. Rev."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"6044","DOI":"10.1073\/pnas.0900155106","article-title":"A black body absorber from vertically aligned single-walled carbon nanotubes","volume":"106","author":"Mizuno","year":"2009","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"329","DOI":"10.1016\/j.carbon.2014.03.040","article-title":"Decrease in reflectance of vertically-aligned carbon nanotubes after oxygen plasma treatment","volume":"74","author":"Tomlin","year":"2014","journal-title":"Carbon"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"15009","DOI":"10.1038\/npjmgrav.2015.9","article-title":"Observational study: microgravity testing of a phase-change reference on the International Space Station","volume":"1","author":"Topham","year":"2015","journal-title":"Microgravity"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Han, S.C., Rowlands, D.D., Luthcke, S.B., and Lemoine, F.G. (2008). Localized analysis of satellite tracking data for studying time-variable Earth\u2019s gravity fields. J. Geophys. Res., 113.","DOI":"10.1029\/2007JB005218"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1176","DOI":"10.1175\/1520-0469(1988)045<1176:ASCFWF>2.0.CO;2","article-title":"Asynoptic Sampling Considerations for Wide-Field-of-View Measurements of Outgoing Radiation. Part I: Spatial and Temporal Resolution","volume":"45","author":"Salby","year":"1988","journal-title":"J. Atmos. Sci."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1184","DOI":"10.1175\/1520-0469(1988)045<1184:ASCFWF>2.0.CO;2","article-title":"Asynoptic Sampling Considerations for Wide-Field-of-View Measurements of Outgoing Radiation. Part II: Diurnal and Random Space\u2013Time Variability","volume":"45","author":"Salby","year":"1988","journal-title":"J. Atmos. Sci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"5419","DOI":"10.1175\/JCLI-D-16-0758.1","article-title":"The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2)","volume":"30","author":"Gelaro","year":"2017","journal-title":"J. Clim."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/7\/796\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:42:37Z","timestamp":1760186557000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/7\/796"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,4,3]]},"references-count":37,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2019,4]]}},"alternative-id":["rs11070796"],"URL":"https:\/\/doi.org\/10.3390\/rs11070796","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,4,3]]}}}