CURRENT HOT RESEARCH TOPIC and RECENT WORK (2003-2018). Click on paper title to see abstract, if available. 

Understanding the internal structure of comet nuclei and its evolution has long been considered a pre-requisite for understanding how they were formed. During NASA's Deep Impact mission in 2005 it was discovered that the interior of comet 9P/Tempel 1 had a deep system of layers which were thought to be due to deformation of cometesimals as they collided to build-up the nucleus. Now, as a result of extremely high-spatial resolution imaging of cliffs and surface features on comet 67P/Churyumov-Gerasimenko from ESA's Rosetta orbiter, it has been discovered that essentially the entire interiors of the two lobes of this bi-lobate comet  are dominated by separate systems of strata that are each coordinated over global scales. This presents an enormous interpretive challenge. At Belton Space we are investigating the possibility that these strata were formed  late in the comet's evolution, during its late Centaur stage (about 106 year ago), when the original water-ice in the nucleus underwent a phase change from the amorphous form to the crystalline form. Triggered at the surface as it warmed under solar insolation to ~110 - 120 deg K, the phase change propagated into the interior at varying rates forming the strata.

On the origin of internal layers in comet nuclei

Michael J.S. Belton, Xiao-Duan Zou, Jang-Yang Li, and Erik Asphaug, Submitted to Icarus on 1/29/2018

The excited spin state of 1I/2017 U1 'Oumuamua

Michael J.S. Belton, Oliver R. Hainaut, Karen J. Meech, Beatrice E.A. Mueller, Jan T. Kleyna, Harold A. Weaver, Marc W. Buie, Michal Drahus, Piotr Guzik, Richard J. Wainscoat, Waclaw Waniak, Barbara Handzlik, Sebastian Kurowski, Siyi Zu, Scott S. Sheppard, Marco Micheli, Harald Ebeling, and Jacqueline V. Keane. Submitted to Astrophysical Journal Letters, 25 Dec, 2018

Michael F. A'Hearn. Obituary

Michael J.S. Belton, 2017, Nature Astronomy, 1, 644-645

Hyperactivity in 103P/Hartley 2: Chunks from the sub-surface in type IIa jet regions.

Michael J.S. Belton, 2017. Icarus 285, 58-67.

The mass disruption of Jupiter Family comets.

 Michael J.S. Belton, 2014. Icarus  245, 87-93.

The size-distribution of scattered disk TNOs from that of JFCs between 0.2 and 15 km effective radius

Michael J.S. Belton. 2014. Icarus  231, 168-182.

The complex spin state of 103P/Hartley 2: Kinematics and orientation in space.

Michael J.S. Belton, Peter Thomas, Jian-Yang Li, Jade Williams, Brian Carcich, Michal F. A'Hearn, Stephanie McLaughlin, Tony Farnham, Lucy McFadden, Carey, M. Lisse, Steven Collins, Sebastien Besse, Kenneth Klaasen, Jessics Sunshine, Karen J, Meech, Don Lindler. 2013. Icarus 222, 595-609.

The source of the unusual dust jets seen in comet 103P/Hartley 2.

Michael J.S. Belton. 2013. Icarus 222, 653-661.

Chandra ACIS-S imaging spectroscopy of anomalously faint X-ray emission from comet 103P/Hartley 2 during the EPOXI encounter.

C.M. Lisse, D.J. Christian, S.J. Volk, K. Dennerl, D. Bodewits, M.R. Combi, S.T. Lepri, T.H. Zurbuchen, J.Y. Li. N. Dello-Russo, M.J.S. Belton, M.M. Knight. 2013. Icarus 222, 752-765.

The temperature, thermal inertia, roughness, and color of the nuclei of comet 103P/Hartley 2 and 9P/Tempel 1.

O. Groussin, J.M. Sunshine, L.M. Feaga, L. Jorda, P.C. Thomas, J-Y. Li, M.F. A'Hearn, M.J.S. Belton, S. Besse, B; Carcich, T.L. Farnham, D. Hampton, K. Klaasen, C. Lisse, F. Merlin, S. Protopapa. 2013. Icarus 222, 580-594.

Photometric properties of the nucleus of comet 103P/Hartley 2.

Jian-Yang Li, Sebastien Besse, Michael F. A'Hearn, Michael J.S. Belton, Dennis Bodewits, Tony L. Farnham, Kenneth P. Klaasen, Carey M. Lisse, Karen J. Meech, Jessica, M. Sunshine, Peter C. Thomas. 2013. Icarus 222, 559-570.

Shape, density, and geology of the nucleus of comet 103P/Hartley 2.

Thomas, P.C., A'Hearn, M.F., Veverka, J., Belton, M.J.S., Kissel, J., Klaasen, K.P., McFadden, L.A., Melosh, H.J., Schulz, P.H., Besse, S., Carcich, B.C., Farnham, T.L., Groussin, O., Hermalyn, B., Li, J-Y., Lindler, D.J., Lisse, C.M., Meech, K., Richardson, J.E. 2013. Icarus 222, 550-558.

The origin of pits on 9P/Tempel 1 and the geologic signature of outbursts in Stardust-NExT images.

Belton, M.J.S., Thomas, P., Carcich, B., Quick, A., Veverka, J., Melosh, H.J., AHearn, M.F., Li, J-Y., Brownlee,D.,  Schultz, P., Klaasen, K., Sarid, G. 2013.  Icarus.222, 477-486.

The nucleus of comet 9P/Tempel 1: Shape and geology from two flybys.

Thomas, P.C, AHearn, M.F., Belton, M.J.S., Brownlee, D.,Carcich, B., Hermalyn, B., Klaasen, K., Sackett, S., Schultz, P., Veverka, J.,S., Bodewits, D. Chesley, S., Bhaskaren, S., Farnham, T., Groussin, O. Harris, A., Kissel, J., Li, J-Y., Meech, K.J., Melosh, J., Quick, A., Richardson, J., Sunshine, J., Wellnitz, D. 2013, Icarus. 222, 453-466.                               

Photometry of comet 9P/Tempel 1 from Stardust-NExT flyby and the implications.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  

Li, J-Y., AHearn, M.F., Belton, M.J.S., Farnham, T.L., Klaasen, K.P., Sunshine, J.M.,Thomas, P.C., Veverka, J. 2013, Icarus. 222, 467-476.         

Connections between the jet activity and surface features on comet 9P/Tempel 1.  

Farnham, T.L., Bodewits, D., Li, J.-Y., Veverka, J., Thomas, P., and Belton, M.J.S.    2013. Icarus 222, 540-549.

           An updated rotation model for comet 9P/Tempel 1.


Chesley, S.R., Belton, M.J.S., Carcich, B., Thomas, P.C., Pittichova, J., Klaasen, K.P.,Li, J.-Y., Farnham, T.L., Gillam, S.D., Harris, A.W., Veverka, J.  2013. Icarus 222, 516-525.             


Cometary Evolution and Cryo-volcanism  

             Michael J.S. Belton 2012, Canadian J. Phys.90, 807-815.

Return to comet 9P/Tempel 1: Overview of Stardust-NExT results.

Veverka, J., Klaasen, K., AHearn, M., Belton, M., Brownlee, D., Chesley, S., Clark, B., Economou, T., Fahrquar, R., Green, S.F., Groussin, O., Harris, A., Kissel, J., Li, J-Y., Meech, K., Melosh, J., Richardson, J., Schultz, P., Silen, J., Sunshine, J., Thomas, P., Bhaskaran, S., Bodewits, D., Carcich, B., Cheuvront, A., Farnham, T., Sackett, S.,Wellnitz, D., Wolf, A.  2013. Icarus, 222, 424-435.        

EPOXI at Comet Hartley 2


Michael F. A'Hearn, Michael J.S. Belton, W. Alan Delamere, Lori M. Feaga, Donald Hampton, Jochen Kissel, Kenneth P. Klaasen, Lucy A. McFadden, Karen J. Meech, H. Jay Melosh,  Peter H. Schultz, Jessica M. Sunshine, Peter C. Thomas, Joseph Veverka, Dennis D Wellnitz, Donald K. Yeomans, Sebastien Besse, Dennis Bodewits, Timothy J. Bowling, Brian T. Carcich, Steven M. Collins, Tony L. Farnham, Oliver Groussin Brendan Hermalyn, Michael S. Kelley, Jian-Yang Li, Stephanie A McLaughlin, Silvia Protopapa, James E. Richardson, Jade A. Williams. 2011, Science, 332, 1396-1400.

Stardust-NExT, Deep Impact, and the accelerating spin of 9P/Tempel 1

Michael J.S. Belton, Karen J. Meech, Steven Chesley, Jana Pittichova, Brian Carcich, Michal Drahus, Alan Harris, Stephen Gillam, Joseph Veverka, Nicholas Mastrodemos, William Owen, Michael F. AHearn, S. Bagnulo, J. Bai, L. Barrera, Fabienne Bastien, James M. Bauer, J. Bedient, B. C. Bhatt, Hermann Boehnhardt, N. Brosch, Marc Buie, Pablo Candia, W.-P. Chen, P. Chiang, Young-Jun Choi, A. Cochran, Christopher J. Crockett, S. Duddy, Tony Farnham, Yan R. Fernndez, Pedro Gutirrez, Olivier R. Hainaut, Donald Hampton, Kimberly A. Herrmann, Henry Hsieh, M. A. Kadooka, H. Kaluna, J. Keane, M.-J. Kim, Kenneth Klaasen, J. Kleyna, Kevin Krisciunas, Luisa M. Lara, Tod R. Lauer, Jian-Yang Li, Javier Licandro, C.M. Lisse, Stephen C. Lowry, Lucy McFadden, N. Moskovitz,  Beatrice Mueller, D. Polishook, N. S. Raja, T. Riesen, D. K. Sahu, Nalin Samarasinha, G.Sarid, Tomohiko Sekiguchi , S. Sonnett,  Nicholas B. Suntzeff, Brian W. Taylor, Peter Thomas, Gian Paolo Tozzi, R. Vasundhara, J.-B. Vincent, Lawrence H. Wasserman, Bryant Webster-Schultz, B. Yang, T. Zenn, H. Zhao. 2011, Icarus, 213, 345-368                  .

Deep Impact, Stardust-NExT and the behavior of Comet 9P/Tempel 1 from 1997-2010

K.J. Meech, Pittichova, J., Yang, B., Zenn, A.S., Belton, M.J., AHearn, M.F., Bagnulo, S. and  51 other co-investigators. 2010 Icarus 213, 323-344             

Cometary Activity, Active Areas, and a Mechanism for Collimated Outflows on 1P, 9P, 19P, and 81P. 

Michael J.S. Belton, 2011. Icarus. 210, 881-897

Energy balance of the Deep Impact experiment

O. Groussin, M.F. A'Hearn, M.J.S. Belton, T. Farnham, L. Feaga, J. Kissel, C. Lisse, J. Melosh, P. Schultz, J. Sunshine, J. Veverka. 2010, Icarus 205, 627-637

Cometary Ices

Carey Lisse, Akiva Bar-Nun, Diana Laufer, Michael Belton, Walter Harris, Henry Hsieh, David Jewitt. 2012. In The science of solar system ices, Ed. M. Gudipati, Springer Verlag. In press

Spitzer Space Telescope Observations of the nucleus of comet 103P/Hartley 2

C.M. Lisse, Y.R. Fernandez, W.T. Reach, J.M. Bauer, M.F. A'Hearn, T.L. Farnham, O. Groussin, M.J. Belton, and C.D. Snodgrass. Pub. Astron. Soc. Pacific, 121. 968-975.

Fluidization and multiphase transport of particulate cometary material as an explanation of the smooth terrains and repetitive outbursts on 9P/Tempel 1.

Michael J.S. Belton and H. Jay Melosh. 2009. Icarus 200, 280-291.

Cometary cryo-volcanism: Source regions and a model for the UT 2005 June 14 and other mini-outbursts on comet 9P/Tempel 1.

Michael J.S. Belton, Paul D. Feldman, Michael F. A'Hearn, and Brian Carcich.  2008. Icarus 198, 189-207.

The Accelerating Spin of 9P/Tempel 1

Michael J.S. Belton and Michal Drahus. 2007 DPS Meeting Abstract

The Internal Structure of Jupiter Family Cometary Nuclei from Deep Impact Observations: The Talps or Layered Pile Model.

M.J.S. Belton, P. Thomas, J. Veverka, P. Schultz, M. A'Hearn, L. Feaga, T. Farnham, O. Groussin, J-L Li, C. Lisse, L. McFadden, J. Sunshine, K.J. Meech, W. A. Delamere.  2007. Icarus 187, 332-344

Deep Impact Photometry of Comet  9P/Tempel 1.

Jian-Yang Li, Michael F. A'Hearn, Michael J.S. Belton, Christopher J Crockett, Tony L. Farnham, Carey M. Lisse, Lucy A. McFadden, Karen J. Meech, Jessica M Sunshine, Peter C. Thomas, and Joe Veverka. 2007. Icarus 187, 41-55.

The Shape, Topography and Geology of Tempel 1 from Deep Impact Observations.

P. Thomas, J. Veverka, M.J.S. Belton, A. Hidy, M. A'Hearn, O. Groussin, C. Lisse, L. McFadden, J. Sunshine, D. Wellnitz, P. Schultz, K.J. Meech, W. A. Delamere. 2007. Icarus 187, 4-15.

Dust Coma Morphology in the Deep Impact Images of Comet 9P/Tempel 1.

T.L. Farnham, D.D. Wellnitz, D.L. Hampton, J.-Y. Li, J.M. Sunshine, O. Groussin, L.A. McFadden, C.J. Crockett, M.F. A'Hearn, M.J.S. Belton, P. Schultz, C.M. Lisse. 2007. Icarus 187, 26-40.

Deep Impact and Sample Return.

Michael F. A'Hearn, Michael J.S. Belton, Tony L. Farnham, Lori M. Feaga, Olivier Groussin, Carey M. Lisse, Karen J. Meech, Peter H. Schultz and Jessica Sunshine.  2006. Earth Planets Space, 58, 1-5.

Carbon Monoxide in Comet 9P/Tempel 1 before and after the Deep Impact Encounter.

P.D. Feldman, R.E. Lupu, S.R. McCandliss, H.A. Weaver, M.F. A'Hearn, M.J.S. Belton, and K.J. Meech.  2006. Astrophys. J. 647, L61-L64.

Hubble Space Telescope Observations of Comet 9P/Tempel 1 during the Deep Impact Encounter.

P.D. Feldman, S.R. McCandliss, M. Route, H.A. Weaver, M.F. A'Hearn, M.J.S. Belton, and K.J. Meech.  2007. Icarus 187, 113-122.

Photometric Analysis and Disk-resolved Thermal Modeling of Comet 19P/Borrelly from Deep Space 1 Data.

J-Y. Li, M.F. A'Hearn, L.A. McFadden and M.J.S. Belton.  2007.  Icarus 187, 41-55

The Spin State of 9P/Tempel 1.

M.J.S. Belton, P.C. Thomas, B. Carcich, C.J. Crockett, and the Deep Impact Science Team. 2006. 37th LPSC Abstract  #1487.       

Spitzer Spectral Observations of the Deep Impact Ejecta.

C.M. Lisse, J. VanCleve, A.C. Adams, M.F. A'Hearn, Y.R. Fernandez,  T.L. Farnham, L. Armus, C.J. Grillmair, J. Ingallis, M.J.S. Belton, O. Groussin, L.A. McFadden, K.J. Meech, P.H. Schultz, B.C. Clark, L.M. Feaga, and J.M. Sunshine. 2006. Science 313, 635-640.

Water Ice on the Surface of Comet Tempel 1.

J. M. Sunshine, M. F. A'Hearn, O. Groussin, J.-Y. Li, M. J. S. Belton, W. A. Delamere, J. Kissel, K. P. Klaasen, L. A. McFadden, K. J. Meech, H. J. Melosh, P. H. Schultz, P. C. Thomas, J. Veverka, D. K. Yeomans, I. Busko, M. Desnoyer, T. L. Farnham, L. M. Feaga, D. Hampton, D. Lindler, D. D. Wellnitz.  2006. Science 311, 1453-1455.

Rotation of Cometary Nuclei.  

N.H. Samarasinha, Beatrice E.A. Mueller, Michael J.S. Belton, and Laurent Jorda. Published in COMETS II (Eds. M.C Festou, H.U. Keller and H.A. Weaver) 2005, pp 281-299.

Deep Impact: Observations from a Worldwide Earth-based Campaign.

K.J. Meech and 210 co-authors (including M.J.S. Belton).  2005, Science 310, 265-269.

Deep Impact: Excavating Comet Tempel 1.

M. F. A'Hearn, M.J.S. Belton,  W. A. Delamere, J. Kissel, K. P. Klaasen, L. A. McFadden, K. J. Meech, H. J. Melosh, P. H. Schultz, J. M. Sunshine, P. Thomas, J. Veverka, D. K. Yeomans, M.W. Baca, I. Busko, C.J. Crockett, S. M. Collins, M. Desnoyer, C.A. Eberhardy, C.M. Ernst,  T. L. Farnham,  L. Feaga, O. Groussin, D. Hampton, S.I. Ipatov, J.-Y. Li, D. Lindler, C. M. Lisse,  N. Mastrodemos, W. M. Owen, Jr., J. E. Richardson, D. D. Wellnitz, R. L. White.  2005, Science 310, 258-264.

Rotationally Resolved 8-35 micron Spitzer Space Telescope Observations of the Nucleus of 9P/Tempel 1.

Lisse, C., A'Hearn, M.F., Groussin, O., Fernandez, Y.R., Belton, M.J.S., Van Cleve, J.E., Charmandaris, V., Meech, K.J., and McGleam, C.: 2005. Astrophys. J. 625, L139-L142.

Cometary Geology with Deep Impact Remote Sensing 
P.C. Thomas, J. Veverka, M.F. A'Hearn, L. McFadden, M.J.S. Belton, and J.M. Sunshine. 2005. Space Science Reviews, 117, 193-205.  
Deep Impact: A Large-Scale Active Experiment on a Cometary Nucleus 
M.F. A'Hearn, M.J.S. Belton, A. Delamere, and W.H. Blume. 2005. Space Science Reviews 117,1-21.  
Deep Impact: Working Properties for the Target Nucleus - Comet 9P/Tempel 1 
M.J.S. Belton, K.J. Meech, M.F. A'Hearn, O. Groussin, L. McFadden, C. Lisse, Y.R. Fernandez, J. Pittachova, H. Hsieh, J. Kissel, K. Klaasen, P. Lamy, D. Prialnik, J. Sunshine. P. Thomas, and I. Toth. 2005, Space Science Reviews, 117, 137-160. 
New Near-Aphelion Light Curves of Comet 2P/Encke.  
Y. R. Fernandez, S. C. Lowry, P. R. Weissman, B. E. A. Mueller, N. H. Samarasinha, M. J. S. Belton, and K. J. Meech.2005 Icarus, 175, 194-214. 
The Excited Spin State of Comet 2P/Encke.  
Michael J.S. Belton, Nalin H. Samarasinha, Yan R. Fernández, and Karen J. Meech. 2005 Icarus,175, 181-193. 
Mitigation of Hazardous Comets and Asteroids. (M.J.S. Belton, T.H. Morgan, N.H. Samarasinha and D.K. Yeomans, Eds)  
A book published by the Cambridge University Press in December, 2004, that includes a collection of invited papers given at the NASA Workshop on Scientific Requirements for Mitigation of Hazardous Comets and Asteroids.(see below)   
Exploration of the Solar System in the Coming Decade
Statement of Michael J.S. Belton before the U.S. Senate Committee on Commerce, Science, and Transportation. July 30, 2003.
A chapter for a new book Mitigation of Hazardous Comets and Asteroids (M.J.S. Belton, T.H. Morgan, N.H. Samarasinha and D.K. Yeomans, Eds). Published by Cambridge University Press in December, 2004 (see above).
An Open Letter to Gary L. Martin, NASA Space Architect.  
An April 2003 letter, signed by 30 space scientists, on important future goals for robotic and human spaceflight at NASA  following the Columbia tragedy. The letter emphasizes moving human activities out of LEO into near-Earth space and sets a goal to deflect a near-Earth asteroid. 
New Frontiers in the Solar System.  An Integrated Exploration Strategy
Report of the Solar System Exploration Survey (Chair, Michael J.S. Belton), Space Studies Board, National Research Council. July 9, 2002. Published by the National Academies Press ( in 2003. 
The Nucleus of Deep Impact Target Comet 9P/Tempel 1.  
Y.R. Fernandez, K.J. Meech, C.M. Lisse, M.F. A'Hearn, J. Pittichova, and M.J.S. Belton. Icarus, 165, 481-491 (2003). 
Interior of Small Bodies: Foundations and Perspectives.  
Richard P. Binzel, Michael AHearn, Erik Asphaug, M. Antonella Barucci, Michael Belton, Willy Benz, Alberto Cellino, Michel C. Festou, Marcello Fulchignoni, Alan W. Harris, Alessandro Rossi, Maria T. Zuber. Published in Planetary and Space Science, 51, 443-454 (2003).