{{Short description|Valles on Mars}} {{Infobox feature on celestial object |name = Hebrus Valles |image = [[Image:Hebrus Valles.JPG|200px]] |caption = The Hebrus Valles, as seen by THEMIS. Direction of flow was determined by shape of streamlined islands. Terraces may reflect the occurrence of multiple flood events. |coordinates = {{coord|20.2|N|233.4|W|globe:mars_type:landmark|display=inline,title}} |location=[[Amenthes quadrangle]], Mars}} The '''Hebrus Valles''' are an ancient system of troughs and valleys in the [[Amenthes quadrangle]] of [[Mars]], located at 20.2° north latitude and 233.4° west longitude. They are 317 km long and were named after a [[Maritsa|river]] in the [[Balkans]] which runs through present day [[Bulgaria]], [[Greece]] and [[Turkey]]. Some authors have identified the troughs and valleys of Hebrus Valles as [[outflow channels]], but their origin and history remain ambiguous.<ref name=":0">Carr, M.H. (2006), ''The Surface of Mars''. Cambridge Planetary Science Series, Cambridge University Press.</ref> It has been considered as a potential site for human exploration due to the presence of icy caves.<ref name=":1">{{Cite journal|last1=Schulze-Makuch|first1=D.|last2=Davila|first2=A.|last3=Fairen|first3=A. G.|last4=Rodriguez|first4=A. P.|last5=Rask|first5=J.|last6=Zavaleta|first6=J.|date=2016-09-01|title=Ice Caves in Hebrus Valles: A Target Location for the First Human Mission to Mars|journal=Sixth International Conference on Mars Polar Science and Exploration |url=http://adsabs.harvard.edu/abs/2016LPICo1926.6014S|volume=1926|pages=6014|bibcode=2016LPICo1926.6014S }}</ref>
== Geology == The Hebrus Valles have [[tributary|tributaries]], terraces, and teardrop shaped islands. These features are all characteristic of erosion by fluid flow, but may or may not support the identification of this feature as carved by a single catastrophic outburst flood of water (as the term outflow channel would imply).<ref name=":0" /> The flood would have occurred during the early [[Amazonian (Mars)|Amazonian]].<ref>{{Cite journal|last1=Nerozzi|first1=S.|last2=Tober|first2=B.|last3=Holt|first3=J. W.|last4=Ortiz|first4=M.|date=December 2020|title=Reconstructing the geologic history of Hebrus Valles and Hephaestus Fossae, Mars with SHARAD|url=https://ui.adsabs.harvard.edu/abs/2020AGUFMP016.0004N/abstract|journal=AGU Fall Meeting Abstracts|language=en|volume=2020|pages=016–0004|bibcode=2020AGUFMP016.0004N }}</ref> There is also an extensive cave network which is expected to contain water ice.<ref name=":1" />
The Hebrus Valles region has been suggested to have Karst caves, which may be like the caverns of Earth. Such caves are formed by ancient water dissolving carbonate and sulfate rocks.<ref name=":2">{{Cite web |last= |first= |date=2025-11-16 |title=Scientists May Have Found Mars' First Water-Carved Caves — And They Could Be Hiding Life |url=https://www.sciencenewstoday.org/scientists-may-have-found-mars-first-water-carved-caves-and-they-could-be-hiding-life |access-date=2025-12-31 |website=Science News Today |language=en-US}}</ref> Researchers have found eight possible cave openings, or "skylights.”<ref name=":2" /> This discovery of water-carved caves is a significant finding because life may exist there since it would be protected from the harsh surface environment.<ref name=":3">{{Cite web |date=2025-11-26 |title=Ancient Life on Mars: Karstic Caves Hold Hidden Biosignatures - NASA Space News |url=https://nasaspacenews.com/2025/11/ancient-life-on-mars/ |access-date=2025-12-31 |language=en-US}}</ref> In addition, future colonists may be able to live in them.<ref name=":3" /> Karstic caves were formed when water flowed underground and dissolved carbonate and sulfate rocks, which created tunnels and chambers.<ref>{{Cite web |last=Mat |first=Mahmut |date=2024-10-31 |title=Karst Topography and Cave Formation » Geology Science |url=https://geologyscience.com/geology-branches/sedimentology/karst-topography-and-cave-formation/ |access-date=2025-12-31 |website=Geology Science |language=en-US}}</ref> When the roofs of these cavities collapsed, skylight entrances became visible from orbit.
The Thermal Emission Spectrometer (TES) discovered that the rock surrounding the cave entrances is rich in carbonates and sulfates, which easily dissolved by water. There is also much evidence that water flowed in the Hebrus Valles region, which contains tributaries, terraces, and teardrop-shaped islands that are formed by running water.<ref> {{Cite web |last=Alaieva |first=Liliia |date=2025-11-13 |title=Place of life: scientists find karstic caves on Mars |url=https://universemagazine.com/en/place-of-life-scientists-find-water-formed-caves-on-mars/ |access-date=2025-12-31 |website=Universe Space Tech |language=en-US}}</ref><ref> {{Cite journal |last1=Sharma |first1=Ravi |last2=Ding |first2=Chunyu |last3=Soldovieri |first3=Francesco |last4=Xu |first4=Jiangwan |last5=Liang |first5=Zihang |last6=Xie |first6=Yachen |last7=Su |first7=Yan |last8=Jiang |first8=Changzhi |last9=Zhi |first9=YuXiao |last10=Chuanhu |first10=Tang |last11=Qiu |first11=Xiaohang |last12=Lei |first12=Zhonghan |last13=Chen |first13=Haoyu |last14=Qingquan |first14=Li |date=2025-11-01 |title=Water-driven Accessible Potential Karstic Caves in Hebrus Valles, Mars: Implications for Subsurface Habitability |journal=The Astrophysical Journal Letters |volume=993 |issue=1 |pages=L36 |doi=10.3847/2041-8213/ae0f1c |doi-access=free |bibcode=2025ApJ...993L..36S |issn=2041-8205}} </ref>
== Gallery == <gallery class="center" widths="190px" heights="180px"> Image:Hebrus Valles from Themis.JPG|The Hebrus Valles, as seen from Themis. Since discontinuous pits and troughs are present, it is believed the troughs were created by collapse of surface material into voids. </gallery>
{{commons category|Hebrus Valles}}
==See also== * [[Amenthes quadrangle]] * [[Geology of Mars]] * [[Outflow channels]]
== References == {{reflist}}
{{Geography of Mars}} {{Portal bar|Solar System}}
[[Category:Valleys and canyons on Mars]] [[Category:Amenthes quadrangle]]