Free Astronomy Magazine September-October 2023 ARABIC VERSION

T 21 servations by Hubble also give an estimate for the size of the DART impact crater, Hera will eventually determine the actual crater size. Long ago, Dimorphos may have formed from material shed into space by the larger as- teroid Didymos. The parent body may have spun up too quickly or could have lost material after a glancing colli- sion with another ob- ject, among other scenarios. The ejected material formed a ring that gravitationally co- alesced to form Dimor- phos. This would make it a flying rubble pile of rocky debris loosely held together by the relatively weak pull of its gravity. Therefore, the interior is probably not solid, but has a structure more like a bunch of grapes. It’s not clear how the boulders were lifted off the asteroid’s surface. They could be part of an ejecta plume that was photographed by Hubble and other ob- servatories. Or a seismic wave from the impact may have rattled through the asteroid — tailed post-impact survey of the tar- get asteroid Dimorphos. Hera will turn the grand-scale experiment into a well-understood and repeat- able planetary defence technique that might one day be used for real. The boulders are most likely not shattered pieces of the diminutive asteroid caused by the impact. They were already scattered across the as- teroid’s surface, as evident in the last close-up picture taken by the DART spacecraft just two seconds before collision, when it was only 11 kilo- metres above the surface. The science team that observed these boulders with Hubble esti- mates that the impact shook off two percent of the boulders on the aster- oid’s surface. While the boulder ob- like hitting a bell with a hammer — shaking loose the surface rubble. The DART and LICIACube (Light Ital- ian CubeSat for Imaging of Aster- oids) teams have also been studying boulders detected in images taken by LICIACube’s LUKE (LICIACube Unit Key Explorer) camera in the minutes immediately following DART’s kinetic impact.      21 ﺗﻢ اﻟﺘﻘﺎط ﻫﺬﻩ اﻟﺼﻮرة ﺑﻮاﺳـﻄﺔ ﺗﻠﺴـ ﻮب ﻫﺎﺑـﻞ اﻟﻔﻀــﺎﺋﻲ ﻟﻠ ﻮ ﻜــﺐ د ﻤﻮرﻓــﻮسﻓــﻲ 19 د ﺴـــﻤ 2022 أي ﻌـــﺪ ﻣــــﺎ ﻘـــﺮ ﻣــــﻦ أرﻌﺔ أﺷﻬﺮﻣﻦ اﺻﻄﺪام اﻟ ﻮ ﻜﺐ ﻤﻬﻤـﺔ اﻟﻤﺴـــــ ﺎر ) ( دارات ) ــــــﮫ ـــــﺎرإﻋـــــﺎدة ﺗﻮﺟ اﺧﺘ اﻟ ﻮ ﻜــــﺐ اﻟﻤــــﺰدوج ( اﻟﺘﺎ ﻌــــﺔ ﻟ ﻮ ﺎﻟــــﺔ ﻧﺎﺳـــــﺎ . وﺗﻜﺸﻒ ﺣﺴﺎﺳ ﺔ ﺗﻠﺴ ﻮب ﻫﺎﺑﻞ ﻋـﻦ ﻀـﻊ اﺻـــــــــــﻄﺪﻣﺖ ﻋﺸــــــــــﺮات ﻣــــــــــﻦ اﻟﺼـــــــــــﺨﻮر اﻟــــــــــ ﺎﻟ ﻮ ﻜــﺐ ﻘــﻮة اﻻﺻــﻄﺪام . ﻫــﺬﻩ ﻫــﻲﻣــﻦ ﺻـــــﻮرﻫﺎ ﻫﺎﺑـــــﻞ أﺿـــــﻌﻒ اﻷﺟﺴـــــﺎم اﻟـــــ ﺑـــــ ﻋﻠـــــﻰ اﻹﻃـــــﻼق داﺧـــــﻞ اﻟﻨﻈـــــﺎم اﻟﺸﻤﺴــــــﻲ . ـــﻢ اﻟﺼـــﺨﻮر اﻟﻤﻘﺬوﻓــﺔ ﻣـــﻦ ﻣـــ ــ اوح ﺣ و واﺣــــــﺪ إﻟــــــﻰ 6.7 ﻣــــــ ــــــﺎس اﺳــــــﺘﻨﺎدا إﻟــــــﻰﻗ ﺗﻠﺴــــــــ ﻮب ﻫﺎﺑــــــــﻞ اﻟﻀــــــــﻮﺋﻲ . ﺗﻠــــــــﻚ اﻟﺼــــــــﺨﻮر ﺗﻨﺠــﺮف ـــﺪ اً ﻌ ﻋــﻦ اﻟ ﻮ ﻜـــﺐ ﺴــﺮﻋﺔ ﺣـــﻮاﻟﻲ ﻛ ﻠـــــــــــﻮﻣ ﻓــــــــــــﻲ اﻟﺴــــــــــــﺎﻋﺔ ﻫــــــــــــﺬا وﻳــــــــــــﺆد ــــــﺜﻤﻦ ﺣــــــﻮل اﻻﻛﺘﺸــــــﺎف إﻟــــــﻰ رؤىﻻ ﺗﻘــــــﺪر ﺳـــــــــﻠﻮك ﻮ ﻜـــــــــﺐﺻـــــــــﻐ ﻋﻨـــــــــﺪﻣﺎ ﺼـــــــــﻄﺪم ﻘﺬ ﻔﺔ ﻐﺮضﺗﻐﻴ ﻣﺴﺎرﻩ . ] NASA, ESA, D. Jewitt (UCL [ إﻃﻼﻗﻬﺎ ﰲ ﻋـﺎم 2024 وﺳـﺘﺠﺮي ا ﺮﻛﺒـﺔ اﻟﻔﻀﺎﺋﻴﺔ ﻣﺴﺤ ﺎً ﺗﻔﺼﻴﻠﻴ ﺎً ﺑﻌـﺪ اﻻﺻـﻄﺪام ﺑﺎ ﻟﻜﻮﻳﻜﺐ ا ﺴﺘﻬﺪف دﻳﻤﻮرﻓـﻮس . ﺳـﻮف ﻳﻘـﻮم ا ﺴـﺒﺎر ( ﻫـ ا ) ﺑﺘﺤﻮﻳـﻞ اﻟﺘﺠﺮﺑـﺔ واﺳﻌﺔ اﻟﻨﻄﺎق إﱃ ﺗﻘﻨﻴﺔ دﻓﺎﻋﻴـﺔ ﻛﻮﻛﺒ ﻴـﺔ ﻣﻔﻬﻮﻣﺔ ﺟﻴﺪاً وﻗﺎﺑﻠـﺔ ﻟﻠﺘﻜـﺮار واﻟﺘـﻲ ﻗـﺪ ﺗُﺴﺘﺨﺪم ﻳﻮﻣـﺎً ﻣـﺎ ﺑﺸـﻜﻞ ﺣﻘﻴﻘـﻲ . ﻣـﻦ ا ﺮﺟﺢ أن اﻟﺼﺨﻮر ﻟﻴﺴﺖ ﻗﻄﻌًﺎ ﻣﺤﻄﻤـﺔ ﻣﻦ اﻟﻜﻮﻳﻜﺐ اﻟﻀﺌﻴﻞ اﻟﻨﺎﺗﺞ ﻋﻦ اﻻﺻﻄﺪام . ﻣ ـﻦ اﻟ ﻜﻮﻳﻜــﺐ اﻟﺼ ـﻐ او ﻧﺎﺗﺠ ـ ﺔ ﻋ ـﻦ اﻻﺻﻄﺪام وﻛﺎﻧـﺖ ﻣﺘﻨـﺎﺛﺮة ﺑﺎﻟﻔﻌـﻞ ﻋـﲆ ﺳﻄﺢ اﻟﻜﻮﻳﻜﺐ ﻛﻤـﺎ ﻫـﻮ واﺿـﺢ ﰲ آﺧـﺮ ﺻﻮرة ﻗﺮﻳﺒﺔ اﻟﺘﻘﻄﺘﻬﺎ ا ﺮﻛﺒﺔ ( دارت) ﻗﺒﻞ ﺛﺎﻧﻴﺘ ﻓﻘﻂ ﻣﻦ اﻻﺻﻄﺪام ﻋﻨـﺪﻣﺎ ﻛﺎﻧـﺖ ﻋﲆ ارﺗﻔﺎع 11 ﻴﻠﻮﻣﱰ ﻛ اً ﻓﻘﻂ ﻓﻮق اﻟﺴﻄﺢ . ﻳﻘـﺪر اﻟﻔﺮﻳـﻖ اﻟﻌﻠﻤـﻲ اﻟـﺬي رﺻـﺪ ﻫـﺬه اﻟﺼﺨﻮر ﺑﺎﺳﺘﺨﺪام ﻫﺎﺑﻞ أن اﻻﺻﻄﺪام ﻫﺰ ﺳﻴﺤﺪد ﰲ اﻟﻨﻬﺎﻳﺔ ﺣﺠﻢ اﻟﺤﻔﺮة اﻟﻔﻌﲇ . 2 % ﻣﻦ اﻟﺼـﺨﻮر ا ﻮﺟـﻮدة ﻋﲆ ﺳﻄﺢ اﻟﻜﻮﻳﻜﺐ ﰲ ﺣ أن أرﺻـﺎد ﺗﻠﺴـﻜﻮب ﻫﺎﺑـﻞ ﻟﻠﺼﺨﻮر ﺗﻌﻄﻲ أﻳﻀ ﺎً اً ﺗﻘﺪﻳﺮ ﻟﺤﺠﻢ اﻟ ﻔﻮﻫﺔ اﻟﻨﺎﺗﺠـﺔ ﻋـﻦ ارﺗﻄﺎم ا ﺮﻛﺒﺔ ( دارت) ﻓـﺈن ا ﺴﺒﺎر ﺳﻮف ( ﻫ ا ) ﻳﺤـﺪد ﰲ اﻟﻨﻬﺎﻳ ـﺔ ﺣﺠ ـﻢ اﻟﻔﻮﻫــﺔ اﻟﻔﻌﲇ . ﻣﻨﺬ ﻓﱰة ﻃﻮﻳﻠﺔ رﺑﻤﺎ ﻳ ﻜـﻮن اﻟ ﻜﻮﻳﻜـﺐ دﻳﻤﻮرﻓـﻮس ﻗـﺪ ﺗﺸﻜﻞ ﻣﻦ ﻣﺎدة اﻧﻄﻠﻘـﺖ إﱃ اﻟﻔﻀﺎء ﻣﻦ اﻟﻜﻮﻳﻜﺐ اﻷﻛـﱪ ﺣﺠﻤﺎً دﻳﺪﻳﻤﻮس رﺑﻤﺎ ﻳﻜﻮن اﻟﺠﺴﻢ اﻷﺻـﲇ ﻗـﺪ اﻧﻄﻠـﻖ ﺑﴪﻋﺔ ﻛﺒ ة ﺟـﺪ اً أو رﺑﻤـﺎ ا ـ ﺪ ﻓﻘـ ﻮاد ﺑﻌـﺪ اﺻـﻄﺪام ﺧﺎﻃﻒ ﺑﺠﺴﻢ آﺧﺮ ﻣﻦ ﺑـ ﺳﻴﻨﺎرﻳﻮﻫﺎت أ ىﺧﺮ وﺷﻜﻠﺖ ا ــﺎدة ا ﻘﺬوﻓ ــﺔ ﺣﻠﻘ ــﺔ اﻧ ـﺪﻣ ﺠﺖ ﺑﻔﻌ ـﻞ اﻟﺠﺎذﺑﻴ ـﺔ ﻟﺘﺸﻜﻞ دﻳﻤﻮرﻓﻮس وﻫﺬا ﻣﻦ ﺷــﺄﻧﻪ أن ﻳﺠﻌﻠﻬــﺎ ﻛﻮﻣــﺔ أﻧﻘﺎضﻣﺘﻄﺎﻳﺮة ﻣﻦ اﻟﺤﻄﺎم اﻟﺼـﺨﺮي ﻣﺘﻤﺎﺳـﻜﺔ ﻣﻌ ـﺎً ﺑﺸﻜﻞ ﻏ ﻣ ﺤﻜﻢ ﺑﺴﺒﺐ ﻗﻮة اﻟﺠــﺬب اﻟﻀــﻌﻴﻔﺔ ﻧﺴــﺒﻴ ﺎً ﻟﺠﺎذﺑﻴﺘﻬﺎ ﻟﺬﻟﻚ رﺑﻤﺎ ﻻ ﻳﻜﻮن اﻟﺠﺰء اﻟﺪاﺧﲇ ﺻﻠﺒ ﺎً وﻟﻜﻦ ﻟﻪ ﻫﻴﻜﻞ ﻳﺸﺒﻪ ﻋﻨﻘﻮد اﻟﻌﻨـﺐ . ﻟﻴﺲ ﻣﻦ اﻟﻮاﺿﺢ ﻛﻴـﻒ ﺗـﻢ رﻓﻊ اﻟﺼـﺨﻮر ﻣـﻦ ﺳـﻄﺢ رﻓﻊ اﻟﺼﺨﻮر ﻣﻦ ﺳﻄﺢ اﻟﻜﻮﻳﻜﺐ ﻴﻤﻜﻦ ﻓـ أن ﺗﻜﻮن ﺟﺰء اً ﺎً ﻣﻘﺬوﻓ أو ﻗﺪ ﺗﻜﻮن ﻣﻮﺟـﺔ زﻟﺰاﻟﻴﺔ ﻧﺎﺟﻤﺔ ﻋﻦ اﻻﺻـﻄﺪام ﻣﻤـﺎ أدى إﱃ ﺗﻔﻜﻚ اﻟﺮﻛﺎم اﻟﺴﻄﺤﻲ . ﻗﺎم ﻓﺮﻳﻖ ا ﺮﻛﺒـﺔ ( تدار ) أﻳﻀـﺎً ﺑﺪراﺳـﺔ اﻟﺼــﺨﻮر ﰲ اﻟﺼــﻮر ا ﻠﺘﻘﻄ ـﺔ ﺑﻮاﺳ ـﻄﺔ ا ) ﺮﻛﺒﺔ ﻟﻴﺴﻴﺎ ﻛﻴﻮب ( اﻻﻳﻄﺎﻟﻴﺔ ﰲ اﻟـﺪﻗﺎﺋﻖ اﻟﺘﺎﻟﻴﺔ ﻣﺒﺎﴍة ﺑﻌﺪ ﻋﻤﻠﻴﺔ اﻻﺻﻄﺪام . - ﺳﺒﺘﻤﺒﺮ ﺃﻛﺘﻮﺑﺮ 2 0 2 3