Lunar Sample 61016, better known as "Big Muley", is alunar sample discovered and collected on theApollo 16 mission in 1972 in theDescartes Highlands, on the rim of Plum crater, nearFlag crater (Station 1). It is the largest sample returned from theMoon as part of theApollo program. The rock, an 11.7 kg (26 lb)breccia consisting mainly ofshockedanorthosite attached to a fragment oftroctolitic "melt rock", is named afterBill Muehlberger, the Apollo 16 field geology team leader.^[1][2]

Big Muley is currently stored at theLunar Sample Laboratory Facility at theLyndon B. Johnson Space Center.

Big Muley was discovered on the eastern rim ofPlum crater (Station 1) in the Descarteshighlands of the Moon.^[1] AstronautCharlie Duke said as he was picking up the sample, "If I fall into Plum crater getting this rock, Muehlberger has had it." In a 1996 letter and a 1997 e-mail message,^[3] Bill Muehlberger said:

Big Muley was a problem from the moment we saw it on TV(from theTV camera on theLRV). The crew had been told to pick up nothing larger than their fist – the lab types could analyze remarkably small pieces and get reproducible results. So, when we spotted Big Muley with the television camera and saw what looked like a large rectangle flashing at us, we jumped to the conclusion that it was a crystal – or cleavage – face ofplagioclasefeldspar. That made the rock ananorthosite which, according to our pre-mission interpretations, should not be present at this landing site. Further, there was a small crater on our side (between the Rover and Big Muley) that we thought could be a bounce crater caused by this rock on landing. The direction suggested that this could have been fromTheophilus, a large, relatively young crater that had been proposed as a source for some material that might be scattered across the landing area. So, I put in a request for the crew to pick it up as they returned to the LRV. We had no idea of size – it was the first sampling stop on the mission – but, once the crew got close, we realized that it was bigger than the max size suggested for return from the Moon and thenCharlie started complaining about it(s size) and about his struggle to pick it up. It turned out to be the largest rock returned from the Moon! And it turned out to be a useful rock for the researchers.

Big Muley is a 11.7 kg (26 lb)^[3]breccia, consisting mainly ofshockedanorthosite attached to a fragment oftroctolitic "melt rock".

The rock'scosmic ray exposure age was discovered to be about 1.8 million years, linking it to ejecta, or debris, from the impact that formedSouth Ray crater, to the south of the Apollo 16 landing site. Big Muley's age has been estimated since 1980 to be approximately 3.97 ± 0.25 billion years. The rock was highly shocked at some point in its history, as indicated by the fact that most of the rock'splagioclase content was converted tomaskelynite and/or plagioclaseglass.^[1]

• Great Scott
• Big Bertha
• List of individual rocks

• Lunar Sample 61016 — Images of Big Muley
• AS16-109-17789Archived 2014-10-02 at theWayback Machine — Big Muley is the large rock just above the end of the astronaut's shadow in this image

• Apollo 16
• Lunar samples
• John Young (astronaut)
• Charles Duke
• Pre-Nectarian

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