July 22, 2018 11:14 AM EDT

Buzz Aldrin, the second astronaut to walk on the moon, did not attend last night’s Apollo gala kicking off the year-long celebration of the 50th anniversary of the first time humans landed on the moon.

The 88-year-old Aldrin is normally a main attraction at the annual black tie event, and it was sponsored by the former NASA astronaut’s nonprofit foundation ShareSpace, which raises money to support STEM education and children’s interest in space exploration. Despite the event being promoted on his foundation’s website, Aldrin was a no-show at the Kennedy Space Center in Florida on Saturday night.

While no explanation was given for his absence at the event, it comes in the wake of a lawsuit he filed in June against two of his adult children, Andrew and Jan Aldrin, and his business manager Christina Korp. In the suit, Aldrin alleges elder exploitation and financial exploitation, accusing his sons of using his personal credit cards without his knowledge or consent and trying to take over the Buzz Aldrin brand, according to the Atlantic.

Both younger Aldrins denied the allegations in a letter to the Wall Street Journal, writing that they believe their father is being manipulated by his new managers, who formed a new company called Buzz Aldrin Ventures in April.

“Let it be clear that every one of these allegations are products of the increased confusion and memory loss that Dad has demonstrated in recent years… the responsibility for this outrageous lawsuit rests with those would seek to leverage his condition for their own agenda,” the letter states. Korp also denies the claims.

But Aldrin gave no sign that anything was wrong over the weekend, cheerfully tweeting about the event on Twitter Saturday.

At the gala Richard Branson, who founded the spaceflight company Virgin Galactic to take commercial flights into space, received ShareSpace’s Innovation Award. British physicist Brian Cox presented the billionaire entrepreneur with the award.

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