Near-Earth asteroid ( 3200 ) Phaethon is notable for its association to a strong annual meteor shower , the Geminids , indicative of one or more episodes of mass ejection in the past .
The mechanism of Phaethon ’ s past activity is not yet understood .
Here we present a Hubble Space Telescope ( HST ) search of meter-sized fragments in the vicinity of Phaethon , carried out during Phaethon ’ s historic approach to the Earth in mid-December of 2017 .
Numerical simulation conducted to guide HST ’ s pointing also show that the dynamical evolution of Phaethon-originated particles is quick , as ejected materials take no longer than \sim 250 yr to spread to the entire orbit of Phaethon .
Our search was completed down to 4-meter-class limit ( assuming Phaethon-like albedo ) and was expected to detect 0.035 % particles ejected by Phaethon in the last several decades .
The negative result of our search capped the total mass loss of Phaethon over the past few dozen orbits to be 10 ^ { 12 } kg at 3 \sigma level , taking the best estimates of size power-law from meteor observations and spacecraft data .
Our result also implies a millimeter-sized dust flux of < 10 ^ { -12 } ~ { } \mathrm { m ^ { -2 } ~ { } s ^ { -1 } } within 0.1 au of Phaethon , suggesting that any Phaethon-bound mission is unlikely to encounter dense dust clouds .