The British engineer has already been forced to climb outside his capsule once, as the balloon soared 9,000ft above the Mediterranean, to check for a fuel leak.
He used mountaineering equipment to climb on to the gondola roof yesterday and down an inspection ladder after the three-strong Breitling Orbiter 2 crew found that kerosene burner fuel had escaped from storage tanks.
However, a spokesman at the balloon's Flight Control Centre in Geneva revealed yesterday that the leak had not been plugged.
Don Cameron, whose Bristol-based company built the balloon, said that at the current rate of consumption the aircraft had enough fuel to stay afloat 10 days. He said progress had been "agonisingly slow" and that the balloon could take at least another day to reach the Suez Canal, where it should climb into the strong jetstream winds at around 27,000ft.
Although the balloon is supposed to have enough kerosene for 25 days it will only last about 10 if the leak is not fixed. "It is of some concern because they are using up fuel too quickly at the moment," Mr Cameron added.
"Andy may have to leave the gondola again to fix it. But we believe that if it is fixed and the winds pick up as they are forecast to do then there will not be a problem."
The balloon, currently drifting off the Italian coast at about 20mph, is scheduled to pass the Greek island of Corfu at lunchtime today. On Sunday it should then enter an airstream over Iraq, Turkey and Iran which will sweep it eastwards at about 75mph.
Elson, 44, of Wells, Somerset, is not said to be worried about the possibility of venturing outside again.
Speaking to ITN's chase plane, which is following the balloon, he said: "It is much nicer to be tied on with a bit of mountaineering equipment than it is to be holding on with your teeth."Reuse content