Spacewalk is a manual trick (usually performed by pressing left + right + flip trick while manualing) that slowly moves the skater forward. If walking is not included in THPS1+2, this trick is crucial in letting players who have completely stopped during a combo pick up enough speed to keep going. Otherwise, players who find themselves stopped will have to end their run.
Does this suggestion exist in THPS1/THPS2?
It was introduced in later games.