download public data

ascp -QT -l 640M -i ~/.aspera/connect/etc/asperaweb_id_dsa.openssh  \
anonftp@ftp-trace.ncbi.nlm.nih.gov:/sra/sra-instant/reads/ByStudy/sra/SRP/SRP046/SRP046745 .

See documentation here. The only note I would add is that if you’re asked to supply a password using their public openssh key you’re doing something wrong; it’s probably a typo.