  LOFAR is the only radio telescope that is presently capable of
high-sensitivity, high-resolution (<1 mJy/b and <15") observations at ultra-low
frequencies (<100 MHz). To utilise these capabilities, the LOFAR Surveys Key
Science Project is undertaking a large survey to cover the entire northern sky
with Low Band Antenna (LBA) observations. The LOFAR LBA Sky Survey (LoLSS) aims
to cover the entire northern sky with 3170 pointings in the frequency range
42-66 MHz, at a resolution of 15 arcsec and at a sensitivity of 1 mJy/b. Here
we outline the survey strategy, the observational status, the current
calibration techniques, and briefly describe several scientific motivations. We
also describe the preliminary public data release. The preliminary images were
produced using a fully automated pipeline that aims to correct all
direction-independent effects in the data. Whilst the direction-dependent
effects, such as those from the ionosphere, are not yet corrected, the images
presented in this work are still 10 times more sensitive than previous surveys
available at these low frequencies. The preliminary data release covers 740
sqdeg around the HETDEX spring field region at a resolution of 47" with a
median noise level of 5 mJy/b. The images and the catalogue with 25,247 sources
are publicly released. We demonstrate that the system is capable of reaching an
rms noise of 1 mJy/b and the resolution of 15" once direction-dependent effects
are corrected for. LoLSS will provide the ultra-low-frequency information for
hundreds of thousands of radio sources, providing critical spectral information
and producing a unique dataset that can be used for a wide range of science
topics such as: the search for high redshift galaxies and quasars, the study of
the magnetosphere of exoplanets, and the detection of the oldest populations of
cosmic-rays in galaxies, clusters of galaxies, and from AGN activity.
