Thursday 11 September
Lunar comms architecture

Jim Schier
space comms and navigation office at NASA hq

Space comms and nav came out of LunarAechitectureTeam-2 study
Requirements include pervasive mobility, flexibility, global connectivity and long duration including outpost implemented to emulate Mars surface scenarios
Expect to require HD cameras and high bandwidth comms

Three architectures analysed for the Lunar Concept Review (LCCR), rapid outpost build up, inital mobility emphasis and initial habitation emphasis

Tenets for coms and nav are, functionally independent from other systems, extensible and open to add capability in future, interoperable, compatible with terrestrial communications and robust

Lunar Relay Satellite is basis for coms infrastructure, instead of TDRSS it will have fully onboard processed routed system

for surface, local wireless network.
Ka trunk back to Earth via LRS or Ka and S band between surface and LRS but will have otion to transmit back slowly direct to Earth

Early missions will have one LRS but future will require two

GPS quality timing signal will be sent to the lander

surface vehicles will periodically get a time and position calbration update from LRS but would use IMU, object recognition for its autonomus navigation

Mission concept review in 2010 for sortie support

Orbit option A for LRS is a 12h orbit, highly incined eccentric orbit gives about 8h of continuous coverage over one hemisphere or another
Option B is in orthogonal plane and gives more coverage

Done preliminary design on LRS, its solar powered, Ka/S band with 1m antenna, satellite is a third of the size of a TDRSS satellite

Three user types, fixed base, mobiler, EVA suit radio. Fixed has HDTV and voice and data capability, and other two less capability

All this was six months ago.

Now three things going on, commercial and international studies, International Lunar Network going on and spectrum and standards should evolve from ILN to exploration

Developing a plan for optical communications

Four nuclear powered landers, two arrive in 2013/14 and the second two 2016/17

LADEE will demo optical communications in 2011 timeframe

Optical com roadmap just develping wn, lunar optical comm by 20187 to Moon and Mars by 2023,

The development of optical comms includes a mobile transmitter linking with a synthetic aperture equipped orbital asset

Why opt for optical when it did not originally seem necessary?
When we look at it from a bigger pictrue we find out that for any kind of growth we rapidly run out of specturm if we want to push and scale the architecture, so that combined with the need for larger and complex missions and for deeper into the solar system it drives us to explore an optical network and test it on the Moon


Chirold Epp
Johnson Space Center
ALHAT programme manager

ALHAT is autonomous landing hazard avoidance technology

it is for both manned and robotic landers

we’re flying helicopters and airplanes not gantry or drop tests
no vacuum chamber yet, that is several years away

Apollo missions had landers land with nine to 11degree tilts

ALHAT is developing algorithms, developing autonomus flight manager, integrating GNC simulations

precision landing, one sigma error of less than 30m

we know there is going to be dust but if we think inertial systems can dead reckon yo down with accurate enough descent and timing information

ALHAT should be able to detect verticla heigh change fo 30cm, size of a basketball, and a slope of mroe than 5degrees

are thinking about what data to give to the crews during descent

using computers as close as possible to Altair

will use velocimetry for terminal phase of landing

star trackers being used as well

looking at flash LIDAR and spending some money developing flash LIDAR, to take a picture at points in descent and compare

put LIDAR doppler velocimetry on a helicopter and worked very well, think we can get accuracy of 2-3cm/s and detect velocity in all dirctions

TRN work with aircraft tests planned for spring 2009

field tests of flash LIDAR in May
helicoptetr flights over dry lakes at Dryden

Expect to have software, hardware system by 2012, all sensors and algorithms are still in development. Expect all of it to TRL6

In lunar landinf scenario, LIDAR should begin at a 1km, could be nicer to start at 1km
Used COTS 128×128 focal point array, went up to 500m and it worked well

LIDAR more compact and more accurate than RADAR altimeter