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Author Topic: Landing updates from E-group  (Read 20130 times)
aftercolumbia
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« on: September 25, 2006, 01:50:05 PM »

We have a bunch of new posts over on the E-group at http://groups.yahoo.com/group/marsdirectproject

The big picture:

- Landing on Mars needs to be utterly overhauled for piloted missions. ┬ Using "standard" methods, the largest payload lander that can fit under a 5m fairing is about 1900kg; 8m, 5000kg; 10m, 7600kg and 12m, 11300kg. ┬ This has big implications for Mars Direct, but far larger ones for Mars For Less, which intends to use only 5m launch fairings.
- 14 August, aftercolumbia posted a "donut parachute" concept meant to be combined with a high beta, managed energy (L/D => 0.2) aeroshell. ┬ The intent of this (and paracones) is to reconfigure a lander from a high beta, low lift Soyuz-like configuration to a low beta, zero lift configuration emulating the Viking-like aeroshells used today. ┬ It has been tested in simulation with a zero lift, semi-aerocapture aeroshell, an a really big ringsail parachute and found to work well, although landing accuracy and element clearance leave something to be desired (Mark Paton ran the simulations.)
- NASA (mostly JPL) is working the problem at the concept level, and developing a "Mars EDL Mission Planner's Handbook" (perhaps not formally, but it is mentioned in the abstract and introduction of a paper about the results of parametric study of five major EDL variables.)

Internet Documents (abstracts here) regarding Mars EDL found so far:

http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38898/1/05-2473.pdf (recommended first read)

"There have been five fully successful robotic landings on Mars. The systems used to deliver these robots to the surface have shown large design diversity and continue to evolve. How will future Mars landing systems evolve to eventually deliver precious human cargo? We do not yet know the answers, but current trends tell us an interesting and daunting tale." - Rob Manning, Mark Adler (MER/Pathfinder EDL engineers)

http://pweb.ae.gatech.edu/labs/ssdl/Papers/Technical%20Papers/AAS%20GN&C%2006-072.pdf

"Near-term capabilities for robotic spacecraft include a target of landing
1 - 2 metric ton payloads with a precision of about 10 kilometers, at moderate
altitude landing sites (as high as +2 km MOLA). While challenging, these
capabilities are modest in comparison to the requirements for landing human
crews on Mars. Human Mars exploration studies imply the capability to safely
land 40 - 80 metric ton payloads with a precision of tens of meters, possibly at
even higher altitudes. New entry, descent and landing challenges imposed by the
large mass requirements of human Mars exploration include: (1) the potential
need for aerocapture prior to entry, descent and landing and associated thermal
protection strategies, (2) large aeroshell diameter requirements, (3) severe mass
fraction restrictions, (4) rapid transition from the hypersonic entry mode to a
descent and landing configuration, (5) the need for supersonic propulsion
initiation, and (6) increased system reliability. This investigation explores the
potential of extending robotic entry, descent and landing architectures to human
missions and highlights the challenges of landing large payloads on the surface
of Mars." - G. Wells et. al. (Georgia Tech)

http://www.ae.gatech.edu/labs/ssdl/Papers/Masters/AE%208900%20Report%20(no%20appendix).pdf

"The purpose of this investigation is to begin forming a dataset to be the basis of a Mars
entry, descent and landing mission design handbook for planetary probes. The premise of
the project is that Mars entry, descent and landing can be parameterized with five variables:
(1) entry mass, (2) entry velocity, (3) entry flight path angle, (4) vehicle aeroshell diameter,
and (5) vertical lift-to-drag ratio. For combinations of these input parameters, the following
trajectory information will be determined: peak deceleration, peak heat rate, heat load, and
the altitude at which Mach 2 is reached (for parachute deployment)." - Grant Wells (Georgia Tech)

http://engineering.kingston.ac.uk/space/research/papers/elieallouis/IAF03-EDLS-Allouis.pdf

Vanguard is a proposed post-Beagle2 mission to
Mars focussed on astrobiology, but also on
technology demonstration[1]. The 120 kg probe is
assumed to use a Mars-Express- type bus to land a
triad of robotics comprising a lander, a rover and 3
penetrating moles. The landed mass is around 65
kg. The mission is baselined to be low-cost with
limited power and mass requirements to be
accommodated as a secondary payload on a future
mission to Mars[2]. Here the Entry, Descent and
Landing system (EDLS) is investigated comparing
conventional methods (hard heatshield/Parachute)
to current new developments in inflatable entry
structures as demonstrated by missions such as
IRDT and IRDT2. Two systems are designed to
provide an understanding of EDLS requirements in
term of masses and volumes to land a small probe
safely on Mars. Preliminary results[3] show that,
despite the heritage, a conventional approach is
heavier than inflatable technologies. Indeed, in this
particular case, a margin of about 15 % is derived
in favour of the inflatable system. For a constantmass
probe, this means that the mass is saved from
the EDLS to the benefit of the payload. Moreover,
despite having a larger range, and longer descent, in
this case the inflatable option has in this case a
wind gust sensitivity comparable to the parachute
option." - Ellie Allouis, Alex Ellery, Chris Welch (Kingston University (UK), School of Engineering)

Note: "Inflatable Structure" means donut chute; obviously aftercolumbia was not the first to think of it.

http://www.sra.org/docs/Paulos.pdf

"RISK ASSESSMENT APPLICATIONS TO
SCIENCE AND EXPLORATION MISSIONS" - Dr. Todd Paulos, Netcom

Note: This is a projector presentation.

Something crashed, hitting send so I don't lose this


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kingtim
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To infinity... and beyond!

skatintim3704559
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« Reply #1 on: March 30, 2010, 11:36:46 AM »

Really interesting post!

How difficult is it for these missions to change gears? Do they have solid control to alter their own actions or does Nasa, to put it in the common mans language, have to "talk to corporate".


I have wondered for a long time about the political side of the Nasa program.
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