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#1 2012-02-23 22:14:25

sanman
Banned
Registered: 2012-02-23
Posts: 27

Question - What's the Smallest Re-Entry Vehicle Possible?

Hi everyone,

I have a question - what's the smallest unmanned entry vehicle possible for descent from Martian orbit to the surface using an aeroshield and parachute?
What kind of mass and dimensions would be feasible for a minimal payload?
Do you think 10cm wide is too small? How about 5cm wide?
5 kg? 2 kg?

What's the smallest you can go, before weird problems of slipstream turbulence and cross-winds cause too much difficulty in targeting a landing zone?
The landing zone I was thinking of was a fairly large one - the Hellas Basin - and so I'd imagine it wouldn't be too hard to hit from a polar orbit.

The payload merely has to be able to measure ambient atmospheric pressure and water humidity on the surface in Hellas Basin.

Any useful feedback is appreciated.

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#2 2012-02-24 19:54:14

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,750

Re: Question - What's the Smallest Re-Entry Vehicle Possible?

I was wondering the same thing over on the MarsDrive site with regards to launching a cube sat plus landing apperatus to make it land safely.

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#3 2012-06-11 22:19:02

JonClarke
Member
From: Canberra, Australia
Registered: 2005-07-08
Posts: 173

Re: Question - What's the Smallest Re-Entry Vehicle Possible?

The Deep Space 2 probes massed 2.4 kg.  Although they failed they show that it is possible to have an interesting and useful minimal surface mission in the nanosat class http://en.wikipedia.org/wiki/Deep_Space_2

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#4 2012-06-12 02:21:50

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Question - What's the Smallest Re-Entry Vehicle Possible?

JonClarke wrote:

The Deep Space 2 probes massed 2.4 kg.  Although they failed they show that it is possible to have an interesting and useful minimal surface mission in the nanosat class http://en.wikipedia.org/wiki/Deep_Space_2

But haven't we got Mars satellites in orbit? I imagine small devices would be able to speak to the satellites that then relay info back to Earth.

The smaller the load, the more impact it can sustain I would imagine e.g. if you have a 2 kg wrapped up in 3 kgs of sophisticated wadding. Or can you do a last minute mini launch before you hit the surface, so landing speed is really slow.


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#5 2012-06-12 07:39:27

Rune
Banned
From: Madrid, Spain
Registered: 2008-05-22
Posts: 191

Re: Question - What's the Smallest Re-Entry Vehicle Possible?

The smaller you go, the better your ballistic coefficient you get, so lower terminal velocity. Make it feather-like, and you need no parachute. A few grams of carbon fiber with a few tens of centimeters of diameter would land pretty softly on their own. So no lower boundary, a penny-sized piece of carbon-carbon would land much easier than MSL.

What could you do with that, now that's another question (my answer is very little, since a comm system capable of reaching orbit is too heavy to fit, never mind sensors). But a paper plane can theoretically survive earth reentry if the paper can survive the thermosphere.


Rune. They tried that from ISS, actually, though I heard no more about it.


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#6 2012-06-12 23:30:22

JonClarke
Member
From: Canberra, Australia
Registered: 2005-07-08
Posts: 173

Re: Question - What's the Smallest Re-Entry Vehicle Possible?

louis wrote:

But haven't we got Mars satellites in orbit? I imagine small devices would be able to speak to the satellites that then relay info back to Earth.

The smaller the load, the more impact it can sustain I would imagine e.g. if you have a 2 kg wrapped up in 3 kgs of sophisticated wadding. Or can you do a last minute mini launch before you hit the surface, so landing speed is really slow.

You might not want it to be slow - the DS-2 probes were penetrators after all.

Not sure whether the were meant to communicate directly to Earth or via a relay.  Relay would be easier, I would have thought.  There was MGS already in orbit and of course MCO was supposed to be there as well.

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#7 2013-12-07 17:49:39

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 28,750

Re: Question - What's the Smallest Re-Entry Vehicle Possible?

There has been quite a few cubesats launched and here is another that is quite interesting.

NASA's smartphone cubesat launched from MARS last month phones home

The mini satellite literally uses a smartphone as a brain, encased in a cube 4 inches square weighing a mere 2 pounds. It’s part of NASA’s long-range mission to see how well off-the-shelf commercial components perform in space, allowing the space agency to launch satellites at a fraction of the previous cost.

PhoneSat 2.4 is the first of its kind to use a two-way S-band radio, NASA says, allowing engineers to command the satellite from Earth.

http://spaceref.com/nasa-hack-space/sma … -home.html

oophonesat202_1.jpg

Last edited by SpaceNut (2013-12-07 18:19:56)

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