89

Because it's at the end of a 6 month cruise and there's no turning back. InSight will not enter closed orbit around Mars - its trajectory is hyperbolic so either it misses Mars entirely or it enters the atmosphere. There were six planned course corrections during the cruise phase, the final one of which - TCM 6 - occurred on the day of the landing. This ...


51

For a powered descent to the surface of a massive body like the Moon, it turns out to be most fuel efficient to do all your deceleration at the very end of the trajectory, right before impact. (This is because if you decelerate sooner than that, you will be in flight longer; the longer you're up, the more fuel you need to spend counteracting gravity ...


32

InSight doesn't enter Martian orbit before EDL; it plows straight into Mars' atmosphere from interplanetary space. Thus, the time of landing is pretty much un-alterable after its final midcourse correction maneuvers; it cannot wait for perfect weather conditions to land.


26

I'm pretty sure that by "soft good" he means it's an element of the system that can't be completely constrained from a simulation or engineering standpoint, in this case fabric. If you're working with static systems or systems with a limited amount of degrees of freedom, it's possible to calculate and analyse every possible state the system can be in. For ...


13

There are typically five planned trajectory correction maneuvers on the way to Mars, referred to as TCM-1 to TCM-5. (Also there is a slot for an emergency TCM-6 a few hours before entry, but it is not expected to be used.) Also I sometimes refer to launch as TCM-0. That's the really, really big TCM. TCM-0 provides the energy to place the aphelion of the ...


13

I'm pretty sure it will be like the Phoenix lander. Collectively that part of the lander is referred to as the "Backshell". This is the image of Phoenix of the hardware on the surface. This is mentioned in the official timeline. Powered Descent - Once the lander separates from its backshell and parachute, 12 descent engines on the lander begin firing and ...


11

When you're in orbit you have velocity roughly parallel to the atmosphere, a flat-ish shape angled properly can "fly" across it in a lifting entry where you can dissipate energy in the thinner upper atmosphere before you hit thicker atmosphere. The first stage of a rocket uses most of its energy to gain altitude, getting above the thickest part of the ...


11

During the parachute descent, InSight's trajectory is at an angle to the vertical. After the backshell and parachute separate, the engines fire, leveling the craft. This allows some horizontal separation between the parachute and the craft: 11:52 a.m. PST (2:52 p.m. EST) — Activation of the radar that will sense the distance to the ground 11:53 a.m....


10

It's called the "Kaktus-2". The sensor is referred to as a "NaI(TI) crystal detector" which appears to be a scintillation counter. The device has a 2 of 3 voting scheme to avoid false positives. "...the source emits 13.7 Sv/hr point blank at 1 cm, and 1.3 mSv/hr at one meter. That's quite hot :)" Here's a picture of the device. And here's a block ...


10

NASA is working on an inflatable heat shield. Not quite a blimp, but a heat shield that's inflatable to a size much larger than the probe it's attached to. The extra area helps decelerate the spacecraft. So inflatable structures can be made to withstand the heat of reentry. Because Mars' atmospheric density is only 0.6% of Earth's, a blimp's lift will ...


9

Surprisingly the answer is yes there was studies done on that subject. A simple google search could yield this result: BUOYANT PLANETARY ENTRY https://apps.dtic.mil/dtic/tr/fulltext/u2/642361.pdf In this study, it was assured that the large buoyant volune is deployed prior to atmospheric entry. The effect of buoyancy on the entry dynamics was ...


9

Unfortunately my answer won't contain the crucial "yes" or "no" - for the simple reason that one hinges upon fine parameters and would likely require a good NASA study for actual answer. But the answer I can give without that currently is "Quite likely so." 1) matter of sustaining the blimp in void. That one's easy "yes". If the blimp's envelope rated ...


8

You can use skip reentry to gradually reduce your speed when arriving from an interplanetary journey. NASA also studies skip reentry for the Shuttle, as a way to reduce the heat load during reentry. So you could use this technique to get below orbital speed before the final reentry starts. The lower your speed gets, the more difficult it will be to keep ...


8

To deal with dust storms, two of the changes between Phoenix and InSight are mechanical in nature: InSight uses a thicker heat shield, partly to handle the possibility of being sandblasted by a dust storm. InSight’s parachute suspension lines use stronger material. https://mars.nasa.gov/insight/timeline/landing/entry-descent-landing/ The ...


7

Context Mars density is less than 1% of earth's. This is what earth looks like from 30 000 meters high (where air is about as dense as Mars) It's going to be too heavy Using this book as a reference, we can see that to lift 1T to 30 000m we need a 10T balloon (accounting for balloon and lifting gazes). Of course you'll need more since you'll want to ...


7

Absolutely, it's the same as heating up metals with a blowtorch. The colour of the flame tells you what is present. Wikipedia actually has a handy list giving an indication of the significant elements present: Orange-yellow (sodium) Yellow (iron) Blue-green (magnesium) Violet (calcium) And Red (atmospheric nitrogen and oxygen)


6

The limiting case assumes a perfectly spherical moon and a lander that can do instantaneous burns of any magnitude. In this case, starting from a 110km circular orbit, the lander does a brief burn to drop periapsis to 0 altitude, then burns to cancel its entire surface-relative velocity all at once when it gets there. The initial burn is about 25 m/s; ...


5

Using a blimp for takeoff is pointless. The hard part of going to space is not the distance you travel to get out of the atmosphere. It is the speed. To get to space and stay there, you need to travel at 28,000 km/h. Once you have a vehicle capable of doing that, making it travel 200 km upwards is trivial. Using a balloon doesn't save fuel, it doesn't ...


5

Sometimes, and not as well as you are after. The problem here is that you don't understand the gravitational slingshot maneuver. In the reference frame of the planet there's no net velocity change. The spacecraft leaves with the same speed as it approaches, just on a different bearing. It is only in the reference frame of a larger body that you see a ...


5

Regarding your recent edit: No you can't just bounce around the atmosphere to slow down with a blimp. Unlike water, there is no clear limit between space and atmosphere, which leaves you with two options: Phase 1: You can decelerate at very high altitude where there is only faint trace of atmosphere => This will eventually decrease some (i.e. not nearly ...


5

Downrange is the distance traveled in the direction of flight. Imagine the orbit of a spacecraft as a circle around the Earth, 'downrange' is the distance traveled along this path. When you do a ballistic (uncontrolled) reentry, this is the path you travel. Crossrange comes into play when you make a turn, and you deviate from your orbit. It's the distance ...


5

I can't speak for Mercury or Gemini missions, but the Apollo parachute system is documented in NASA Technical Note D-7437, Apollo Experience Report: Earth Landing System. It appears that they designed the parachute system to reduce this phenomenon. Rotation of the spacecraft during descent is undesirable. It's a landing hazard, and it can cause motion ...


4

Yes, at least in theory, but in practice there is very little atmosphere on Mars, so your blimp will have to be huge, or the payload very small.


4

Curiosity actually had a camera recording when it descended at high enough of a rate to make a video of the decent on Mars.


4

Update: The QuickMap service is back up and completely overhauled. For this particular application, there is now a complete 3d model of the Moon that you can navigate freely, and it looks just awesome. To activate that option, click on the globe icon in the top left corner, and then click 'Lunar Globe 3D' in the pop-up menu. Navigation options and ...


4

InSight's landing on Mars was ballistic, see image below: Currently NASA has no plans to send humans to Mars besides vague notions of 2030s or 2040s however when NASA was working on the constellation program (that was subsequently cancelled) there were plans for Human to Mars missions. In 2009 the "Mars Design Reference Mission 5.0" was created. This ...


4

When a helicopter has an engine failure in flight, it goes into autorotation: as the helicopter loses altitude, the air moving up (relative to the rotor blades) drives the rotor blades to a usable speed. Just before hitting the ground, the pilot pulls up the collective pitch control to generate lift and slow the descent to a survivable landing. This must be ...


3

Partial answer, focusing on the landing legs only: The SpaceX solution where the fins contain the landing leg mechanism has two advantages over your solution: the landing legs are placed far apart and provide better stability, the landing legs are farther away from the engines, so they are heated less. The drawback is a heavy structure for the fins. ...


3

A typical rigid mid L/D aeroshell indicated in Mars exploration architecture encounters a maximum dynamic pressure of 11 kPa. While, Hypersonic Inflatable Aerodynamic Decelerator would encounter a maximum entry dynamic pressure of 4.24 kPa. Also, for mid L/D aeroshell based entry vehicles of Ares V kind, (Pg. 14) The aerodynamic model covers Mach 1.3 ...


3

While it would be hard to do, in part because of the very short time, and would be of questionable value, here is a concept for using MHD to do regenerative braking during Mars entry from the generated plasma.


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