New Mars Forums

Cheers cIclops,

Here is a nice sequence from the same event.

Earthrise over lunar south pole Saturday 5th April 2008.

Andrew Brown.

Hi Vincent.

25143 Itokawa surface gravity: 0.0001 ms/2.
Earth surface gravity: 9.7803 ms/2.

0.0001 / 9.7803 = 1/102,246. So Earth's surface gravity is approx 102,246 times stronger that of 25143 Itokawa's.

Earth escape velocity: 11.186 KPS or 40,269 KPH.
25143 Itokawa escape velocity: 0.0002 KPS or 0.72 KPH.

So in other words, a landing on 25143 Itokawa, would be more like a docking.

Hope that helps.

Andrew Brown.

I agree cIclops, when MESSENGER finally arrives in Hermeocentric orbit in March 2011, so much will be learnt.

The upcoming encounter this October, will show practically the rest of the unimaged terrain, on the inbound leg & a large slice of preimaged terrain from Mariner 10 will be seen outbound, though the Sun will be shining from the opposite direction.

The only real gripe I have with the mission, is the orbit used in the orbital mission. IMO it would have been best had the orbit been a low polar one, but instead, it is elliptical, with much of the equator & the southern hemisphere not being seen at as high resolution as much of the northern hemisphere.

MESSENGER is a beautifully built, superbly engineered spacecraft (no complaints about the MESSENGER spacecraft at all though), but I fear, will not be used to the best of its abilities.

I hope NASA / JHU decide to change the Hermeocentric orbit in the primary mission.

Mercury is far more fascinating than is given credit for.

Last week's update was very interesting.

Northern Beagle Rupes. 250 KM wide area shown.

The 170 KM wide lava filled crater at the top of the image is also very interesting.

Andrew Brown.

MRO SHARAD penetrates Martian South Polar Cap.

Comparisons between MRO SHARAD & MEX MARSIS, revealing how the two complement each other, MEX Marsis was able to penetrate very deep, approx 3,700 metres, where as MRO SHARAD shows a higher resolution in the structure nearer the surface.

Animation.

Andrew Brown.

Hi noosfractal & cIclops.

On Thursday 11th January 2007, when MRO HiRISE imaged Jupiter during opposition on that date, Jupiter was blazing away at magnitude -2.65, just north of the star Lambda Librae.

The Earth reached magnitude -2.08 on Saturday 15th September 2007, when the Earth reached greatest eastern elongation & blazed in the evening skies of Mars. Our Moon was magnitude +3.00, approx 15' away to the west.

The Earth appeared in front of Ophiuchus on that date, the Sun in front of Libra.

Earth & Moon if viewed through a telescope from the surface of Mars would have appeared as a pair of half phases.

Not too unlike:
the MGS Earth / Moon shot from Mars orbit.

The MGS MOC observations of Earth & Jupiter from Mars Orbit was incredible, a very close conjuction in Cancer as seen from Mars.

Andrew Brown.

Absolutely Commodore. I suggested HiRISE Phobos & Deimos observations in the HiRISE HiBlog & email a while back. I know that I was not alone, but a good case was made.

I have also suggested that the observations be repeated when Mars is at a different point in its Heliocentric orbit, so the illumination is at a differnet angle (obviously not when Phobos is at New Phase as pointing HiRISE in the direction of the Sun would be very stupid & foolish).

Perhaps these observations will help determine the origin of Phobos & Deimos. I still recko they are captured type D asteroids, more typical of the asteroids in the outer part of the Asteroid Belt.

Also maybe very similar to some of Jupiter's outermost moons in the retrograde family like Pasiphae, Sinope, Carme, Anake, Erinome, etc?

I hope HiRISE does get to do Deimos too.

MRO HiRISE of Phobos.

MRO HiRISE of the Marsshine on the night side of Phobos.

Andrew Brown.

Hi Vincent. Your image is not far from the one I posted, within the same landing ellipse but I think slightly further north than the one I posted.

Yes Phoenix is landing in Late May, late Spring on Earth, so lets see.

This time the Martian Northern Summer Soltice is on Tuesday 24th June 2008, only three days after the same event on Earth (spooky uh).

So Phoenix will be arriving at the terrestrial equivalent of early June or early Summer.

The Martian Northern Autumn Equinox will be on Sunday 10th January 2009.

The Phoenix Primary Mission will take Phoenix roughly to the Martian Summer Cross Quarter point, roughly half way between the Summer Solstice & Autumn Equinox, or roughly the terrestrial equivalent of 2nd / 3rd August. I really hope Phoenix makes it all the way to at least mid January, past the Martian Equinox.

So in short, the Phoenix Primary Mission begins just before the Martian Northern Summer Solstice, to roughly half way to the Autumn Equinox.

Hope that helps?

My name is also on Phoenix & I was also involved in the campaign to get the mission approved (also DAWN & New Horizons).

BTW I like that cartoon you linked too. I have put the same link on Space.com & The Spaceport. 

Andrew Brown.

You are not wrong there cIclops.

Cassini is worth every cent & more.

It is tremendous news that Cassini has been extended a minimum of two years.

This is fantastic news. We get to see the Saturn Equinox in December 2009 (Titan's August 2009).

Great news, I had heard of some of what's planned & hope at least some of those 26 passes of Titan are Sythetic Aperture Radar imaging passes.

The seven passes of Enceladus will be interesting, as the Tiger Stripes move into the night. We'll see if the activity continues after the Sun sets. If it does not, it will prove that the geysers are solar powered, if it does, than definately internally driven or tidal.

Great to see Dione on the manifest, also one of Saturn's most interesting & picturesque moons & may not be totally inert, with quite a wide range of surface features & a very interesting history.

The first really close pass of a co-orbital, Helene, Dione's leading Trojan. Helene, Dione's leading co-orbital moon. A small moon with dimensions of 36 KM x 32 KM x 30 KM. This will be the closest scientific pass of a minor Saturn moon since Phoebe in June 2004. Helene below. Irregularly shaped & cratered.

Rhea gets a second very close pass, hopefully shedding light as to why 1,528 KM wide Rhea remained so unevolved, despite it's fairly large size (probably fairly low density has something to do with it).

Shame Cassini cannot revisit Iapetus, but the extension is fascinating none the less.

We'll get to see Saturn itself change seasons, will be interesting to see if after December 2009, the southern polar region of Saturn starts turning blue, as the north polar region has been?

All in all, fantastic news.

Andrew Brown.

Hi ciclops, let me try it again. Thank you very much for adding The Spaceport to the links.

Earth as Morning Star, one hour before sunrise from Gusev Crater, MER A Spirit.

As above but labled.

Phobos transiting the Sun, MER B Opportunity Sol 45.

Sol 709, Phobos in front of the Sun. MER B Opportunity.The irregular shape of Phobos is
clearly visible against the Sun. This is the only time as yet, that the entire profile of Phobos has been seen against the Sun. Worth mentioning, from Mars, the Sun on average appears only 20' across, where as from Earth it is approx 30' across & on average 44% as strong as from Earth.

Phobos & Deimos, both in front of Taurus the Bull. MER A Spirit. Familiar constellation, but from the surface of Mars, at times has two different moons.

Sol 696. Phobos seen here against the Hyades in Taurus the Bull by MER A Spirit. The bright star to the left of Phobos is Aldebaran / Alpha Tauri.

Phobos slipping into the shadow of Mars. Sol 675 MER A Spirit.

Phobos & Deimos, north of Sagittarius the Archer, MER A Spirit.

A predawn streak. Viking 2 orbiter or a Cepheid meteor.

1). Could be, the long silent Viking 2 Orbiter. This observation may well be that of the Viking 2 Orbiter catching the morning Sun, whilst close to Periareion. It issuggested that the 'object' moved four degrees in 15 seconds, a close match for the Viking 2 orbiter.

2). Another, possibly more likely explanation is the first ever meteor (shooting star) seen from the surface of the Red Planet.

This could have been part of a meteor shower whose parent body is Comet 114P/Wiseman-Skiff.

Because the radiant is in the constellation Cepheus, this meteor shower could be called the Martian "Cepheids", as the radiant for this suspected Martian Meteor Shower is in Cepheus. The timing is perfect, as this was at the peak of that suspected meteor shower & the direction of the streak, also points towards Cepheus, although of course the image does not reveal the direction of travel of the streak.

So any one's guess, 1 or 2?

A more detailed labled image of the above.

Morning Stars, Earth & Jupiter rise in predawn sky, Meridinai Planum, MER B Opportunity. Earth the brightest object rising in the centre, Jupiter appearing on the left. 

Jupiter on: Thursday 11th January 2007 MRO HiRISE. As viewed from Mars, Jupiter was at opposition & the MRO HiRISE obtained this remarkable image from Mars orbit.

Crescent Earth & Moon on: Wednesday 3rd October 2007, at a range of 142 million kilometers. Imaged by MRO HiRISE from Mars orbit.

Andrew Brown.

Enlarged image of a 250 metre wide patch of ground, near the centre of the Landing Ellipse.

A really fantastic primary mission.

I really hope that Phoenix makes it past the Martian northern Hemisphere Autumn Equinox, which falls on: Sunday 10th January 2009. After which, there should be the first signs of water & even CO2 frosts. Whether or not Phoenix makes that far is just pure speculation, but lets hope.

The primary mission is awesome. Hopefully the first successful landing in the polar region of another planet (though NEAR / Shoemaker did land near the south pole of Asteroid 433 Eros), hopefully get new insights into the Martian Arctic & history, not to mention, hopefully the first observations of the Martian Midnight Sun (I've already submitted a request of a movie of the Sun swooping low over the northern horizon @ midnight).

This mission is incredible & it annoys me when people moan, saying that it is only landing & digging holes, (landing on Mars is far from routine & is still a very special event) something we have already done with the Viking landers, but my arguement is that Phoenix's mission does not require roving & will still provide a complete new data set, from the surface of Mars in a very different location, to anywhere that we have been before (so far no two landing sites have been alike, all have been different).

Andrew Brown.

Hi everyone. I am Andrew Brown & some of you may know me from SDC, BAUT & The Spaceport.

Andrew Brown.