Secular and seasonal variations on Mars from integrated mapping based on photographic data and visual observatio

De Mottoni, G.

English

NASA Technical Reports Server

General Disclaimer 
One or more of the Following Statements may affect this Document 
 
 This document has been reproduced from the best copy furnished by the 
organizational source. It is being released in the interest of making available as 
much information as possible. 
 
 This document may contain data, which exceeds the sheet parameters. It was 
furnished in this condition by the organizational source and is the best copy 
available. 
 
 This document may contain tone-on-tone or color graphs, charts and/or pictures, 
which have been reproduced in black and white. 
 
 This document is paginated as submitted by the original source. 
 
 Portions of this document are not fully legible due to the historical nature of some 
of the material. However, it is the best reproduction available from the original 
submission. 
 
 
 
 
 
 
 
Produced by the NASA Center for Aerospace Information (CASI) 
https://ntrs.nasa.gov/search.jsp?R=19690004141 2020-03-12T08:05:38+00:00Z
PERSPECTIVES OF AREOGRAPHY
BAS`D ON PHGcGGRAPHIC DOCU^IIENTS
AND ON VISUAL OBSERVATIONS
by
G, D` MOTTON-1
Estratto dagli ATTI del Corvegno della S.A.I.
Padova-Asiago 7-9 ottobre 1967
(Offprint from the Atti of the Italian Astronomical Society Convention
Padua-Asiago 7-9 October 1967)
N69-1347 3
n	 (TMRU)0
IAC(;LUS1L;.4 NU MCiE R)
IGObE)
r I NAf"E_ )
ICATEGOAy)
11iASA CH OR T'+1% uR AO NU •bER
Translated for
JET PROPULSION LA30RATORY
C C.
i `/(,4'
2
r g cc^^
cri^ .Jrans^afions — 19711 GALWAY AVENUE — GARDIrNA, CALIFORNIA 90247 — Telephone: (213) 321-0881l
e
•
PERSPECTIVES OF AREOGRAPHY
BASED ON PHOTOGRAPHIC DOCUMENTS
AND ON VISUAL OBSERVATIONS
b r.,
G. DF MOTTONI
(Offprint from the Atti of the Italian Astronomical Society Convention
Padua-Asiago 7-9 October 1967)
GCNE'RAL INFORMATION
On the occasion of the work of cartographic synthesis' based on inter-
national photographic documents at the Centre de documentation sur Zes 	 .
pZanetes [Planetary Documentation Center] at Meudon organized by the
U.A.I. and within the framework of collaboration between the Milan and
Paris observatories, we have had the opportunity of examining at length
• wide range of documentation of great areographic interest, covering
• period of several decades and having thousands of photographs.
On the basis of the synthetic [compiled] ;naps previously made, we have
recently been ably to start a comparison for the purpose of locating
not only :,ea-onaZ variations, but also eeeular variations that have
taken place on Mars during two defined periods of time (see Figures _Z,
2, Z).
r
i
Figure 1
'Cf. Cartografi-a deZ pianeta Harte basata su documentazione fotografica
internazionale, a partire daZ 1907 [Cartography of the planet Mars based
on international photographic documentation starting from 19071. Publi-
ke1111 'lra#ij IiI it) n.j 19711 GAI WAY AVENUE - GARDENA, CALIFORNIA 90247 - Telephone. (213) 321-0881
i— From 1907 to 1920 during seven successive oppositions showing the
planet pass through all possible seasonal conditions.
From the three oppositions of 1907-1909-1911 to the three oppositions
of 1954-1956-1958, separated by a span of 47 earth years (correspond-
ing to 25 Martian years), but whose oppositions were respectively
[two by two] under identical seasonal conditions.
The first of these comparisons makes it possible to bring out in evidence
mainly "seasonal" variations, while the second shows variations essentially
of the "secular" type.
Naturally, to assure that the two types of phenomena could be clearly
distinguished, it would have been necessary that no other disturbing
cause of a recurring type occur in the climate of the planet even in an
irregular fashion.
i4ow, at least one such cause can be discerned; this is solar action at
the distance of the planet which, as is known, is an alternating recur-
rence even if it is not a true and proper regular periodicity.
While this action has varied within usual. limits, between 2 and 3 con-
ventional units, 2 during the 13 years of the first period of comparison,
this factor, no doubt relevant for Martian atmospheric phenomena, has
instead shown abnoriTial behavior by reaching quite exceptional values in
the month of August 1956, to be exact, around the 20th of the month.
ii
1
^t
I
	
i
i
Figure 2.
cation of the Milano-Merate Astr. Observatory, No. 17 and 18 NS
2 Cf . Attivita solare e fenomeni atm,osferici ou Nlarte neZ 1956 [Solar
activity and atmospheric phenomena on Mars in 19S6] Rend.; Acc. Naz.
Lincei, Vol. XLII, fasc. 4 (1967) .
^^e.i'^l`' Jrun^lafion+ - 19711 GALWAY AVENUE - GARDENA, CALIFORNIA 90247 - Telephone: (213) 321-0881
1)
i
a
i
j	 ^	 r
b•^y` ^	 f	 i
Fi gure 3
	
-^...
During those days, highs of 91 units were reached, not previously
reached since 1877, that is since Schiaparelli began with his systematic
and brillant observations, modern Areography.
Now, a very singular case has been verified which could hardly have
been due to a coincidence that just during those days of August there
occurred a combination of atmospheric -turbulence on Mars of a depth and
extent that were exceptionally great, so much as to be able to alter_
the appearance of very vast regions in a manner never before observed.
From these facts it must be concluded that even those phenomena which
initially seem to be of a "secular" type, as was the case in 1956, may
in reality be subject to some recurrence, even if it is not a true and
real regular periodicity, along with phenomena which may be called im-
pressive but destined to be rapidly exhausted and, therefore, with a
character quite different from true and effective "secular" variations.
SEASONAL VARIATIONS
With the above premise, we now come to the first type of changes that
could be noted by comparing the appearances of the Martian surface in
the period from 1907 to 1920. To be noted is the fact that our map,
are all based on photographs in red or yellow light which do not shown
phenomena located in the medium or in the upper atmosphere, but rattler
what takes place on the ground [surface] or the phenomena of "lifting
of desert dust to a low altitude caused by the aerial currents which,
however, are not very frequent.
Now, in order not to dwell on phenomena that are generall y known, we
shall confine ourselves to reporting on one aspect [appearance] that,
is definitely unusual, shown by the northern point of the Mare Sirenum,
the Titanum Sinus, which is one of the characteristic points of the
P9ar-t:ian surface, mainly because it retains its triangular shape and
its sharp point has been quite dark now for a long time.
In 1907 as well as in 1954, at the start of the local spring, this point
appeared almost all faded out, as though it were truncated at the
height of the 25th parallel (see Figure 4). At that point in the seasons,
the zone was going through the beginning of spring, not yet restored by
the aerial currents bearing the moisture "liberated by the melting of the
souther
/
n
//
 snows, currents which were still very distant toward the south
^i	 /eill'e^ 'I nilations - 19711 GALWAY AVENUE - GARDENA, CALIFORNIA 90247 - Telephone' (213) 321-0881
3
c
1
at that time of year. On the other hand, the sun was already relatively
warm and it was rediating at least 90 per cent of its maximum heat flux,
being close to its minimum distance from the planet.
The region of Sirenum and, particularly its advanced point in the heart
of the adjacent deserts of Memnonia and Zephyria must have been in a
climate of maximum dryness. This condition may, in our opinion, be
related to the abnormal appearance described above, which we do not
think has been previously observed.
Only once do we find an analogous variation, but quite different; this
is where Schiaparelli noted in 1.890 that the interior of the Sirenum
appeared noticeably clearer [lighter] even though the perimeter and the
northern point remained dark. It should be noted that then the region
was also in spring which began a few days before.
'b verify the above described hypothesis, it will be interesting to repeat
the observation of the region when the same seasonal conditions again
occur; this will take place in July 1969.
	
1
SECULAR VARIATIONS
Coming now to the second comparison, we shall briefly cite among the
appearances of the Martian surface after 47 years the principal modifi-
cations that have developed slowly, documented by our maps that com-
bine [synthesize] several hundreds of photographic documents.
1) "-Tani Fretum." This is a large dark bridge that has been connecting
the head of Sinus Sabaeus (Meridiani Sinus) with Margaritifer Sinus since
1864, joining them into a single blackish mass. Still evident in the
maps of 1907, 1909, and 1911, this dark band is completely absent on
those of 1954,. 1956, and 1958, while from the western head of Sinus
Meridiani we note an elongated shadow which extends towards Oxia Palus
but without reaching it; this shadow is visible even now
2) "NiZosyrtis." This is a large dark rope that in the past century
constituted the main artery of the planet. This "canal" [channel], al-
ready faded at the beginning of this century, appears in 1907 (see
Figure 5) subdivided into two parallel bands, by now very faint and
broken. In 1909 it is reduced to a single band, very pale, while it
reappears brit with less contrast and obviously because it is affected
by the influence of the season which, e.g., in 1914 obscured [cancelled]
its northern extremity.
After 47 years, in 1954, we find it reduced to a thin and pale thread
without any obviousness and almost total 1 v faded at the north [end] and
it remains like this in the two subsequent oppositions with a minimum of
variation. Even today this vestige of a great past is barely visible,
and it often shows a strange duality [duplicity] as in the oppositions
of 1946 and 1948 when it was observed at Pic-du-Midi to have split into
two thin curved lines, approximately 5 1 from one another.
3) "CrycZopia. " This is a great "lake" over 1000 km long and 600 kin wide,
which grew [developed] under our own eyes in the desert area of Aethiopis
parallel to the northern edge of Mare Cimmerium, occupying a region that
several times had shown considerable changes in tonality.
leeillc^ -Jranilationj - 19711 GALWAY AVENUE - CARDENA, CALiFORN1A 90247 - Telephone: (213) 321-0881
4
---
A
. ,.^-R•w. ,... ^.....t,.n..^++.^+s+•r ...-T •^:^w^rar,-.maq",s.T'7 rTaa+;^!^^•+.;•^"F;' T^'r'-',.^'^ "i^"r .
1	 r{:. 
-.Si
is 
Ili
j1	 r1 n 2 9..... ,..,.r 	 . v,- ^^........- - .' !^.3•'+' ^'+ ..-^.per.-.^ ►- a - ^- -" r•.!R...	 1	 / . .
r "
t	 t
^t
1907-195?
Figure 4
Until 1907 the edge of that "mare" had been fixed on the -10 0
 parallel
between the 220 0 and 240 0
 meridians as Schiaparelli had always drawn it.
Later one the edge started to move longitudinally until it reached and
passed the equator, but always without any lateral movement toward the
desert. However, in subsequent oppositions, those of 1909 and 1911,
a partial darkening of the tone in the region is already seen, with
alternating phases until 1920. However, photographic documents of that
period were not eery numerous due to the war.
Peiltly -.1 nilationj — 19711 GALWAY AVENUE -- GARDENA, CALIFORNIA 90247 — Telephone: (213) 321-0381
5
^.. ._ ^/rr —.r.a .^..	 yl--.r^. - -
	
r.Li^r^ 	 ^-.warm.._.	 ^r^.^.^+^J►+-
	
r	 `
t
t
1907
	
1909
i
{	 1914
i
'sue
l9f1
r
^	 s
i
t	 ;	 1
f	 -
`	 i
t
Figure 5
In the time span from 1920 to 1954, the photographs taken at Flagstaff
by Slpher help insofar as they show even in 1922 the great new dart:
spot (the "Sinus Gomer" of the Japanese) clearly discerned. This will
always remain visible from then on even if with noticeable variations
in shape and tone, evidently being composed of an enormous agglomeration
of minute formations subject to individual variations and may also be
related to climactic factors.
On our maps of the 1954-1958 period, the great lake of "Cyclopia" is
easily defined and its shows the tendency to extend slowly towards the
NW in the directio„ of Nepenthes, but without actually reaching it with
more than a tenuous tentacle, easily visible on the photographs of 1956.
This phenomenon of slow transformation of a "sub-desert" region into
• "lagoonal or lagoon-like" zone (to use the water analogy) has evidently
• secular character, but it nevertheless shows an evident seasonal
relationship too. In fact, Sinus Gomer has shown itself to be very
dark at perihelion, paler and sometimes invisible near aphelion. There-
fore, it appears clear that the intensity of its color increases during
periods of strong solar radiation. Vice versa, it does not appear
that the hygrometric factor has a significant effect on this phenomenon,
judging from the appearance of this object in the years 1922, 1924, 1939,
and 1954 when its very dark tone occurred without the wave of southern
`^ ^•`,,,	 er 
v	
an y ation^ -- 19711 GALWAY AVENUE - GARDENA, CALIFORNIA 90247 - Telephone: (213) 321-0881
6
_	 -	 y
darkening having yet reached the region. Inversely, the tone weakened
noticeably several times in periods during whirh the wave, coming from
the northern regions, reached and passed the zone in question.
we may therefore conclude that the dark tone of this formation (totally
non-existent before 1922) is excited more by the solar action than by
the moisture content in the atmosphere. At the next perihelion opposition
in 1971, it will be interesting to learn whether this interpretation will
be confirmed.
4) "Moeris Lacus-Nepenthes-Thoth-Casius"
we end this brief review with a few words about the great dark arc which,
starting from the eastern edge of Syrtis Major, reaches the ancient
Cope Palus (see Figure 5) .
In the 1907 photograph of this gigantic formation, visible today even
with the most modest instrument, only a rudiment existed at the southern
extremity of the arc, where Moeris Lacus was forming at the junction
with Syrtis. In the next representation, the eastern part of this
"lake" was already formed, while another year later, in 1911, Nepenthes
was born and so on until the entire impressive arc appeared in 1918.
In 1920 the middle part, between the +15 0 and +30° parallels, doubles,
splitting into two parallel lines having a distance of 5 1 between them.
These lines remained visible in practice for several years,often also
doubling part of Moeris Lacus and Thoth, even Casius.
This situation as well as a certain variability in the distribution of
the darkness maxima in single features [traces) of the arc is obviously
reflected in the maps of 1954-1958.
FUTURE PERSPECTIVES
Disregarding many other modifications of minor consequence although they
show some interesting aspects that we do not think should be enumerated
here, we shall pass now to a word regarding the perspectives that are
opened to modern descriptive Areograpry by the systematic study of
photographic documentation.
Although it is just the beginning, our work of graphic synthesis already
makes it possible to see the lines which, in our opinion, will be worth
following to give this branch of Planetary Astronomy a development
[growth) and efficiency commensurate with the interest it now sparks.
We are well aware, for in,tance, that while photography makes it possible
to fix the total appearance cf the Martian surface in relation to time
with satisfactory precision, it shows a rather modest degree of resolution
which even under the mc,^s t favorable conditions does not appear adequate
to allow the systematic study of the more minute formations, which are
instead accessible to visual observations.
Well aware of this, in this same publication  since 1959 we have expounded
3 Cf. Nuove carte del pianeta Marte sulla base dell fotographi del Pic- dit -Midi
[New maps of the planet Mars on the basis of photographs of Pic-du-Midi]
Atti convention of Venice-Naples S.A.I. September 19SS-September 1957.
lCeilly Jrani[ationj -- 19711 GALWAY AVENUE - GARDENA, CALIFORNIA 90247 - Telephune: (213) 321-0831
7
I
the results of a first attempt to "integrate" a photographic map by
inserting the most minute details supplied by visual observation. This
was done in the case of the 1948 opposition and with drawings mady by
Dr. A. Dollfus with the 600-mm refractor of the Pic-du-Midi Observatory
in the Pyrenees.
The experiment was successful and other "integrated maps" of this type
have been and are now being constructed at the request of the Meudon
Planetary Studies Center [Centro Studi Planetari di Meudon] like the
one almost completed relating to the appearance of 1946 (see Figure 6).
The examination of these maps rich in a surprising amount of minute
details and in delicate shades of tone, makes us think that this is
undoubtedly the best way to resolve the problem of descriptive Areography.
^ f this seems the best solution, we are nevertheless still far from the
goal, because photographic documentation still suffers from some improvi-
sation and is lacking in uniformity and continuity. This is because it
is being done at too small a number of stations and not all of them
suitably located and equipped, especially as far as their distribution
in the two hemisphere is concerned.
Moreover, visual observations are furnished by too small a number of
observers who do not always operate under the best conditions, especially
for the perihelion oppositions which should be followed by stations
located in the southern hemisphere.
Naturally, in indicating these perspectives of areographic development
by means of a rational use of the photographic method as well as by
visually performed study, we cannot forget that just recently another
powerful investigative method has joined those considered traditional:
direct automatic astronautic exploration of the bodies of the solar
system. This has already yielded a first, very interesting result
with the memorable feat of -the American probe "Mariner IV" the first
results of which we have had the opportunity of studying in detail.``
in this way it will no doubt be possible, shortly, to obtain information
absolutely unattainable with the telescope; however, the systematic
study of Mars will for a long time remain still confined to the tele-
scope, at least for the part that requires continuity of observations.
Naturally, the search for the most favorable conditions for observation
will lead, perhaps soon, to the organization of telescopic stations
placed outside the earth's atmosphere, either in orbit or on the sur-
face of the moon. These stations will make it possible to exploit the
optical qualities of large instruments in full which are seriously
impaired on earth by the insurmountable obstacle of our atmosphere.
4 Cf. Sulle fotografie di Marte ottenute dalla sonda automatica "Mariner ,Ivrf
[On the photographs of Mars obtained by the automatic probe "Mariner IV"]
Publication of the Milano-Merate Astr. Observatory, No. 15 NS
^ llt 5 ^ fLei	 raps u ions — 19711 GALWAY AVENUE — GARDENA. CALIFORNIA 90247 — Telephone. (213) 321-0381
8
Integrated maps
rte, _ ..	 ....-r,. ^ .,.^.—v..,.: ,•,.,..^s-7- .. 	 -	 . rs.-	 ^ ^r,.,yt•r....c :.	 -
1j
'	 -.	
^ '^ ^^`"',^'"y~r ^' ^ 
.,fir 
•° ^ '" ^`'^^` •"
t
Figure 6
1
Kehl`' J^an^lafion^ - 19711 GALWAY AVENUE - GARDENA, CALIFORNIA 90247 - Telephone: (213) 321-0881
9


Perspectives of areography based on photographic documents and on visual observations

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server